The Unbiased Truth about Artificial Sweeteners | Chris Kresser
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The Unbiased Truth about Artificial Sweeteners

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These three wooden scoops show different forms of sugar and artificial sweeteners.
Artificial sweeteners come in many forms, but are they good for you? Find out. iStock/MamaMiaPL

Note: This article was originally published in 2014 and was updated in 2018 to include the latest research. Several years ago, the evidence was limited, and I was hesitant to make a firm conclusion on the dangers of artificial sweeteners. However, I now believe there is sufficient evidence to suggest that artificial sweeteners should not be included in a healthy diet.

Artificial sweeteners continue to be a controversial public health issue, and the research keeps coming. On one hand, many people are adamantly opposed to the use of sweeteners like aspartame, sucralose, neotame, acesulfame potassium (Ace-K), saccharin, and advantame because of the purported link with increased risk for cancer and other diseases. But on the other hand, they’re becoming increasingly popular as people try to reduce calorie consumption and lose weight.

There’s too much research out there to cover comprehensively in a blog article, but I’ll try to include the basics: Will artificial sweeteners give you cancer or other diseases? Do they actually help with weight loss? And ultimately, should you be eating them?

To learn all about sweeteners—natural and artificial—download this free eBook today.

The research on artificial sweeteners has always been lacking—until now. So, are artificial sweeteners healthy? Find out in this article, updated in 2018 with the latest information. #nutrition #wellness #chriskresser

Will Artificial Sweeteners Give You Cancer?

Artificial sweeteners were first tied to cancer risk in the 1970s after a study showed that a combination of saccharin and cyclamate (another early artificial sweetener) caused bladder cancer in lab rats. The mechanism behind these effects was later found to be specific to rats and not generalizable to other animals or humans (in these rats, comparable doses of vitamin C can also cause bladder cancer), and further studies demonstrated that neither sweetener is carcinogenic. (12)

However, this study cast a shadow of doubt over artificial sweeteners, and thanks in part to the media’s penchant for blowing nutritional headlines way out of proportion, the reputation of artificial sweeteners has never recovered.

A later study suggested a link between aspartame consumption and brain tumors. The authors based this hypothesis on the fact that both brain cancer and aspartame consumption had increased since 1980—despite not knowing whether the people getting brain tumors actually consumed artificial sweeteners—and on a rat study where aspartame-supplemented diets led to the formation of brain tumors. (3)

This association has been more or less dismissed by the research community because three case-control studies have found no association between brain tumors and aspartame consumption, and subsequent animal studies haven’t been able to replicate the aspartame-induced brain tumors found in the original rat study. (4)

Artificial sweeteners have also been implicated in the development of lymphoma and leukemia, and one observational study found a weak link between artificial sweetener consumption and development of non-Hodgkin lymphoma and multiple myeloma in men, but not in women. (5) The study authors concluded that due to the inconsistency in their results, there isn’t likely a causal link, although it can’t be ruled out.

Artificial sweeteners have also been tested for associations with other cancers, including breast, pancreatic, stomach, colon, and endometrium, with no correlations found. (6)

Based on the evidence, I don’t think artificial sweeteners are a huge risk factor for cancer, although the possibility can’t be ruled out and caution is warranted.

Artificial Sweeteners Can Change Your Metabolic Health

Artificial sweeteners have also been tied to an increased risk for developing metabolic syndrome and related diseases such as diabetes and cardiovascular disease. Numerous observational studies have attempted to parse out a consistent association with disease risk, but for every study that has linked artificial sweetener consumption with metabolic syndrome, heart disease, or diabetes, there’s another that has found no association. (789)

Fortunately, we have meta-analyses, which serve to pool together similar studies and try to determine the overall effect. In July 2017, the Canadian Medical Association Journal published a meta-analysis that picked apart the findings from seven randomized controlled trials (RCTs) and 30 cohort studies on artificial sweeteners. (10) In total, the studies followed more than 400,000 people for about 10 years.

In the RCTs, artificial sweeteners had no significant effect on cardiovascular or metabolic disease risk. However, in the long-term cohort studies, consumption of artificial sweeteners was associated with a higher incidence of type 2 diabetes, metabolic syndrome, and cardiovascular events, even after controlling for confounding variables.

Of course, observational studies cannot confirm causality, but another study, published in the journal Nature, showed that artificial sweeteners altered the gut microbiota and that this was causally linked to glucose tolerance in mice. (11) For the humans included in the study, even just one week of artificial sweetener consumption was enough to reduce glucose tolerance in half of the participants.

It’s clear that artificial sweeteners can have an impact on your gut microbiota—and that can have far-reaching effects on your health.

For a complete breakdown of how this works, check out my 2016 article “How Artificial Sweeteners Wreak Havoc on Your Gut.”

Pregnant Women: Avoid Artificial Sweeteners, Just to Be Safe

There has been concern in recent years over a potential link between artificial sweetener consumption and pre-term delivery, prompted by two observational studies published in 2010 and 2012. (1213)

These studies have significant limitations:

  • The associations are small and not linearly dose-dependent;
  • Not all artificially sweetened beverages were accounted for; and
  • Women who consume more artificially sweetened drinks also tend to smoke more and have higher BMI and lower socioeconomic status. (14)

All told, the risk seems small, but I would advise pregnant women to avoid artificial sweeteners just to be on the safe side.

The Big Question: Do They Help You Lose Weight?

For most people, the primary motivation for consuming artificial sweeteners is a desire to eat fewer calories and lose weight. But do artificial sweeteners actually help achieve that goal? Yet again, the evidence is mixed.

Many observational studies have found a positive association between artificial sweetener intake and obesity, but in this situation, reverse causality is particularly likely. (15161718) In other words, while it’s possible that artificial sweeteners contributed to weight gain in these studies, it’s also possible that people who are overweight are more likely to choose diet beverages and other artificially sweetened foods in an effort to lose weight. We also have a decent number of clinical trials testing the weight loss effects of artificial sweeteners in humans, although many are too short term to have much practical significance.

In one study, overweight subjects were given supplements of either sucrose or artificial sweeteners for 10 weeks. (19) At the end of the trial period, subjects in the artificial sweetener group had experienced, on average, a reduction in weight, fat mass, and blood pressure, while subjects in the sucrose group gained weight and had increased blood pressure.

A study published in 2014 on weight loss and artificial sweeteners was surprisingly positive: over a 12-week period, participants who were instructed to drink 24 ounces of artificially sweetened beverages every day actually lost more weight than participants who were instructed to drink 24 ounces of water daily. (20) (It’s worth noting that this study was fully funded by the American Beverage Association.) Other trials have also shown successful calorie reduction and weight loss in participants who consumed artificial sweeteners (usually in the form of beverages). (212223)

So what do we make of all this? Fortunately, the same meta-analysis I mentioned above of over 400,000 people also looked at weight loss. (24) When they pooled together the seven RCTs, they found no significant effect of artificial sweeteners on body mass index (BMI). On the other hand, when they pooled the cohort studies, consumption of artificial sweeteners was positively associated with increases in weight, waist circumference, and a higher incidence of obesity.

Based on this evidence, it seems that artificial sweeteners do not necessarily lead to weight loss, and may in fact do the opposite!

As I mentioned, artificial sweeteners’ ability to disrupt the gut microbiota can lead to weight gain, but that’s not the only mechanism involved here. These sweeteners can actually “confuse” your body and make it harder for you to shed extra pounds.

How These Sweeteners “Confuse” Your Body

For most of human history, sweeteners were inextricably tied to caloric density. Our sweet taste receptors evolved primarily to help us identify calorie-rich food sources. So imagine the confusing results when our taste receptors are bombarded with sweetness without that expected surge in calories.

Animal models certainly indicate that artificial sweeteners can impair the innate ability to regulate caloric intake. Rats who are fed with artificial sweeteners consistently gain more weight than rats who are fed with glucose or sucrose. (2526) Additionally, the rats don’t tend to lose the excess weight, even after their diets are switched back to glucose or sucrose to reestablish the normal connection between a sweet taste and calorie-rich foods.

Interestingly, rats who were given stevia solutions gained significantly more weight than the glucose-fed rats and similar amounts of weight to the saccharin-fed rats. (27) Rats fed with artificial sweeteners also develop an impaired ability to respond to sugar-containing foods. In one study, rats who had been fed artificial sweeteners were unable to compensate for the calorie content of a sugar preload by eating less chow afterwards, while rats who had been fed sugar-containing food compensated almost perfectly for the extra calories in the preload by eating less chow. (28)

Rats that have been conditioned with saccharin also display a reduced thermic effect in response to consumption of a caloric sugar-containing meal, as well as higher blood glucose, compared with rats who had been conditioned with glucose. (2930) Additionally, saccharin-fed rats secreted less GLP-1 (which is implicated in satiety and glucose homeostasis) when given a sugar-containing test meal. (31)

Unfortunately, although the animal evidence is fairly robust, evidence in humans is limited. However, two interesting studies that used MRI to measure brain responses to sucrose solutions indicate that artificial sweeteners may alter the brain’s response to sweet tastes in humans. In one study, people who regularly consume artificially sweetened drinks had higher reward responses to both saccharin and sucrose compared with people who don’t consume artificial sweeteners. (32)

Additionally, people who don’t consume artificial sweeteners had different brain responses to the saccharin and sucrose, while those who regularly consume artificial sweeteners responded the same to both sweeteners. Another study found that the amygdala’s response to sucrose consumption was inversely related to artificial sweetener use. (33) (The amygdala is part of the brain that is involved with taste–nutrient conditioning.)

Should You Be Eating Artificial Sweeteners?

To sum up, artificial sweeteners are extremely new to the human diet, and for modern, industrial foods, the operating principle should always be “guilty until proven innocent.” We’ve conducted what are essentially population-wide experiments with the introduction of other industrial foods (such as high-omega-6 vegetable oils) because the initial evidence seemed promising, and we can see how well that worked out.

Increasing evidence from animal studies and human observational studies points to a link between artificial sweeteners and an increased risk for:

  • Glucose intolerance
  • Weight gain
  • Diabetes

Observational evidence also suggests a link between artificial sweetener consumption and cardiovascular disease risk.

While we have limited causal evidence in human clinical trials, I believe the evidence is strong enough to conclude that artificial sweeteners should not be included in a healthy diet.

In case you missed them, be sure to check out parts one and two of this series.

195 Comments

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  1. Recently sucralose (Splenda) has been detected in the river downstream from my city. Most of what we take in is excreted and doesn’t seem to break down in the environment. Something else to consider…

  2. Over the years I’ve found that if I drink too many diet sodas I end up binge eating later in the day, usually on simple carbs.

  3. Some time this spring I decided to just skip almost all sweeteners. Since I prepare most of my meals from scratch this isn’t hard–if I want a sweet treat I can always add banana or mango or something naturally sweet.

    Along the way I learned how to taste food again, and came to the realization that sugar was masking the true flavor of most foods. I’ve learned to enjoy the taste of food all over again. My chocolate is 85% pure and I’ve never had anything but black coffee as well.

    I found that the more sweets I eat, the more I crave. The less I eat, the less I crave. It didn’t take long (weeks) to eliminate the cravings. So I have no use for artificial sweeteners at all.

    Clearly though everyone is different, and it could be some people just decide they can’t live without sweeteners or they simply haven’t tried. It seems the artificial sweeteners are marketed to this group.

  4. I do avoid artificial sweetness at all cost. Sure the research may show they aren’t particularly harmful, but they way I see it they aren’t helping my diet either. They are typically found in food that do not add much if any nutritional value to my diet!
    Chris, have you seen any research linking artificial sweeteners and allergies such as skin and seasonal? I know of 3 clients who have cleared up skin and seasonal allergies by eliminating artificial sweeteners and I have had no luck finding scientific literature on this! As always, thank you for your wonderful work!

    • You say that as if “anecdotes” were a bad thing? 🙂 Anyway, I have pasted a number of quotes from recent peer-reviewed science articles as replies to various other comments above, have a look. Of course, they are just anecdotes from a laboratory setting, where the scientists were influenced by their socio-cultural setting, but still….

    • published research is just approved, “supervised” anedoctal evidence.
      also–that has made it past the PC committee of the journal; much research never even gets published, let alone funded and therefore DONE. all becuz it doesnt go with an industry or two’s agenda.
      how MY body reacts is the very most important thing. caveat emptor.

  5. My husband cut out diet drinks and quickly lost 15 pounds and his migraines went away almost completely. We will never go back to drinking them. I prefer to drink things with actual nutrients.

  6. Artificial sweeteners have no upside and unquantified downside risk. Logic dictates to avoid consuming them.

    I like bacon better than diet soda pop anyway 🙂

  7. I’ve taken what I think is the prudent Paleo approach to sweeteners and largely try to avoid them all, artificial OR natural. Sure, our ancestors probably loaded up on honey when they found it, but it was most likely an infrequent occurrence and not without stinging repercussions. There is so much sugar, HFCS, and fructose added to almost every imaginable food today, even where you wouldn’t expect it, so purposely adding any to my diet seems unwise.

  8. If you think artificial sweeteners are bad for you, try reading the research on actual sugar/sucrose, which can be the cause or exacerbate every known human disease. It’s stickiness isn’t just noticeable when you spill it on the floor or other places; you should have a look at your arteries and see how it sticks things together that should flow freely. A “little” of any artificial sweetener that doesn’t give you a headache, joint pain, or diarrhea is better than sticky arteries and high blood glucose.

  9. I used to drink diet sodas religiously to try and lose weight. I drink lots of water, too, but something about the carbonation, I guess, just gives that extra burst. Anyway after years of drinking them and years of medical issues, I went to see a holistic doctor. She told me to eliminate the artificial sweeteners and if I wanted soda, drink the ‘real stuff’. I was so afraid it would make me gain weight after having drank the diet soda for so long. Guess what? I didn’t see ANY evidence whatsoever. Very happy to use real sugar again and eliminate the artificial stuff, who needs it anyway? Why not stick with something ‘natural’?

  10. Well, there you have it, folks. I’m far more inclined to go with the anecdotal evidence, in this case. Read the other responses and its quite obvious that chemical sweeteners are bad news and should be avoided. I am going to do my own bio hack on blood glucose with stevia and xylitol…..good idea!

  11. Unlike most of your readers’ comments, I am (again) left with a disappointment regarding your vague mishmash of inconclusive hand-wringing.

  12. One Diet Coke can lay me out with a monster headache for days. The first time I tried one, I had been working in the yard at my parents house and drank half a can. Within 15 minutes, I felt like a red hot poker was being shoved into my left eye. If I end up with a migraine these days, it’s usually because i mistakenly ate something with aspartame or MSG. I don’t care what the studies show… the stuff is poision to me.

  13. One area of research not showing up is the artificial sweetener’e affect on other diseases. I have rheumatoid arthritis. While I am not a soda drinker to begin with, on the occasions I did drink one I began to drink diet, just to keep calories down. Within an hour I would have a severe arthritis attack. I tried this several times and the results were the same. Regular soda does not have that affect; consequently I surmised it was the artificial sweetener that caused the problem.

  14. I think we need a new term for sugar alternatives than “artificial sweeteners” because xylitol, stevia, etc. can arguably be considered “natural” and because some of the sugar alternatives likely have different effects on the body than others.

    • I call those sugar alcohols. Most are terrible tho. The only ones i’d ever consider are erythritol and maybe xylitol.
      I only use them for my nongrain baking and green smoothies as i pack in the greens, like 3c for one shake and dont want to waste my fruit allowance on sweetening it. It doesnt work anyway. Still needs to be sweetened to get the smoothie down. so i just use stevia (the only true “sugar alternative” IMO) and maybe erythritol with it and EAT my fruit, thus consciously enjoying it. i am everything-free at this point lol (and its having no effect STILL sigh) So bringing some joy to my eating is very needed!

  15. Thanks for the article Chris! I was literally talking with my boyfriend about this just yesterday. He was saying that drinking an artificial sweetener (say dissolved in a soda) has a different mechanism than consuming it in sold form. Have you seen any evidence of this?

  16. For me, personally, I notice that the consumption of artificial sweeteners gives me a headache/migraine. The more I drink the worse the headache. This article has amazing timing. After another bout of headaches I’m removing these products from my diet for good.

  17. I use hazelnut stevia in my one cup of organic coffee with cream each morning. I have used a small amount of stevia every day ever since it came out. I gave up my one diet Sprite a day, 2 years ago. Cancer runs in my family so I am always concerned about that! I have never had any adverse effects (that I am aware of), but am now cautious about Stevia. I do not want to switch to sugar, but have been reading Sweet Poison and am curious about dextrose, which does not contain fructose, only glucose.

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