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.
Better supplementation. Fewer supplements.
Close the nutrient gap to feel and perform your best.
A daily stack of supplements designed to meet your most critical needs.
When would be the best time to eat chocolate/nuts if we want to lower their bad effect on mineral absorption?
On an empty stomach. But if you just eat a moderate intake overall, it shouldn’t be a problem.
Thanks Chris 🙂 Who says there’s no “Undo” on the Internet?
Tara (and anyone else wondering after reading Tara’s question): Yes, Chris spoke about soaking and drying nuts to remove the phytic acid.
I just trashed the last few comments. Play nice, everyone.
Robin H: Thanks, and agreed – text can get you into trouble way too easily!
Interesting article. If you soak and dry (or sprout) nuts and seeds will this process neutralize toxins like phytic acid? I know this germinating process neutralizes the enzyme inhibitors making them easier for our bodies to ingest and absorb (per Dr. Edward Howell’s book, Enzyme Nutrition). What do you think?
Chris,
I was reading Ramiel Nagel’s article on phytic acid and after scrolling through the comments I came across this particular comment. I’m interested on your thoughts.
“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
Hello,
This is a controversial subject. Taking vitamin c with nuts can inhibit phytic acids ability to bind iron. In those of us over 40 is iron binding a bad thing? If nuts are eaten as a standalone snack are they binding minerals? If I take a multi mineral away from nuts and eat lots of green leafy’s would I develop mineral deficiency’s? And what about the benefits of phytic acid?
Therapeutic uses
Phytic acid may be considered a phytonutrient, providing an antioxidant effect.[1][21] Phytic acid’s mineral binding properties may also prevent colon cancer by reducing oxidative stress in the lumen of the intestinal tract.[22] Researchers now believe phytic acid, found in the fiber of legumes and grains, is the major ingredient responsible for preventing colon cancer and other cancers.[1][23]
In vitro studies using a cell culture model have suggested phytic acid may have a neuroprotective effect by chelating iron.[24] Similar types of cell-culture studies have found phytic acid significantly decreased apoptotic cell death induced by 1-methyl-4-phenylpyridinium. Phytic acid, at least in rodents, is known to cross the blood-brain barrier,[25] and so, there is a strong possibility that neuroprotection occurs in vivo as well.
Phytic acid’s chelating effect may serve to prevent, inhibit, or even cure some cancers by depriving those cells of the minerals (especially iron) they need to reproduce.[1] The deprivation of essential minerals like iron would, much like other systemic treatments for cancers, also have negative effects on noncancerous cells.
A randomized, controlled trial in breast cancer patients showed no effect on chemotherapy-induced anemia or tumor markers, but the patients reported subjectively feeling better.[26]
Phytic acid is one of few chelating therapies used for uranium removal.[27]
It has been shown to be a required cofactor for YopJ, a toxin from Yersinia pestis.[28] It is also a required cofactor for the related toxin AvrA from Salmonella typhimurium[28] as well as Clostridium difficile Toxin A and Toxin B.
As a food additive, phytic acid is used as a preservative, as E391.[29]
Thanks Ron for all the neat things on phytic acid!
“If nuts are eaten as a standalone snack are they binding minerals?”
I tend to eat my healthy portion of nuts (almost every day) as a snack, with only an apple to compliment them. I figure if there is anything to mineral loss, it’s happening only in this snack, not to the other meals I take, which have very little carbs, including breads/beans, in them.
So glad to hear about all the positives of phytic acid. At least I’m getting a good batch of it!
Bravo Ron, Exactly correct! I was going to post this and saw you did. Thanks.
Hi Chris,
I often put 10 (or so) almonds in my water bottle and drink out of my water bottle throughout the day while the almonds are soaking, by the end of the day the water tastes very much like almonds. Is this okay to do?
Thanks! S
Lots of people do lots of stupid things, it they choose to not follow the diet that they subscribe to, then that shouldn’t reflect on the diet. One might suggest that if they haven’t actually read the diet(and therefore would know the ratios in which something should be consumed) or they don’t follow the diet they have read… then in theory they are not really on the said diet. I’ve read many a blog that spoke on the negative affects of nuts and seeds and yet told me nothing of the dangers grains and legumes. I actually like that your article addresses both. I think Paleo/GAPS often get a bad name though because people are not actually reading the diets. They are kinda just winging it. It’s like a game of telephone…things just gets farther and farther from the truth. GAPS says no more that 20 % of your diet should be nuts and seeds(and that’s after being soaked and prepared properly) Paleo most often suggest no more than 4 oz a day. Raw foodies however, don’t seem to have a limit on nuts and seeds.
The Paleo diet does NOT encourage eating large amounts of nuts. They are encourage only in small amonuts. Soaking., dehydrating and roasting nuts can greatly reduce the phytic acid content and removing skin reduces the tannins. Perhaps certain Paleo individuals eat more than they should. But that is not what the diet recommends.
That’s true in theory, but in practice a lot of people on a Paleo diet chow down nuts like they’re going out of style.
Wow! My doctor encouraged me to eat 3 or 4 Brazil nuts per day for the selenium. Any other good sources? I sure don’t want to eat those nuts anymore.
This has been a great post and follow-up comments!
Honestly, this news about phytic acid is somewhat disheartening. So, it’s in our beloved dark chocolate, our coconut and coconut milk, and our nuts as well. Great. It seems like the longer I do Paleo, the more items get removed from my menu. Somehow, I have to believe that concentrating on phytic acid content is analogous to focusing on seeing the trees instead of the forest. It just can’t be that important of a factor when everything is considered.
I agree, Wil! One problem with Science is it quickly outlines all the things you don’t know. That is depressing in and of itself. I think if you can manage a couple of good meals without much phytic acid intake, your digestion will get the nutrients into your body sufficiently so that then if you snack on nuts, or eat a meal with some grain, you aren’t robbed so much. And that is a pattern that somewhat healthy people follow anyway. Eat your chocolate and nuts as snacks! Only have one “carb” meal. You’ll still have a lot of phytate-free digestion going on, the way I see it.
Great article Chris. One other comment on nuts, and I appologize if someone commented on this, is the addictive nature of them. I have several individuals (including myself in the past) who find themselves experiencing a binge-like effect when eating nuts, similar to that experienced with sugary foods. This makes me cautious/suspicious of nuts and gives me another reason to avoid them.
I agree Caveman. I’m probably not alone in the fact that I do not EVER binge on eggs, cheese, meat or veggies. I just eat an appropriate amount and stop, as anything more would be disgusting. Nuts are the only thing besides high-carb or sweet foods (including stevia) where I lose touch entirely with how much my body actually needs. It’s frustrating, because I do feel that a reasonable amount of nuts in the diet may be a good thing, but I literally cannot keep them around very often as my daily calorie count probably goes up by almost a thousand. I try to purchase nuts that I don’t care for that much (which is ridiculous), so I can use small amounts in salads and not be tempted to eat them out of the bag. It’s an interesting mystery as to why certain foods cause binging tendencies and others don’t.
Thanks for all the great information. Several of you mentioned ‘roasting’ soaked and dehydrated nuts. Please give an idea of how you roast them as I am new to this and am learning that high temps damage fats, etc. How does one roast properly prepared nuts healthfully? (Thanks)
Any idea why eating cashews (after being soaked and dehydrated) would cause extreme itchiness in my eyelids. I can tolerate soaked/dehydrated almonds, pecans, sunflower seeds.
I must eat a handful of soaked/blanched (to make skins easy to remove/ dehydrated almonds daily to help with bowel activity. Because I can’t tolerate cellulose I can’t take most magnesium pills. Though I did find a straight powder, the nuts seem to work better.
I didn’t know about the roasting but wonder if the blanching achieves the same effect.
Sounds like you may have an allergy to cashews.
Thank you. I was hoping it was some weird exotic reason such as chemicals used in processing or a mad fairy godmother. (LOL.)
Cashews are odd; the part we consume (the seed, not really a nut) is only part of the fruit. In order to be safe for consumption, the seed must be freed of naturally-occurring urushiol, the same compound that makes poison ivy such a toxic nasty. Although roasting supposedly destroys all of the urushiol, I sometimes wonder if people that have an extreme sensitivity to urushiol might respond to some tiny vestage of the stuff.
Or, more likely, you’re simply allergic to cashews.
Thanks for that well reasoned argument, thoroughly backed with an invitation to Google for something which turns up an Asian advert revenue generation farm. Do please add more of your insights when they occur to you. That certainly told Mark Sisson what’s what.
Hi there,
Thanks so much for this post. I have been wandering around the web trying to figure out some remaining skin issues for my 3 year old daughter’s and I feel like this may be the last diet issue we need to contend with.
We have been eating a paleo diet for just over a year now. We noticed with my daughter that after cutting out grains and in particular, dairy, her skin (face, back of arms) really cleared up initially (as did mine). But in our early days of paleo, we were cooking/baking a lot of substitutes (pancakes, breads, muffins, cookies, some seriously yummy stuff that helped with the transition) but in recent months we have cut back to the basics – meat, veg, some fruit, and nuts. Over time the backs of her arms and cheeks really flared up again. We thought it might be an issue of consuming too much fruit (she is MAD about fruit, in a serious way) but realize that her nut consumption is also really rather high. She is a small person and eats loads of almonds, almond butter, pistachios, walnuts, etc. There was a time she was consuming a bowl every morning at 5am – kept her quiet until 6 or so.
I have realized that my skin issues (back of my arms particularly) have cleared as I eliminated nuts – they just dont make me feel 100% and I rarely feel like snacking anymore so they are easy to get rid of.
I wonder if this could be the issue for her. We have taken her off nuts for a four or five days now (and she cries for them daily like I have seen other kids cry for candy or goldfish crackers) so we will see if her skin begins to heal in time.
Have you heard of anything like this before? I would love to know if anyone else has experienced this or if I should be looking elsewhere in her diet? I dont want to make her kooky with food issues but I also know she is a sensitive little gal and would like to get things in order for her so she doesn’t have to deal with skin, digestive and other issues like my husband and I.
Thanks!
Does chestnut contain phytic acid? thanks!
Hi, Chris!
I listened to your podcast the other day which led me to this post. I am glad you wrote it — it’s a very important post. Just because we avoid grains does not mean we are avoiding phytic acid, especially if we are eating lots of unsoaked nuts, seeds, and chocolate.
Regarding coconut flour, there is a letter from Bruce Fife, ND in the new fall edition of the Weston A Price Foundation’s Wise Traditions journal.
According to Bruce, we do not need to soak coconut flour. I posted about it today, with the quote from Bruce:
http://www.cheeseslave.com/2011/11/02/should-we-soak-coconut-flour/
It makes sense to me. The coconut flour is made from the meat of the coconut, which is also what the coconut milk comes from. He makes the point that the coconut meat is naturally soaked in the coconut water (in the shell) for about a year. He also makes the point that many traditional cultures lived on coconut as a staple and they didn’t show signs of mineral deficiencies.
Ann Marie
Hi Ann Marie,
Bruce commented earlier in this thread, and yes, and I did read his letter in the WAPF journal. I agree that makes sense. Thanks for your comment.
Oh good!
Well, no wonder I didn’t see it. There are like 10,000 comments on this post! You definitely struck a nerve.
The Blue Zone research is that eating 2 ounces of nuts 4-5 times per week increases longevity. (http://www.npr.org/templates/story/story.php?storyId=91285403).
I wonder if this is due to the high phytic acid in the nuts reducing serum ferritin levels? For this to be the case, best would be to eat the nuts as a snack, at least 2 hours before/after a meal. Any phytic acid that doesn’t bind to minerals in the gut is absorbed into the bloodstream, where it can bind to iron (and other minerals). But this effect from nuts could easily explain why they increase longevity.
Yes, Tim,
Many other sources on longevity, as well as the one Chris quotes from here, don’t paint such a negative picture of nuts as seems to have turned up here (“Food Phytates”). I really can’t see how nuts, which are usually eaten as a snack, either to the exclusion of other foods, or combined with few foods, and definitely not eaten with a meal, can have much of an effect on all the rest of the food eaten during, say, 3 or 4 meals of one’s daily life. Most healthy people on a primal diet have rapid elimination, and there is little “co-digestion” of meals in the intestine. Therefore, a snack of nuts, and the contained phytates, will have little effect it would seem, on all the minerals that have been provided by foods in the other daily meals. And if one eats an entire meal of nuts, but does so only every other day, it has even less effect on the total mineral intake of an individual.
Personally, I eat nuts whenever I want, and have for years. And I eat what might provide 3 or 4 times the amount of phytic acid that is indicated as healthy in this article, as I usually eat almonds by the handful. The good part about my diet though, is that I hardly ever eat legumes or grains, and I almost always have the large quantity of nuts as an evening snack. So my typical meal is devoid of any significant amount of phytic acid. That is probably what allows me to have normal levels of mineral when I have had a hair analysis. Because of the actual test on my actual body, I tend to take advice such as that in this article more as sensationalism than as advice to start guiding my life by. I need a “sample size” no great than one to determine what is working for my body: I eat nuts, my minerals are plentiful.
However, I’m not saying that I think I would be just as healthy with regard to minerals on board if I were eating a diet of grains and beans daily. I’m just happy I got off that habit quite a while ago, and have felt better ever since.
Thanks for providing the link to the “Blue Zone” review. That’s a book I still need to read!