In a previous article1, I suggested that nut consumption should be limited or moderated because of the high levels of omega-6 fat many of them contain. But there’s another reason you shouldn’t make nuts a staple of your diet.
One of the main principles of the Paleo diet is to avoid eating grains and legumes because of the food toxins they contain. One of those toxins, phytic acid (a.k.a. phytate), is emphasized as one of the greatest offenders.
But what is often not mentioned in books or websites about the Paleo diet is that nuts are often as high or even higher in phytic acid than grains. In fact, nuts decrease iron absorption even more than wheat bread2. This is ironic because a lot of people on the Paleo diet – who go to great lengths to avoid food toxins – are chowing down nut like they’re going out of style.
What is phytic acid and why should we care?
Phytic acid is the storage form of phosphorus found in many plants, especially in the bran or hull of grains and in nuts and seeds. Although herbivores like cows and sheep can digest phytic acid, humans can’t. This is bad news because phytic acid binds to minerals (especially iron and zinc) in food and prevents us from absorbing them. 3 Studies suggest that we absorb approximately 20 percent more zinc and 60 percent more magnesium from our food when phytic acid is absent4. It’s important to note that phytic acid does not leach minerals that are already stored in the body; it only inhibits the absorption of minerals from food in which phytic acid is present.
As most people following a Paleo diet will probably have heard by now, diets high in phytate cause mineral deficiencies. For example, rickets and osteoporosis are common in societies where cereal grains are a staple part of the diet.5
How much phytic acid should you eat?
Before you go out and try to remove every last scrap of phytic acid from your diet, keep in mind that it’s likely humans can tolerate a small to moderate amount of phytic acid – in the range of 100 mg to 400 mg per day. According to Ramiel Nagel in his article “Living With Phytic Acid”6, the average phytate intake in the U.S. and the U.K. ranges between 631 and 746 mg per day; the average in Finland is 370 mg; in Italy it is 219 mg; and in Sweden a mere 180 mg per day.
As you can see from the table below, 100 grams of almonds contains between 1,200 – 1,400 mg of phytic acid. 100g is about 3 ounces. That’s equal to a large handful. A handful of hazelnuts, which is further down on the list, would still exceed the recommended daily intake – and that’s assuming you’re not eating any other foods with phytic acid, which is not likely. Even the Paleo-beloved coconut has almost 400 mg of phytic acid per 100 gram serving.
[Disappointing side note for chocolate lovers: Raw unfermented cocoa beans and normal cocoa powder are extremely high in phytic acid. Processed chocolate may also contain significant levels.]
FIGURE 2: PHYTIC ACID LEVELS1
In milligrams per 100 grams of dry weight
| Brazil nuts | 1719 |
| Cocoa powder | 1684-1796 |
| Oat flakes | 1174 |
| Almond | 1138 – 1400 |
| Walnut | 982 |
| Peanut roasted | 952 |
| Brown rice | 840-990 |
| Peanut ungerminated | 821 |
| Lentils | 779 |
| Peanut germinated | 610 |
| Hazelnuts | 648 – 1000 |
| Wild rice flour | 634 – 752.5 |
| Yam meal | 637 |
| Refried beans | 622 |
| Corn tortillas | 448 |
| Coconut | 357 |
| Corn | 367 |
| Entire coconut meat | 270 |
| White flour | 258 |
| White flour tortillas | 123 |
| Polished rice | 11.5 – 66 |
| Strawberries | 12 |
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Can you prepare nuts to make them safer to eat?
Unfortunately we don’t have much information on how to reduce phytic acid in nuts. However, we know that most traditional cultures often go to great lengths prior to consuming them.
According to Nagel7:
It is instructive to look at Native American preparation techniques for the hickory nut, which they used for oils. To extract the oil they parched the nuts until they cracked to pieces and then pounded them until they were as fine as coffee grounds. They were then put into boiling water and boiled for an hour or longer, until they cooked down to a kind of soup from which the oil was strained out through a cloth. The rest was thrown away. The oil could be used at once or poured into a vessel where it would keep a long time.50
By contrast, the Indians of California consumed acorn meal after a long period of soaking and rinsing, then pounding and cooking. Nuts and seeds in Central America were prepared by salt water soaking and dehydration in the sun, after which they were ground and cooked.
Elanne and I have been preparing nuts like this for a few years, and I personally notice a huge difference in how I digest them. I used to have a heavy sensation in my stomach after eating nuts, but I don’t get that at all when I eat them after they’ve been prepared this way.
Another important thing to be aware of is that phytic acid levels are much higher in foods grown using modern high-phosphate fertilizers than those grown in natural compost.
So how many nuts should you eat?
The answer to that question depends on several factors:
- Your overall health and mineral status
- Your weight and metabolic health
- Whether you are soaking, dehydrating and roasting them nuts before consuming them
One of the biggest problems I see is with people following the GAPS or Specific Carbohydrate Diets, which are gut-healing protocols for people with serious digestive issues. Most GAPS and SCD recipe books emphasize using nut flour to make pancakes and baked goods. This is presumably because many people who adopt these diets find it hard to live without grains, legumes and any starch. While nut flours don’t tend to contain much phytic acid (because nut flour is made from blanched nuts, and the phytic acid is found mostly in the skin of the nuts), they can be difficult to digest in large amounts — especially for those with digestive issues. I’ve found that limiting nut flour consumption is necessary for most of my patients that are on GAPS or SCD. It’s also best to be moderate with consumption of most commercial nut butters, which are made with unsoaked nuts. However, some health food stores do carry brands of “raw, sprouted” nut butters that would presumably be safer to eat.
All of that said, in the context of a diet that is low in phytic acid overall, and high in micronutrients like iron and calcium, a handful of nuts that have been properly prepared each day should not be a problem for most people.
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Hi Chris
I’ve started on a diet for mass building, so I have been eating oats, brown rice,whole bread,whole pasta, peanut butter, and different peanuts types, every day, with meat, dairy and all other ‘healthy’ recommended stuff. I’ve been experiencing lots of bloating which did not happen before. Luckily I found this site were I found out that phytic acid may cause indigestion, and as you can see I was eating lots of that stuff. Do you think that might have caused my indigestion and bloating? Is there a way I can still eat them by soaking or other things? if not can you recommend something else I can have for carbs and fiber? thank you
I’m not a fan of phytates, as I’ve noticed a severe difference between the way I feel after drinking store bought almond milk (probably full of phytates) versus the sprouted nut milk that I make at home. (the store bought milk made me soooooo sick, I felt like I overdosed on laxatives).
But, Chris, why are there so many articles and studies that say people with a high phytate diet have less osteoporosis?? Are they influenced by the agricultural industry, because I don’t believe them.
David, in the podcast linked by Anna on the comment just above mine, he talks about how most phytic acid in food is already bound to a nutrient, so it won’t decrease the nutrient absorption we get from other foods, and therefore the amount of phytic acid in a certain food will mostly only decrease how much nutrient we can get from THAT food.
Florent,
Where exactly do you see that he changed his views?
Chris, since your views have changed on this topic, I think you should update this article.
I have only skimmed the comments, so forgive me if I am re-posting — but I would remind people that Chris has since presented more information on this topic. For a full perspective it would be good to read the section of this podcast transcript titled “The misconceptions about phytic acid”: http://chriskresser.com/rhr-what-science-really-says-about-the-paleo-diet-with-mat-lalonde
Chris, I believe you are a fan of the GAPS diet for gut healing, and I have a question re: NCM’s recommendations for nut intake. She doesn’t seem very concerned about anti-nutrients or PUFAs. Nuts are recommended, as are additional supplementary nut/seed oils, fish oils, and cod liver oil. To me, coming from a paleo background, that seems like a ton of PUFA. When you recommend GAPS to your clients, do you advise them to cut out the supplementary oils and nuts, aside from the CLO?
(Sorry if this is a little off topic, but wasn’t sure where to ask this question.)
Yes I would like to know the answer to this question too. I have started the GAPS diet and am really concerned with amount of nuts/seeds it recommends? I am getting confused and overwhelmed with all this info. I am also very underweight and don’t know how the best way is to gain weight on the GAPS as it is so carb limiting. What do you recommend for your clients that you put on the GAPS, what does your version of the GAPS diet look like?
I notice a lot of nuts aren’t listed here. What about phytic acid levels for macadamias, pistachios, hazelnuts or cashews?
Hi! Thanks for the info!
I have a question though which has already bothering me for a while. What happens to the “good fats” in the nuts when you roast them? Don’t they oxidate like it would be the case with olive oil, butter etc. when they get too hot?
Thanks in advance!
Nico
I’m so confuse and would love to hear your comments on this, so I will know if it’s safe to start binding on coconuts again.
Romiel Nagel posted this information in his article Living with Phytic Acid under MORE UPDATES
COCONUT AND PHYTIC ACID
I’m writing in regard to the article written by Ramiel Nagel titled “Living with Phytic Acid” (Spring 2010). In the article there are references to the phytic acid content of coconut. Since the publication of this article people have been asking me whether they should soak coconut or coconut flour to reduce the phytic acid.
Phytic acid occurs in nuts and seeds in two forms—phytic acid and phytic acid salts [Reddy, NR and Sathe, SK (Eds.) Food Phytates. CRC Press, 2001]. Both are generally referred to as “phytates.” Together, these two compounds make up the total percentage of phytates reported in various foods. However, they do not possess the same chelating power. So the chelating effect of the phytates in corn, wheat, or soy are not the same as those in coconut. You cannot predict the chelating effect based on total phytate content alone.
The mineral-binding effect of the phytates in coconut is essentially nonexistent. It is as if coconut has no phytic acid at all. In a study published in 2002, researchers tested the mineral binding capacity of a variety of bakery products made with coconut f lour. Mineral availability was determined by simulating conditions that prevail in the small intestine and colon. The researchers concluded that “coconut flour has little or no effect on mineral availability.” (Trinidad, TP and others. The effect of coconut flour on mineral availability from coconut flour supplemented foods. Philippine Journal of Nutrition 2002;49:48-57). In other words, coconut flour did not bind to the minerals. Therefore, soaking or other phytic acid-neutralizing processes are completely unnecessary.
Soaking has been suggested as a means to reduce the phytic acid content in grains and nuts. Some suggest coconut flour should also be soaked. To soak coconut flour doesn’t make any sense. The coconut meat from which the flour is made, is naturally soaked in water its entire life (12 months) as it is growing on the tree. To remove the meat from the coconut and soak it again is totally redundant. After the coconut meat has been dried and ground into flour, soaking it would ruin the flour and make it unusable. You should never soak coconut flour.
In the tropics coconut has been consumed as a traditional food for thousands of years. Those people who use it as a food staple and regard it as “sacred food,” do not soak it or process it in any way to remove phytates. It is usually eaten raw. This is the traditional method of consumption. They apparently have not suffered any detrimental effects from it even though in some populations it served as their primary source of food.
Bruce Fife, ND
Colorado Springs, Colorado
This also leads me to wonder if the chelating power is different, not just in coconut, but all nuts from the chelating effects of grains and legumes and also where you would find a list that defines the type of phytic acid in each food.
paleo encourages nuts because of the good fats and proteins in them. legumes and grains dont have that. while phytic acid does leach minerals, in a healthy person gut bacteria break down these componds to release the minerals for reabsorption. there is also some evidence of phytic acid being an antioxidant.
that said, everything good in moderation!
Thank you Mr. Kresser, for taking time to go on the UnderGround Wellness show. I appreciate the comments and information you provided and shared with all.
In that interview, you spoke about the numerous benefits of cold water fish. You also mention the potential negative effects of mercury (offset by selenium levels present in wild fish), and PCBs + dioxins.
I am currently reading Our Stolen Future and in it, multiple studies relate to the Great Lake fishes and their high levels of man-made chemicals. If I consider the arguments you gave in the interview with Sean, this should have little effects, however the studies revealed in the book show numerous negative effects on people and their 2nd and 3rd generation siblings (some physical illness, however the majority of the effects being hormonal). Moreover, the fishes studied did not include shark, whales, or tuna (not present in the Great Lakes).
I want to consume large amounts of fish…I understood when you spoke about EPA, DHA, ALA and that only 5 or 6% of plant based omega 3 is converted to longer chain fatty acids…but I am very hesitant and not convinced that cold water smaller fish are safe…
What to do?
One other question if I may? (sorry for the long email), omega 3, being especially long chain omega 3 fatty acids are especially sensitive to light, and heat. Exposing the fatty acids to such conditions would render them rancid very quickly and lose most of their benefits? If this is the case, wouldnt cooking fish make the beneficial fats in question rancid? What would be the best way to consume fish? (in order to preserve the sensitive fats)?
Ben
Dear Chris,
I have just read “Why Stomach Acid is Good for You” which you quote in your stomach acid blogs.
He says if we have high stomach acid levels then phytates are not a problem? Could you comment?
Also I would LOVE to know why we get low stomach acid as we get older? No one has addressed the cause.
Yes, some amount of phytate isn’t problematic, and it’s actually higher in foods like spinach than it is in nuts. That said, people don’t tend to overeat spinach, but the same can’t be said for nuts.
The main cause of low stomach acid as people age is probably increased rates of h. pylori infection.
Oh no! I eat a spinach and fruit based smoothie several times a week! How much would be over eating spinach? I found this article as I was deciding to increase my weekly nut intake (from its current ZERO!) and someone mentioned phytic acid. Thanks for sharing your knowledge!
The big problem with spinach is oxalic acid. Over consumption of okra, beet roots, chard, spinach and a few others can lead to kidney stones. Oxalic acid binds to calcium.
“Oxalic acid is a naturally occurring chemical in plants and animals and is also consumed in a variety of different foods such as leafy greens, nuts, seeds, most berries, certain fruits, soy and soy products, meat and dairy products. In large amounts, oxalic acid is poisonous, but toxic levels are not found in foods that we normally eat.
The main controversy surrounding oxalic acid in food is whether or not they contribute to the formation of kidney stones. About 80% of the kidney stones formed by adults in the U.S.A. are composed of calcium oxalate. Oxalic acid binds with other minerals such as calcium which form a salt known as an oxalate. Oxalic acid interferes with the absorption of calcium in foods because they bind with it, making it unusable by your body.”
http://www.incrediblesmoothies.com/green-smoothies/oxalates-spinach-oxalic-acid-health-concern/
I will mention kale because it is one of the lowest in oxalic acid. It also has about 3 times the A and C of other greens. So, because of the this C content maybe the effects are reduced.
Here is a link with amounts listed:
http://www.chameleonforums.com/blogs/sandrachameleon/215-oxalic-acid-content-vegetables.html
Chris, you say that “we absorb approximately 20 percent more zinc and 60 percent more magnesium from our food when phytic acid is absent”, but what about the fact that nuts often contain loads of zinc and magnesium? Wouldn’t eating nuts result in a net positive absorption of these minerals?
The point is that a lesser amount of nutrients will be absorbed unless the nuts are soaked to inactivate phytate.
Are you talking about the nutrients in the nuts or in the other ingested foods? I would find surprising that eating nuts would cause a total net loss in zinc absorption for the body given that nuts contain a lot of it.
As a previous poster said, thank you for this informative (and disappointing) article. I too have a heavy feeling when I consume nuts/nut butters and was surprised to see someone else put it into words like that. I tried to keep nuts in my diet in small quantities I guess because there is so much I don’t eat that I figured I should be able to, but I don’t like the way I feel when I eat more than a little. My question is about sunflower seeds: is this a good replacement? I don’t see them on the list…
In the June 13, 2012 Revolution Health Radio Show: What Science Really Says About the Paleo Diet, Mat Lalonde states at 26:28 “The misconceptions about phytic acid” that we do not need to be concerned about phytic acid at all. Is it possible that that is a conflict with this article?
I found this very thorough article: http://donmatesz.blogspot.com/2011/10/phytate-facts.html
It seems obvious that if someone is getting all their minerals in abundance, any amount of phytic acid can be great news. I’m a raw vegan (supplemented) and after my investigation here, I’m very confident about my diet choice. My skin looks great and a whole lot of health problems are solved. Now, I *really* appreciate my nuts!
Wow, that cocoa powder news is really depressing. I have some in my coffee right now. Wondering if boiling can effect the phytic acid content.
Hey Chris?
I usually have pumpkin and sunflower seeds in my muesli. What about them? Should I soak them? And how do you rate almond milk?
Thank you
Alex
So does anyone know if bananas are safe to eat? I LOVE them, but I am having trouble digesting enough zinc and magnesium as is, I need more not less! I’ve read somewhere else that Bananas contain no pyhtates (because theyve been bred to be seedless) is this true?
thanks, Benjamin
Nothing wrong with bananas. Unless, perhaps, you have diabetes.
A medium banana contains 35 mg of phytic acid. Fermentation and soaking reduce levels of phtates.