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RHR: Surprising New Vitamin D Research, the Myth of Multi-Tasking, and How the Internet Is Rewiring Our Brains


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In this episode I review new research on vitamin D that has led me to slightly modify my recommendations, and we discuss how multitasking and the internet are literally rewiring our brains.

It’s also the first episode with our super-duper new sound dampening equipment. I think we’ve finally reached audio quality nirvana. Let us know what you think!

In this episode, we cover:

3:16 A surprising update on new vitamin D research (and Chris’s revised recommendation)
26:53 The myth of multitasking – and what you really need to know
36:39 How the internet is rewiring our brains

Links We Discuss

Full Text Transcript:

Steve Wright:  Hi, everyone.  Welcome to another episode of the Revolution Health Radio Show.  This show is brought to you by ChrisKresser.com, and I’m your host, Steve Wright from SCDLifestyle.com.  With me is integrative medical practitioner and healthy skeptic Chris Kresser.  Chris, how has your day been going?

Chris Kresser:  It’s fantastic.  It’s so beautiful lately here.  It’s been in the high 70s and 80s.  I’ve been outside every day getting some sunlight and vitamin D, which actually we’re going to talk about today, and doing lots of hiking with Sylvie and Elanne.  It’s one of these times where I’m just so grateful to live in California and particularly this part of California where I live, so couldn’t be better.  How about you, Steve?

Steve Wright:  Well, you’re making me a little jealous, but I am riding an avocado high right now.  I just had this massive avocado, so I have a belly full of fat, and I’m interested to hear about this new vitamin D stuff because I’ve actually been doing my own tinkering.  I cut off all vitamin D supplementation in February and just ran my numbers, and I’m back down to 30 without anything except for one or two teaspoons of fermented cod liver oil a week.  So I’m curious to see what the new stuff is, and I think it’s going to be a good show.

Chris Kresser:  Yeah, we’ll get into it.  My other update is that I’m not in the closet again, but I have this fancy new audio-dampening equipment.  There are these two heavy screens with some kind of material; I’m not even sure what it is.  There are two screens, and each of them has two panels, and then they have hinges so you can kind of position them any way you want.  And so I’m sitting in a chair, and I’m basically wrapped around by these panels, and I think it’s going to make a big difference, but we’ll have to hear from all of you to tell us if it does or not.

Steve Wright:  Yeah.  Leave a comment.  If you’re in iTunes, go over to ChrisKresser.com and let us know about the sound quality.  So, Chris, before we get into this week’s show, go ahead and fidget with your new sweet screens, maybe reach outside of them and get a drink of water, and I want to tell everybody about Beyond Paleo.  So if you’re new to this podcast, or if you’re new to the paleo diet, or maybe you’re just interested in optimizing your health, you’re going to want to check out what over 30,000 other people have already signed up for.  It’s Chris’ free 13-part email series called Beyond Paleo.  Now, this email series goes over Chris’ best tips and tricks for burning fat, boosting energy, and preventing and reversing disease without drugs.  To sign up, go over to ChrisKresser.com, and look for the big red box.

OK, Chris, did you get in and out of your box?

Chris Kresser:  I’m in my cocoon.

Steve Wright:  OK.

Chris Kresser:  It’s amazing.  It totally blocks out the sound even from my own office.

A Surprising Update on New Vitamin D Research (And Chris’s Revised Recommendation)

So I want to talk about a couple different things today, and we’re going to start with vitamin D.  There’s a lot of new research coming out that is pretty surprising, I think, to many of us who’ve been following this issue for a while, perhaps more surprising to people who’ve been recommending really high levels of vitamin D.  For the last several years I’ve been warning against excessively high levels of vitamin D for some of the reasons we’re going to talk about today, but there’s a lot of controversy about this.  The science is definitely mixed and inconsistent, and the jury is certainly not out.  But I want to talk about some of the newer findings and go into some detail about what that might mean in terms of optimal vitamin D levels and vitamin D supplementation and sunlight versus supplements and things like that.  And then if we have time, I want to talk about multitasking, electronic media, and how the Internet is rewiring our brains.  It’s a topic that I’m really fascinated by, and I heard an interview with a neurologist on NPR Science Friday last week about it that really just kind of got my juices flowing about it again, and so I gathered together some of the research that I’ve done on this over the years, and I’ve been doing additional research about it for my book, which is coming up soon.  I’ll have an exciting announcement about that, I think, probably by the next show.  So consider this a preannouncement.

Steve Wright:  Dun dun duunnn.

Chris Kresser:  So let’s get into it, and we’ll see how far we get, and we can pick it up on the next show if we run out of time.

The stimulus for this vitamin D conversation, the most recent one at least, was a new prospective cohort study with over 1.2 million participants, so a pretty big sample size.  And this study showed that the lowest mortality or risk of death from all different causes and the lowest rates of cardiovascular disease were observed at vitamin 25D levels between 20 ng/mL and 36 ng/mL.  That may surprise some of you because as you probably know, in the US the lower end of the lab reference range is 30 ng/mL, so a big chunk of that range where the researchers found that the risk of death and heart disease was the lowest is actually in a range that would be considered deficient by current standards.  This isn’t the only study that reached this conclusion.  There are actually several other fairly large epidemiological studies that have been done in the past few years that have suggested that the optimal vitamin D level might be much lower than is currently recommended, especially by some of the vitamin D advocacy organizations, like the Vitamin D Council.  Some of the other studies, the range was 20 to 30.  I think there was one that was 20 to 35, and then one went up to, I think, as high as 40, so it’s all basically in the same range.

Now, as I’m sure many of know who have been listening to this show now for a while or have been following my blog, you understand that observational research, epidemiological data like this always has to be taken with a big grain of salt because there’s a lot of potential for confounding factors.  You know, something that we might consider right off the top of our head is that vitamin A and vitamin K2, as Chris Masterjohn has pointed out in several really great articles on his blog and in the Weston A. Price journal and that I’ve written about as well, vitamin A and K2 protect against vitamin D toxicity.  So one reason that people with higher vitamin D levels in these studies might be experiencing a higher risk of death and a higher chance of cardiovascular disease is that they’re also deficient in vitamin A and vitamin K2, which would lower the threshold for vitamin D toxicity.  And unfortunately, we have no way of knowing whether that’s the case because in these big studies of vitamin D levels, they never measure vitamin A or vitamin K2 status.  And there’s even controversy about how to accurately do that, so I don’t think that’s, unfortunately, going to happen anytime soon.  We’re left to just kind of speculate based on the biochemical mechanisms that we understand and some other studies that have shown that vitamin A protects against vitamin D toxicity and vice versa.

And then just understanding the mechanism of K2, one of the main roles of K2 is to make sure that calcium gets into the bones and the teeth and the hard tissues where it belongs and stays out of the soft tissues where it doesn’t belong.  And vitamin D, of course, regulates calcium metabolism, too.  So if you have really high levels of vitamin D, which could increase soft tissue calcification, and then you have low levels of vitamin K2, which would also contribute to soft tissue calcification, that’s kind of a double whammy.  And a lot of people probably do have vitamin K2 deficiency.  Vitamin K is plentiful in green vegetables and can be converted into vitamin K2, but the conversion is pretty inefficient.  And vitamin K2 is only found in certain foods, like organ meats and natto, which is a fermented soy product, and cheeses, particularly grass-fed dairy and grass-fed cheese because, as I just mentioned, vitamin K is found in green vegetables or in grass that the cows eat.

So with all those caveats in mind, let’s just talk a little bit about some of the problems with the idea that a vitamin D level of 50 or above, which I think the target for the Vitamin D Council is 50, and their suggested range is 40 ng/mL to 80 ng/mL with a target of 50, but when you look at the actual research that was done to determine the reference range for vitamin D, you’ll find that it’s pretty thin and sloppy in a lot of cases.  The earlier justification for the reference range of 30 and above, which is the one we use in the US, was looking at what level of vitamin D led to the maximum suppression of parathyroid hormone, and this was based on looking at parathyroid hormone levels in cross-sectional analysis of large populations, and there is a point where the average parathyroid hormone level bottoms out, but the range is really enormous.  There’s tons of variation in these studies.  So it’s really difficult to say this level of vitamin D is optimal for suppressing parathyroid hormone in everybody because the variation was so big.  And then the Vitamin D Council, I think, based their recommendation of 50 ng/mL on a similar type of evidence, but in this case, as Chris Masterjohn pointed out to me in a discussion we were having about this, the endpoint was the inferred storage of vitamin D in body fat and then saturation of an enzyme called 25-hydroxylase, I think that’s involved in converting 25D to the active form of vitamin D, which is 1,25D.  So there were never any obvious connections to serum vitamin D levels and any clinically significant endpoint in the Vitamin D Council’s recommendation.  And then they took two of the older studies on this issue and used one of the studies that later was found to have unreliable methods of reporting 25D levels.  I know that’s probably pretty technical and complicated, but the gist of it all is that the studies that were used to determine these ranges, 30 and above and then 50 ng/mL for the Vitamin D Council, are problematic and have been criticized by a number of different commentators in the scientific literature.

Steve Wright:  Hey, Chris, you mentioned 1,25D as well as 25D.  Which one’s the active form, and do we know much about the ratio between the two?

Chris Kresser:  Yeah.  The inactive form is 25D, and that is converted into 1,25D, which is the active form.  A lot of the effects of vitamin D toxicity that we’re talking about now happen when there’s too much of the active form in the body.  Something else that’s pretty interesting about that is that there are variations in how much of the active form, 1,25D, will be produced from a given amount of 25D, the inactive form.  And there are actually genetic polymorphisms that have been identified at this point that vary geographically that affect that conversion.  For example, we know that among Indians the level of vitamin 25D that’s required to produce a given level of 1,25D is higher than among the Inuit.  That suggests that the optimal vitamin D exposure for Indians in Southeast Asia, those living in equatorial regions, is higher than for people living at northern latitudes.  And this is a fairly new finding, but it really means that one person’s optimal vitamin D level is different than another person’s, and unfortunately we’re not at the point where we can easily identify that and where you can go in and just get a test and get a piece of paper that says this is your optimal vitamin D based on your genetics and skin color and latitude and all of that stuff.  It probably isn’t that far away, but we’re not there yet.

Steve Wright:  Why is all the research done on the inactive form, though, and not on the active form?

Chris Kresser:  Well, that’s a very good question.  Actually in this conversation I was having with Chris Masterjohn, one of the things that he brought up is that 25D has been long used as the main marker for vitamin D status, and it’s been assumed that it’s an accurate marker of active vitamin D status, but it turns out it’s possible to have kind of a disconnect between your 25D levels and your 1,25D levels.  They’re not always what you would expect them to be, in part because of these polymorphisms and in part possibly because of disease states that cause an over-conversion of 25D to 1,25D, the active form, that happens in some autoimmune diseases.  So 25D turns out to not be a very good indicator of vitamin D status, and I believe Chris said he’s going to be writing a blog series about this in the future, which I look forward to reading, and he’s going to take on that topic specifically.

The other thing about this, too, that makes me think that the optimal level might not be as high as we thought is that in most indigenous populations that have been studies, their levels of 25D are typically lower than 50 ng/mL.  I think the highest level in any indigenous population that has been measured was 46, and that was in the Maasai.  But as Chris pointed out, that was done with modern Maasai who no longer paint themselves for war and are living a different lifestyle than their predecessors would have been, so we can’t really know necessarily that that historically would have been the typical vitamin D level in the Maasai population.  But even if it is, that’s still the highest that’s ever been identified in any traditional population.  Usually it’s significantly lower, and that’s still lower than the 50 ng/mL recommendation from the Vitamin D Council.

So when all of this is taken together, it does make me wonder what the optimal level for vitamin D is as a general recommendation, given that we can’t really identify all the individual differences yet.  Up until today I’ve been recommending a range of 35 to 50 or 60 and ensuring that vitamin A and vitamin K2 levels are adequate, and I don’t think that that’s far off, even considering everything that we’ve been talking about today.  I’m thinking about lowering the lower end of that to maybe 30 or 25, targeting 35 ng/mL as a kind of optimal number with an upper limit of maybe 50, and I think that range of 25 to 50 is pretty well supported by the current evidence, and I don’t think there’s much of a risk of toxicity at 50 if you’re getting enough vitamin A and vitamin K2.  And considering that bone density peaks usually between 20 ng/mL and something like 35 in people over 50 — in some populations it continues to increase up to 45, like in Mexican-Americans, I think — I think that’s probably a pretty good range to shoot for, 25 to 50 with a target of 35.

Steve Wright:  So is there also a target range or a number that people should start tracking for the active form, the 1,25D?  You know, for a long time, the push was always to only get the inactive form tested.  Now with all this new research, those of us who are testing freaks and just like to monitor this stuff on a regular basis, is it worthwhile to start getting the active form tested, too?

Chris Kresser:  It may be, but I don’t know enough about it yet to make a recommendation.  I mean, there’s far less literature on that topic just because 25D has been the recognized marker for vitamin D status for so long, so that’s what’s usually used.  Some studies do measure 1,25D along with 25D, but a lot don’t.  So there’s just less data to draw any conclusions from.  The data on 25D on already so unclear, so it’s going to take some time for me to dig into that a little further, but of course, as always, I’ll keep everyone posted.

There are a couple other things to point out about this.  Generally, sunlight is considered to be a safer way of meeting your vitamin D needs if you can.  I mean, obviously that’s not possible for everybody, depending on where you live and your lifestyle, etc., and your skin tone, because full exposure to sunlight, midday sun exposure 15 to 20 minutes in a light-skinned person produces about 10,000 IU of vitamin D, but in a darker-skinned person, it could take up to 2 hours to produce that same amount of vitamin D.  But one reason why sunlight might be better than supplements is that the body does have some ability to put the breaks on the conversion of ultraviolet light into vitamin D when it’s had enough.  So there’s a little bit more of an inherent regulatory mechanism there, whereas when you eat vitamin D in the form of supplements of foods, although there aren’t many foods that have much vitamin D, there isn’t really a regulatory mechanism there.  You’ll just keep absorbing more and more vitamin D from the gut even when you have more than you need.

The other reason is that sunlight has been shown to have several other benefits aside from vitamin D production.  You don’t need a degree in science to know this!  People feel good when they go outside and they get sun.  But it is interesting to see some of the research.  For example, sunlight has been shown to increase nitric oxide production, and nitric oxide is a vasodilator, and that means it will lower blood pressure.  And blood pressure is one of the single strongest independent risk factors for heart disease.  In fact, I think I remember seeing a study that a drop in 20 mm Hg of systolic blood pressure — which is the number on the top of the equation.  When they say 120/80, the 120 refers to systolic. — A drop in only 20 mm Hg cuts heart disease in half in people who are 20 to 49 years of age, so it’s a really, really significant risk factor, and anything that lowers blood pressure will have a really big impact on heart disease risk.  And sunlight increases the amounts of nitric oxide, which in turn lowers blood pressure.

There are also a lot of other studies that suggest that the incidence of autoimmune diseases is correlated with sunlight and ultraviolet light exposure.  It’s been observed for some time that MS flares happen more in the winter than they do in the summer.  People are more likely to have MS that are born in northern latitudes without much sun exposure and less likely to have it in equatorial regions.  And of course, you could say:  Oh, well, we don’t know where the chain of causality lies there.  But interestingly enough, when people move from one place to another, they assume the risk of the new place, so that suggests that there is a causal relationship and it’s not just something to do with the genetics of people living at those different latitudes.  That said, it is still possible to experience vitamin D toxicity from only sun exposure.  There was a study done on Israeli lifeguards, and their vitamin D levels were between 50 and 60 ng/mL just from sun exposure.  They weren’t supplementing at all.  And their rate of kidney stones was 20-fold higher than that of the general population, which is a pretty significant difference, and that’s probably caused by an increase of calcium.

There’s definitely a lot more to this story than is typically reported in the media.  There’s no doubt that vitamin D is crucial.  It affects over 3000 genes.  It plays a really important role in a lot of different processes.  Vitamin D deficiency is associated with numerous different diseases, so yes, we absolutely need to ensure adequate levels of vitamin D.  But as is the case with many other nutrients, perhaps all nutrients, there is a U-shaped curve for vitamin D, which means too little of it is not good, but too much of it is also not good.  And I think now we’re starting to see more research on the other end of that spectrum, whereas for a while it was almost exclusively dedicated towards the effects of deficiency.

Steve Wright:  You know, just more anecdotal ideas, but interestingly enough, last week I asked on our SCDLifestyle Facebook page how many people have flare-ups of their digestive issues in the summertime, and the overwhelming feedback was that people always seem to be healthier in the summertime.  And I think you hit on a great point there, Chris, that science doesn’t even understand how beneficial the sun is, but it seems like from every possible angle being out in the sun and getting adequate exposure on a daily basis seems to really help everyone.

Chris Kresser:  Well, yeah, and this is once again where the evolutionary lens can be helpful.  I mean, we evolved in an environment with a lot of sunlight, in the equatorial region, and it makes sense that we would be genetically and biologically adapted to that kind of environment.  And yes, it’s true that genetic change didn’t stop in the Paleolithic, and a lot of genetic changes have occurred since that time, which we’ve discussed a lot on this show, but it doesn’t mean that our entire genetic makeup has changed.  And so we’re still kind of hardwired to have some sun exposure, and there’s definitely a lot of modern evidence that supports that as well.

OK, so we’ll come back to that.  Let us know what your questions are.  This is an ongoing investigation, and it’s something that I continually discuss with Chris Masterjohn, Stephan Guyenet, and Robb Wolf, and we have a kind of little email group.  We trade studies when they come out, and we talk about them, so I’ll be curious to see how the research evolves over the next few years.

Steve Wright:  Great, well, that’s like part 2 or 3 for you, so stay tuned until parts 4, 5, and 6.

Chris Kresser:  Exactly.  It’s a work in progress.

The Myth of Multitasking – and What You Really Need to Know

All right, so we may not have time to finish this.  We’ll probably come back to it, and it’ll probably be a multipart series because it’s an issue I’m really interested in and I think it’s important, and it’s one that I don’t think gets enough airplay, and there’s actually a lot of resistance to it, even among my audience, I’ve noticed, whenever I post something about it, which I’ll come back to in a minute.

So the other day I was driving the car and I was listening to a program on Science Friday, and Ira was interviewing a neuroscientist… I believe he’s a neuroscientist.  He’s a professor at Stanford, his name is Clifford Nass, and the topic was multitasking, or rather the myth of multitasking.  And that was Nass’ contention, that it is a myth, and of course, there’s a ton of other studies that back that up and that basically say that multitasking, at least in the case of computers and electronic media, is a misnomer and that we should really be calling it multi-switching because the human brain doesn’t have the capacity to focus on several tasks at once.  And if you are multitasking, what you’re doing is just switching really quickly back and forth between tasks.  He did a study of 262 college students to complete experiments that involve switching among tasks, number one; and then filtering irrelevant information, number two; and then using working memory.  Working memory is the part of our memory that we’re consciously aware of.  We have short-term memory, working memory, and long-term memory.  And working memory is the part that calls stuff out of long-term memory, and it’s what we’re kind of, like I said, consciously aware of at any given moment.

The researchers thought that effective multitaskers would outperform the people that were just focusing on single tasks, and they turned out to be completely wrong.  The multitaskers were terrible at all three of the tasks, and the scariest part was that only one experiment actually involved multitasking.   The others were just single activities, which of course suggests that frequent multitaskers use their brains less effectively, even when they’re focused on a single task.  And it also suggests that multitasking might actually rewire our brains in a way that isn’t beneficial.  Other research out of other labs has shown that when people focus on two tasks at the same time, each side of the brain tackles a different task, and that suggests that we might have a two-task limit.  So again, this idea that we can focus on four or five different things at once is really a myth.  But that doesn’t stop most of us from trying, right?!  Another study at Stanford, I think by Nass as well, found that 25% of students at Stanford use four or more media devices when they’re using one.  So if they’re watching TV, they might have their phone, their tablet, and perhaps a computer or something else going.  They’re writing a paper, they’re on Facebook, they’re tweeting, and they have music playing.  This, of course, is increasingly common.  It’s not just limited to students at Stanford.

And younger kids are increasingly using media and multitasking with media.  For a long time, the American Academy of Pediatrics has been recommending that kids under 2 years of age have no screen time at all.  And this is based on a large body of evidence showing that screen time for kids that young may have harmful effects, and yet, according to a Kaiser Foundation report, 90% of parents report that their kids under 2 years of age are using electronic media, 68% of kids under 2 years of age use electronic media for more than 2 hours, and 26% of kids under 2 have TVs in their room.  This is less true for kids under 2 who can’t probably turn on the TV themselves, but for older kids when TV is in the bedroom, viewing increases by 1 or 2 hours per day, and the risk of being overweight increases by 31%, and the likelihood of smoking doubles.

Steve Wright:  This is staggering.  Twenty-six percent of kids under 2 have a TV?!

Chris Kresser:  Yeah, and almost 70% are using electronic media more than 2 hours a day.  Getting a little older, the average American child now spends more than 7 hours a day in front of an electronic screen.  The only other activity that the average kid does more than planting himself or herself in front of a screen is sleeping, and that’s actually reducing.  We’ve talked before about the decline in average amount of sleep, so they’re probably getting closer.

Screen time in many ways also is replacing green time.  Recent studies have shown that people living in the US, Japan, and Spain are spending between 18% and 25% less time in wilderness or natural environments today than they were just 30 years ago.  This is, of course, a concern because nature has been shown to have numerous health benefits.  For example, in preschool children, time spent outdoors in nature is the single most predictive factor in how physically active they’ll be.  Other studies have shown that contact with nature reduces stress, reduces loneliness and depression, helps with stress tolerance, improves mood, etc.

Steve Wright:  Up-regulates the immune system.

Chris Kresser:  Yep, up-regulates the immune system.  And there are a lot of theories on why this might be.  One of them was created by E.O. Wilson, who coined the term ‘biophilia’ and the biophilia hypothesis.  This is basically a fancy way of saying that humans are inherently drawn to natural environments, and it’s based on a lot of studies that demonstrate how strongly people respond to open grassy landscapes, scattered stands of trees and meadows, water, winding trails, and elevated views, which is exactly the environment that humans evolved in.  The biophilia hypothesis is not universally accepted.  It’s somewhat controversial, but it certainly, to me, makes sense from an evolutionary perspective.

I recently came across, while researching for my book, a study by a couple of other researchers named Zaradic and Pergams, and they coined a new term, in kind of a play on biophilia, called ‘videophilia.’  And videophilia is the love of playing video games, surfing the Internet, and watching movies and TV.  And in contrast to biophilia, it’s been shown to have harmful impacts on our health.  It can increase the risk of obesity, contribute to a lack of socialization, possibly to attention disorders and poor academic performance.  The evidence on screen time and ADHD, for example, is somewhat controversial and mixed.  There are certain studies that suggest a connection between screen time and ADHD and others that don’t, and even in the ones that do suggest a connection, it’s not always clear where the causality lies.  But on the Science Friday program I was listening to, Clifford Nass made a good point, which was that ADHD is actually a misnomer.  It’s not a deficit of attention.  We all have the same amount of attention, essentially.  ADHD is problem where the attention that we have to devote to any particular thing is spread over too many things.  And if you think about it, that’s exactly what multitasking does, right?  It spreads our attention over an increasing number of things.  If you’re writing a paper and then you have Facebook and Twitter open and your email and your phone and music, that’s dividing your attention among multiple different inputs.  And it’s not at all hard to see how doing that kind of thing on a regular basis could lead to behavior that would be labeled as ADHD.  There are about seven studies documenting the possibility of language delays in kids that are exposed to excessive electronic media under 2 years of age, and there’s not a single study showing that electronic media contributes positively to infant development.  There’s a lot of research showing that unstructured play time in the real physical world is far more important to the development of creativity, problem solving, reasoning skills, and motor skills than electronic media.

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How the Internet Is Rewiring Our Brains

And the most disturbing thing, I think, about all of this is research that suggests that using electronic media, playing video games, computers, and the Internet is not only changing our behavior, but it’s actually rewiring our brains… and not in a good way.  I’m reading this book right now called The Shallows: What the Internet Is Doing to Our Brains.  Maybe some of you have read it or heard of it.  It’s by a Pulitzer Prize finalist, Nicholas Carr, and the whole subject of the book is how the Internet is actually physiologically changing our brain.  It’s been long thought up until, I don’t know, maybe the past few decades that the mainstream theory was that the brain was static and it didn’t really change much in our adult lives.  There were, as far back as the ’50s, I think, a few heretics that were challenging that idea and maybe even further back, but really the dominant paradigm was that once you’re born and you go through the main developmental period, once you’re an adult, your brain is just set, and you can change your behavior, but it’s not going to have any impact on any real physical connections in your brain.  But now there’s overwhelming evidence that that’s not true and that the brain is actually quite plastic.  This means that the way that we think and behave can form new connections and really literally rewire our brains.  There’s a saying in neurology that neurons that fire together, wire together.  And that just reinforces what I just said.  There’s a great quote in the book where Nicholas Carr says: “If, knowing what we know today about the brain’s plasticity, you were to set out to invent a medium that would rewire our mental circuits as quickly and thoroughly as possible, you would probably end up designing something that looks and works a lot like the Internet.”  What he means is that the online environment involves a certain kind of stimuli that is exactly what would be likely to rewire the brain.  The online environment “promotes cursory reading, hurried and distracted thinking, and superficial learning,” and a state of mind which the poet T.S. Eliot called “distracted from distraction by distraction.”

I just want to take a pause here for a second and give everyone a little bit of a breather and let you know that I’m not suggesting we don’t use the Internet.  I mean, you wouldn’t even be listening to me if it wasn’t for the Internet.  I wouldn’t have my blog.  I wouldn’t be able to do the work that I do.  Of course, the Internet is here to stay.  I’m not a Luddite in any way.  I am suggesting that some of these new technologies have consequences, and as much as we love them and use them and benefit from them, that we should at least be open to considering what the science says about the consequences and possibly adjusting our behavior based on that.

So getting back into this, there’s another neuroscientist named Michael Merzenich, and I think he’s at UC San Diego.  And he’s repeatedly warned that our brains are “massively remodeled” by exposure to technologies like the Internet.  He said: “When culture drives changes in the ways that we engage our brains, it creates different brains.”  And he goes on to say that the use of the Internet and other electronic media has significant “neurological consequences.”  He did a great study to illustrate this.  He took two groups of people, one that was really experienced with the web and using Google, and the other group was people who were complete novices and hadn’t used the web or Google much.  I don’t even know where he found these people!  It just seems so ubiquitous now.  So he scanned their brains as these two different groups used the Internet, and the people with experience using the Internet had much higher levels of activity in an area of the brain called the dorsolateral prefrontal cortex, and the people with very little experience or no experience using the Internet and Google had almost no activity in that brain region.  And as a control, he had both groups read just linear text from a book, and they had not identical, but very similar levels of brain activity.  So that suggests there wasn’t any fundamental difference in the brains of these people.

Steve Wright:  Well, I hope he age-matched them because I think the only people he could have found that were novices were probably a little bit older.

Chris Kresser:  Yeah.  So then the remarkable thing about this study was that he repeated the test six days later, but in the interim the researchers had the people who were previously novices spend about an hour a day online, you know, using ‘the Google machine,’ and when they measured again, the novices’ prefrontal cortex that had been largely dormant before now showed extensive activity at a level almost equivalent to the prefrontal cortex of the people that were experienced.  So, just 5 hours over 5 days of Internet use completely changed levels of activity in the brain.  And he asked the question, “If our brains are so sensitive to just an hour a day [for 5 days] of computer exposure, what happens when we spend more time [online]?”

The intro, the whole kind of premise of this book that I’m reading, The Shallows: What the Internet Is Doing to Our Brains, is that Nicholas Carr, who is a writer and a journalist, an author, and someone who has spent his life reading books and writing books, was noticing over time that he was less and less able to focus on a book, to actually read a book from start to finish, because as he increasingly used electronic media and online technologies, his attention became more and more fragmented.  He found it more and more difficult to focus on any one thing for any significant length of time without wanting to get up and go check his email or take a call that was coming in or check his Facebook feed or whatever.  And he went around and he interviewed a bunch of other people and found that he wasn’t alone, that a lot of people were reporting a similar kind of experience, and people had mixed feelings about it.  Some people felt like:  I don’t need to read books.  I can get everything I need.  All the books are indexed on Google.  If I want to look something up, I can just type it into a search engine and it’s right there.  The Internet has unquestionably vastly expanded the amount of information that’s available to us.  I mean, I couldn’t even imagine how I could do the work that I do without the Internet and PubMed.  The kind of research that I do to write a blog post would probably have taken weeks or monthly to do before.  I mean, it’s really profound, and it’s incredible, the benefits that have come from it.  But there’s another side to the coin, as it turns out, and I’ve certainly noticed it in my own life.  If I have a day where I’m spending a lot of time online or on a computer, my mind feels different.  I definitely have a different experience of thinking.  My body feels differently, too, although that’s a slightly different topic.

My point in bringing this up is that, like I said before, I’m not suggesting we stop using computers or stop spending time online.  That’s pretty ridiculous for most of us.  I am suggesting there may be consequences to this new technology, and the consequences that we’re beginning to understand are not necessarily all beneficial.  And the hardest part about this is that it’s a problem without a solution.  Not all problems do have solutions.  It’s not always so easy and black and white.  And maybe a better label to use for this would be a predicament, because with a predicament you can respond to it in any number of ways, and that doesn’t necessarily make it go away, but it’s just a way that we are in relationship with it.

Quite a while prior to reading this book, I kind of recognized this on my own, and I had also read some other studies.  And then actually, I think, a while back when Tim Ferriss released his first book, I read a review about it where he talked about batching email.  And so I started doing things, like I turned off all notifications on my phone, and even the ringer off and I don’t leave it on unless I am available to take calls.  But I’ve turned off any email notifications, so if an email comes in, it doesn’t beep or show a badge or anything like that on my phone.  I’ve turned that off for my email program.  I keep my email program off except for distinct periods throughout the day.  And this is actually recommended by Clifford Nass, the neuroscientist at Stanford.  He suggests when you use email that you do it in distinct periods of at least 20 minutes.  Most people just check email periodically through the day.  They leave their email open.  If they’re working on something and an email comes in, they feel obligated to kind of go over and get it.  And as an interesting kind of side note, part of that is because that is rewarding.  We’ve talked about the food reward concept with Stephan Guyenet and the concept of reward as a psychological term.  Something that is rewarding makes us want to do more of it.  Email and all these kinds of notifications of something popping up on your feed or a tweet, that’s all rewarding from a psychological perspective.  It satisfies something for us, and it makes us want more.  The vast majority of people will just leave their email open, and any time something comes in, they go over and they check it, and that ends up distracting them, it dilutes their focus, makes them less effective in whatever else it is that they’re doing.  Tim Ferriss recommended just checking email two or three times a day and leaving it closed the rest of the time.  Clifford Nass’ recommendation isn’t a specific number of times that you check email but that when you do it, you devote at least 20 minutes to it as an activity, and then when you’re finished, you stop and don’t come back to it again until you’re ready to devote another 20 minutes.

You know, if I’m writing my book, for example, I have everything else closed.  There’s no Facebook, there’s no Twitter, no email.  Even for me, I’ve never really liked having music on when I write or read.  I prefer just to focus on what I’m doing.  And I’m still a big fan of books.  I actually read a lot of books.  I read them from start to finish.  And I don’t know why that is, and there’s no better or worse, it’s just that I’ve always been a book lover, and for whatever reason, that hasn’t stopped even in spite of how much I use computers and electronic media.

So I think there are little, small things that can be done like I just mentioned that can significantly mitigate the potentially harmful consequences of all this stuff.  And I think the added benefit there is that there aren’t that many opportunities for solitude anymore in our culture.  It used to be that if you were walking or maybe you were taking public transportation or riding a bike or you were in a car, there were moments where you just naturally had the opportunity to be alone with yourself and your thoughts, and I think that that’s really important for psychological and emotional and spiritual health and actually for creativity and deep thinking and just being a healthy person in this world.  But these days, the opportunities for that seem fewer and fewer if we have phones with us at all times, and I regularly see people checking their email and stuff walking down the street.  I’ve done that a few times myself, so I’m not perfect!  You know, we have access to all kinds of different programming in the car now.  If we’re on the BART, we have an iPad with us or a phone.  It just seems like there’s a lot less time now for those spontaneous moments of solitude and quietness and just being in our own little world, and I just wonder about the effects of that.  I think this is an unprecedented time.  There’s never been a time in human history where we’ve had that kind of disconnection from self and as much exposure to this kind of stuff as we have now.  And my idea is that it’s having a significant effect, and I think there’s a lot of research to support that, but that’s also just a hunch that I would have even if there wasn’t a lot of research to support it.

One thing that I find really interesting about this is how much of a backlash there often is.  The AAP, each year they update their guidelines, the American Association of Pediatricians.  They’re the ones who recommend no screen time under 2 years of age.  There are actually a lot of other groups that recommend that, too.  But each year when they publish them, there’s a huge, huge backlash.  I mean, there are articles on The Huffington Post and in women’s magazines, etc., from people saying this is ridiculous, it’s unrealistic, how can we be expected to parent without electronic media?  There are a lot of people who chime in and say that they don’t think that technology is harmful.  People are, of course, entitled to their opinions, but my question for them is, what is your opinion based on?  It’s one thing having an opinion, it’s another thing having an informed opinion, and there’s a lot of research, only a fraction of which we’ve gone over today, that suggests that there is harm to these technologies, especially when they’re used by kids under 2 years of age.  And there’s even a documented phenomenon, which I came across in one of the studies, that I thought was pretty fascinating called the third-person effect, which means that teenagers and adults often think that media influences everybody except themselves or their kids.  So when they interview people in these studies, they’ll acknowledge that media probably does influence people in these ways, but they think it doesn’t apply to them or their kids.  And again, all the research suggests that none of us are immune to these effects.

So I think that’s all I have to say about this.  Based on the reaction to things that I’ve posted along these lines in the past on Facebook, I imagine people will have some strong thoughts about this, so let’s open up a discussion on the comments thread of this podcast at my website, and I really do want to hear your thoughts about it, and I’m curious to see also any research that people want to share that might support a different viewpoint than the one that I presented here.  But yeah, let’s talk about it a little bit and talk about what the effects of this stuff are, maybe what your reactions to this are, what comes up for you when you listen to it.  Do you feel like there’s no way that you could change things, that multitasking is a fact of life for you and it’s just nonnegotiable?  Do you feel like it’s just impossible not to use electronic media for kids under 2?  I’m just curious.  I’d love to hear everyone’s thoughts, so let’s open up the discussion.

Steve Wright:  Aww, shoot.  Chris, what were you talking about?  I got lost in YouTube and my phone… sorry.  No!  I thought you hit a really good point there about how it’s almost a need now to schedule alone time.  I’m not good at it, for sure, but I know that when I have those days where I do have no screen time and alone time… and trust me, I’m kind of like you probably, where I have a queue of things I want to listen to on my phone, so even when I might have alone time, I’m too busy listening to some history podcast or health podcast or something.

Chris Kresser:  Yeah.  One of the biggest gifts of meditation for me is just the regular opportunity to just sit there and do absolutely nothing, just be completely alone with my sensations and thoughts and feelings and breath.  Earlier before we had Sylvie, I used to go on regular retreats, and that was even better because I got to do that for 10 days or even as much as 30 days.  Of course, that sounds like absolute torture to some people!  But it’s an incredible gift and opportunity for me, and I’m looking forward to it.  I think now that Sylvie’s getting a little older, both Elanne and I might be able to start going on retreats again.  That’s been a big part of Elanne’s life as well.  So yeah, I think that people do recognize this, of course, and know it in their own lives.  I mean, outdoor sports are really popular, and if you go rock climbing or hiking, things like that, of course, those are all opportunities to be in this kind of state that we’re talking about.  But given the reduction in the amount of time that people are spending in nature and the kind of perpetual increase in screen time, I just think it’s something that we need to bring our awareness to, and I think it’s actually probably a significant contributor to some modern diseases, and it’s just that it hasn’t really been talked about all that much in the public.

Steve Wright:  Well, I will say that I think that since we’re airing some of our dirty laundry about our habits, I think it’s rewired my ability to read books because when I was a kid, I would read a Hardy Boys book from start to finish and get that thing done in a few days, but I can tell you right now I’m in the middle of, like, six books, so I’m an ADD book reader right now.

Chris Kresser:  Yeah, and you’re not alone.  Like I said, Nicholas Carr was interviewing people who do that for a living, they read and write books for a living, and a lot of these folks are finding it really hard to finish books or even start books.  So I think you’re a step ahead of the game as far as that goes!

Yeah, so again, no judgment here, just questions.  I think there’s no downside to being aware, keeping our eyes and ears open, learning about this research and thinking about how we might make changes in our life that aren’t drastic, necessarily, or dramatic, but that do maybe mitigate some of the impact of this stuff in our own lives and in our kids’ lives.  Sylvie is almost 2 now.  She’s 21 months, and she really has had almost no exposure to screens.  That’s just the decision we made early on, and the exceptions to that are that we will occasionally do a video Skype with my parents or with Elanne’s parents, so of course, there’s a little bit of screen time there, but outside of that, she doesn’t have any screen time.  And I’ll tell you, there have definitely been times where we’ve been like:  Let’s just put her in front of the TV!  Where we’re going nuts or we’re at the end of our rope and we just wish we could plop her in front of the TV and turn it on and have it babysit her, but always in the back of my mind there was that kind of nagging voice that had read all the research that I’ve read about that.  And surely doing that a few times isn’t going to make a big difference, but I felt like it was kind of a slippery slope, and if we did it a couple of times, we might get pretty addicted to it, so we’ve just avoided it.  You know, this is the sample size of n=1, we have nothing to compare it to, and I wouldn’t even begin to try because it’s ridiculous, but I at least know that it’s possible.  And of course it’s possible because we were all raised and there were lots of generations that came before us that were raised without any access to screens.

Steve Wright:  Well, I commend you on that because I know a lot of people who would have a really hard time doing that.  And I don’t have any experience with kids, but I can tell you that that would definitely be difficult.

Chris Kresser:  Yeah, 90%, so I’m in the minority for sure, and once again, it’s not a value judgment.  It’s just something to continue to be aware of.  I think that’s it.  We’re coming up to an hour here.  Like I said, I’d like to hear your comments on both the vitamin D issue and the electronic media and rewiring our brain issue, and next time, I know we have a lot of questions.  Steve asked me to let you know that we have over a hundred questions in the backlog, and we’ll try to get through them.  It’s hard because I only do this twice a month and occasionally I have things I want to talk about like this, so I realize we don’t make as much progress as some other Q&A-oriented shows that are going four times a month.  So thanks for your patience and thanks for continuing to send in your questions.  At the very least, even if I’m not able to answer them, it tells me what all of you are thinking about, what’s important to you, and that actually helps me craft the show, so please do keep them coming.

Steve Wright:  Yeah, and thanks for listening.  I think it’s been a great show, Chris.  Thanks for broadening my horizons both on what the Internet is doing to me and furthering this vitamin D thing because I think everyone is so quick to jump on the black or the white side on all these health issues, so just keeping an open mind and remembering that it’s such a gray scale on all these issues, I think, is really important.

Chris Kresser:  Yeah, I think so, too.  And let us know what you think of the audio quality, too.  We’d love to hear from you about that.

Steve Wright:  Awesome.  Well, thanks, everyone, for listening to this show.  Again, as Chris mentioned, please keep sending us the questions.  We get them; we read them all.  You can send us more questions at ChrisKresser.com using the podcast submission link.  And if you enjoyed listening to the show, especially if you’re doing this on iTunes right now, please head over to the iTunes Store and leave us a review.  It helps boost our rankings in iTunes, and lets other people listen to the show, kind of spreads the word about it.

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Join the conversation

    • Oops, my bad, I looked again and saw I didn’t pay close attention to the units. 115 nmol per liter is 46 ng per ml. Apologies.

  1. This article is quite old now, not sure if you’re still monitoring comments.

    I was wondering if it’s possible to take too much, or overdose, on Vitamin D?

  2. I just listened to this podcast (two years late), and wanted to comment on the Vit D. My Vit D levels test in the “normal” range, but I suffer from severe seasonal affective disorder and “chronic boredom” depression. As in, my depression doesn’t look like sadness, but rather feeling like everything is boring, having no motivation to do anything, wanting to quit my job but nothing else sounds interesting either, not wanting to get out of bed to start the day. These feelings are must much worse in the New England winter than in summer months on bright days. I take 4,000 IU of Vitamin D daily, and it does wonders for my depression. If I miss it for a few days, I get back into that slump. I’ll grant that sunlight is better than pills, but for much of the year in Boston, there is no sunlight–days are 7 hours long and completely overcast for weeks on end. My point in all of this is that blood levels aren’t everything–some need more of a nutrient than others for proper neural (or other) functioning. My theory for my own particular case is that I am homozygous for a Vitamin D Receptor (VDR) polymorphism, which decreases the rate at which my dopaminergic neurons take up Vitamin D, which leads to decreased dopamine synthesis, which results in my particular brand of depression. But whether or not my theory is right, I know that taking Vit D helps me and will continue to do so.

  3. Chris, thank you for such awesome info! LOVE what you’re saying and what the research is saying about technology — it makes so much sense. I already have all notifications turned off on my phone, ringer off, try not to carry my cellphone 24-7. My brain and body are immediately different in a good way when I have a day away from the computer and phone. It’s frustrating to me that it’s hard to have any career today where you don’t NEED to be online. Having grown up in the 80’s and 90’s I know what it was like not to have all of this technology and it was sooo much better! I wish people would realize that for all that is gained, you have to use all this technology in moderation or else the losses outweigh the gains.

  4. “They’re not always what you would expect them to be, in part because of these polymorphisms and in part possibly because of disease states that cause an over-conversion of 25D to 1,25D, the active form, that happens in some autoimmune diseases. ”

    Would this cause the 25D levels to be low then? Or high?

    I ask because I just had my vitamin D levels tested, and my 25D was at 41. My provider was very surprised, she had never seen those levels before in someone that does not supplement. I am a 32 year old caucasian woman living in the Northeastern USA. I do not supplement vitamin D. I eat mostly paleo, lots of sardines, and occasionally do take high quality fish oil. I get lots of sun as often as I can.

    Are these levels considered “normal” or “ideal”? I was really excited about my results, but this article has me wondering about it.

  5. I think the points that Chris makes about vitamin D are very well-reasoned and I appreciate and agree with his skepticism about following the recommendations of the vitamin D Council.

    Vitamin D is a prohormone and an immunomodulator. As it has no taste and one can easily eat enough vitamin D to kill oneself it would appear that we are not designed to consume large quantities of it. This suggests to me that oral supplementation in the vast majority of cases is unwise.

    In addition there is good evidence that significant supplementation with vitamin D may be a factor in allergic disease. Here is a journal article on this: http://www.ncbi.nlm.nih.gov/pubmed/15699498

    Also there is some evidence that significant supplementation with vitamin D could be a factor in inducing autism: http://omicsgroup.org/journals/infant-exposure-to-excessive-vitamin-d-a-risk-factor-for-autism-2165-7890.1000125.pdf In interest of full disclosure, I am the author of the latter article.

  6. This is a great podcast, it was informing about the vitamin D levels I had no idea fair skinned people got that many IU’s of vitamin D with such little exposure.

    Also, I agree with the technology re-wiring the brain, I’ve de-activated facebook and my focus and productivity has went up immensely, not to mention my mood is far better. I’ve always been under the presumption that we are sponging and will soak up whatever is around us. So just de-activating facebook and all the quips of different sorts being out of my life has done wonders for me, and I’m very hesitant to re-activate it full time, and if I do I will definitely batch my time with it like emails.

  7. Chris, at this point, are you still recommending supplementing with Vitamin D – especially if ones levels fall in the 20s? I’m really confused as to what to do. I take CLO/BO blend, and now I’d like to leave it at that. Wondering what you’re doing at this point, in general terms.


  8. Hi Chris, what’s the reference of the vitamin d article? Thanks for all the great info.

  9. I’m very interested in the actual study being referenced here. Can you point me to it online?

  10. Here’s what I am wondering about the vitamin d topic:
    Perhaps the optimal numbers (25 to 35) should be thought of as the average over a full year. In other words, levels will be higher in the summer months, and then lower in the winter, leading to a good balance.

    My sense is that one should get a lot of direct, noon sunshine in the warm months, reaching quite high vitamin d levels in those months, then do NO supplementing in the winter (other than cod liver oil, let’s say), dipping to low levels.

    Over the year, one would probably be exactly in the target zone overall.

  11. Chris, you mentioned wellness retreats on this podcast! I am looking for one that isn’t strictly Vegan and it’s not easy. Do you or anyone else reading have any suggestions on good places? Organic food, yoga, spa, meditation…

    Thanks so much to anyone with suggestions!


  12. Since my own brain injury in May 2011, I have begun studying neuroscience; and the research that I have done shows that our brains are adapting and changing, but it is not necessarily a bad thing. Chris, I know you didn’t say that it was one way or the other, just that it is, and indeed it is.

    I started reading a book called “The New Brain” by Richard Restak, MD about this very topic of how this technology is re-wiring our brains. And even before my brain injury, but more so now, there are many books that I have started but have not finished. I wrote an article about this aspect of our evolution in a post called “Biology, Evolution, and The Brain.” In this article I talk about feeding the brain as well as my own experience with a brain injury, and I wanted to share this part about brain evolution:

    “Human evolution as it relates to digestion follows the same form of evolution as other species. There are many aspects of human evolution, however, that are quite unique. Our evolution has reached new frontiers because we, unlike any other species, have begun a form of cultural and social evolution. Teaching and learning is the basis of this intellectual evolution. Through the inventions of language, writing, and communication, our ability to intellectually evolve has grown more than exponentially. The power of books, the power of written language and the dissemination of ideas, and how these are uniquely human and profound methods that have accelerated this evolution is quite impressive. In a more in depth manner and unlike any other species, we have the ability to spread knowledge and ideas to one another. We are able to show our offspring how to play a sport or an instrument, how to drive a car, or even how to read a book. And from books, one can learn more. We are far more than ‘merely apes.’

    Today, GPS allows humans to locate where on earth they are standing or where someone or something else is. Artificial Intelligence (AI) is getting better to be able to do everything from driving a car to translating text from one language to another; breaking down language barriers to our abilities to communicate with one another. All of these and more allow the rate at which we culturally evolve to further grow.

    What has accelerated our intellectual evolution to an entirely new level is the Internet. With the advent of the Internet, an idea or lesson can be transmitted fom one side of the globe to the other in less than a second. Thus, communication is even more widespread, and therefore, so is the rate of our cultural evolution.

    Online classrooms take this to an even more profound level by allowing anyone with an Internet connection to learn from a university like Duke, Princeton, Harvard, or currently 30 other top universities for free. I have been taking courses using this incredible infrastructure for about six months now, and I hereby declare coursera.org the best new thing in the world right now!

    Because our intellectual evolution is based around teaching and learning, understanding the ways in which one is able to learn opens the door to allow them to learn more. Since my brain injury (and to a lesser degree before), I have had trouble staying focused on written text. I suppose my experience is that I will begin to read something, and after only a few minutes, my entire being feels as if it is pulling me from the page. I begin to think of what I need to do, what tomorrow has in store etc… As if I have a need to interact with my environment rather than to stare at words on a page.

    This is a difficult position to be in, especially when I am very interested in the book or article that I am attempting to read. John Medina compiles a lot of brain studies in his very smart book, “Brain Rules”. He says “Hear a piece of information, and three days later you’ll remember 10% of it. Add a picture and you’ll remember 65%.” No wonder most people watch TV far more than they read. This makes a lot of sense, but also makes me a little sad because I enjoy writing, and so much information is in written form.

    It may be because of my brain injury, but I have personally found that I learn better when I listen rather than read. This is why I intend to make an audiobook version of my story. I have found methods that help me to understand more effectively, but I am completely aware that other people learn better using entirely different methods. This subject reminds me of an earlier post: Learning How to Learn. Surrounding my own difficulties reading, it could possibly be a result of my brain injury that pulls me from the page every time that I attempt to read… Perhaps some people simply learn better when they see or hear something rather than read something… Or perhaps it is the animal instinct (or Paleolithic man) within us all.”

    Read the whole article here:

  13. I was on 10,000 IU D for years and my dr. now has me on 5,000 per day. I am concerned about it. I have Hashimoto’s with RT3. Could the high D contribute to my RT3?