Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
16 May

Nuts and Phytic Acid: Should You Be Concerned?

Who doesn’t like nuts? They’re crunchy, fatty, nutritious, and convenient. They travel well. Tossing them into the air and catching them with your mouth is a fun way to impress any onlookers (this effect is enhanced if you sit in a chair backward at the same time). They even turn into butter. Nuts are the common bond between all dietary sects, it seems. Vegans love them for the protein. Ancestral eaters accept them, some begrudgingly. Weston A. Pricers have to soak, sprout, dehydrate, and ferment them before they’ll even consider eating nuts, but in the end, they love them. Mainstream healthy dieters dig their “healthy fats.” Epidemiologists, squirrels, and birds laud them. They’re self-contained little morsels of instant edibility, good raw and roasted alike. What’s not to like?

Well, there’s the phytic acid. Wait – isn’t that the stuff you find in grains and legumes? Yes. Should we be concerned? Let’s take a look…

Hi Mark,

I was hoping to get your take on phytic acid in nuts. If nuts are so good for us, and beans and grains so bad, but all three contain a good amount of phytic acid, what’s the deal?

I like nuts. I guess what I’m really asking is: can I still eat them?

Thanks,

Cindy

Yes, it’s true. Nuts contain a lot of phytic acid, AKA phytate, AKA IP-6, AKA the storage form of a plant’s phosphorus, and antioxidant to the seed in times of oxidative stress (PDF). When something that contains it is eaten, phytic acid binds to minerals like zinc, iron, magnesium, calcium, chromium, and manganese in the gastrointestinal tract, unless it’s reduced or nullified by soaking, sprouting, and/or fermentation. Bound minerals generally cannot be absorbed in the intestine, and too many bound minerals can lead to mineral deficiencies. Animals who produce phytase – the enzyme that breaks down phytate – can thrive on phytate-rich foods. Rats, for example, produce ample amounts of phytase and can handle more dietary phytate without exhibiting signs of mineral deficiencies. Since humans produce around 30 times less phytase than rats, phytate-heavy diets might be problematic for humans.

By dry weight, nuts generally contain more phytic acid than similar amounts of grains and legumes. If you don’t believe me, take a look at this table, pulled from Chris Kresser’s excellent article on phytic acid in nuts:

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

So, 100 grams of almonds has between 1138 and 1400 mg of phytic acid. Walnuts have 982 mg, and 100 grams of Brazil nuts tops the list with over 1700 mg!

Meanwhile, 100 grams of brown rice has between 840 and 990 mg, lentils have 779 mg per 100 grams, and oats contain just over 1100 milligrams.

So what’s the deal? Why do nuts get a pass, while grains and legumes get condemned?

First of all, grains and legumes are generally seen as dietary staples. They form the foundation of meals. People don’t have a “small handful” of refried pinto beans (and not just because that’s an incredibly messy way to eat them) or “one or two” grains of brown rice. They eat plates of this stuff, they rely on them for protein and calories, and sure enough, cultures whose diets are based on (improperly prepared) grains and legumes often suffer the symptoms of widespread mineral deficiencies, like nutritional rickets.

Nuts, on the other hand, are an adornment to a meal or a snack in between. A condiment. They are not meals themselves. And though I hear stories of people going Primal and subsequently going crazy with nuts, eating almond flour bread with every meal and downing a pound of pecans each day, I just don’t see it. I could be mistaken, of course. If I am wrong, and you guys are indeed eating large quantities of phytate-rich nuts every day, don’t do that. Keep it to about a handful (which is between one and two ounces, depending on the hand) per day. But my general sense is that people aren’t eating copious amounts of nuts. They’re eating some nuts in between meals, on those days when they just need a snack. They’re making almond meal pancakes once or twice a month (cause let’s face it – they’re kind of a drag to make and clean up after).

It’s quite telling that all the studies looking at the effect of phytate on mineral bioavailability focus on grains and legumes, not nuts, because grains and legumes are what people are actually eating and relying on for nutrients. In 2007, the average American ate 610 grain calories and just 89 nut calories per day. I strongly suspect those numbers would look a little different for a Primal eater, but my point stands: you don’t see any studies examining the effect of almond intake on mineral bioavailability because nobody’s relying on almonds for their nutrition.

Second, those figures are for “phytate per 100 grams dry weight.” 100 grams of almonds is a little different than 100 grams of brown rice in the real world, on your plate, and in your mouth. The brown rice is about 362 calories, while the almonds are 575 calories. You’re far more likely to plop 362 calories of brown rice onto a plate and go back for seconds than you are to eat almost an entire cup of almonds in a sitting. 100 grams of rice is a standard meal; 100 grams of almonds is veering out of “snack” and into “meal” territory.

Is there an “ideal” way to eat nuts with respect to the phytic acid content?

Although asking “What would Grok do?” doesn’t give us definitive prescriptions for what we ought to do, it can be a helpful starting point. How would our ancestors have eaten nuts? By the plastic shrinkwrapped pre-shelled and salted bagful? Or by the laboriously gathered and hand-shelled occasional handful? Eating nuts is effortless now, but it wasn’t always like that. Ever crack a macadamia shell by hand? A Brazil nut? An almond? It’s hard work. You’re either trying to break open a rock-hard shell or sifting through fragments of shell and nut to find something edible. If you eat your nuts like you had to gather and shell them yourself – rather than gorging on them by the handful – you won’t be able to consume a significant amount of phytic acid.

If you’re still worried about phytic acid from nuts, you can play around with food timing. In order for phytate to impair absorption, it has to physically come into contact with the minerals in question. Since mineral absorption – or non-absorption caused by phytate chelation – happens in the gastrointestinal tract, that wild and crazy place where masticated and partially digested food particles gather, mingle, and sometimes pair up, keeping the food in your gut away from the phytic acid in your gut by eating the nuts separate from other foods might improve your mineral status. The minerals in the foods with the phytic acid will presumably be affected, but the impact on other sources of minerals should be reduced. Eat your nuts apart from other sources of minerals. Sorry, those Brazil nut-crusted oysters, while delicious, might be a bad idea for zinc absorption.

This is in stark contrast to the way most people eat their phytate. The average person out for Mexican food, who eats grains and legumes with relish, is having four corn tortillas (448 mg phytate) with a small scoop of refried beans (622 mg) and some brown rice to, ya know, be healthy (990 mg). He throws in a few hefty slices of carne asada, but the combined 2060 milligrams of phytic acid for that meal will impact its overall mineral contribution.

The average Primal person, who avoids grains and legumes, has an ounce, or a small handful of almonds as an afternoon snack (350 mg phytate) with a couple Brazil nuts (171 mg) for the selenium. Being snacks, they’re separate from his meals. Being separate from his meals, the antinutrient effect of the phytate on the other minerals is lessened. If he bumped that up to 100 grams of each nut for over 3000 mg of phytate and over 1200 calories, then, yeah, he’d have a phytate problem (and an omega-6 problem). But he’s not doing that.

Unless you’re a Hadza, you shouldn’t be relying on nuts for the bulk of your nutrients and calories. And that’s the important thing: you don’t have to, nor are you compelled to, because the Primal eating plan is an overall nutritious one, full of mineral-rich vegetation, animals, and yes, the occasional handful of nuts. You’re not relying on plant foods for your zinc – you’re eating shellfish and beef and lamb for the far-more-bioavailable animal-based zinc. According to the evidence I was able to find, phytic acid simply isn’t a major concern in the context of a nutritious diet, especially one that contains ample amounts of  animal-based minerals and protein.

Besides, you wouldn’t want to completely eliminate phytate from your diet, even if it were possible. There are a number of possible beneficial health effects of a moderate amount of phytic acid which I’d be remiss if I didn’t mention, like:

So to answer your final question, yes, I’d say you can definitely eat and enjoy nuts in moderation, an ounce or two (especially soaked) as long as you’re eating an otherwise nutrient-dense diet.

Which you are, right?

Thanks for reading, everyone. Be sure to leave your thoughts in the comment section.

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Well this was a good article for me to read. I have suffered from low iron (before going gluten free), and I always find info like this really interesting. I have a bit/massive weaknesses for almond butter (used to be peanut) so I try not to buy it as ill eat it in a week! This info will make me think twice! What about coconut flour?

    Victoria wrote on May 17th, 2012
  2. I eat a handfull of nuts every meal. Around 9 to 15 nuts each meal which makes almost a kilo in a week. Would that be to much then?

    Jack wrote on May 17th, 2012
  3. I think we are all massively over thinking this subject. Grok would not have even considered any of the potential health risks be they big or small. He would have thought ‘FOOD’ end of story. Rather than would Grok have eaten this we should more along the lines of HOW would Grok have eaten this. Certainly with the best will in the world I cannot imagine him turning to his family first thing and saying “Does anyone fancy almond pancakes for breakfast?” As a few here have mentioned , Groks family as hunter gatherers would come across nuts occasionally and enjoyed them when they did. If we copy this kind of intake then I don’t see we can go very wrong..

    steve wrote on May 17th, 2012
    • Damn, there goes that delicious cream, port and onion sauce my husband made for last night’s liver.

      Orielwen wrote on May 17th, 2012
    • The question is, how often is occasionally? Once a day, once a month, once a year? Vastly different results.

      Sofie wrote on May 20th, 2012
  4. I use nuts for breakfast (as a topping over my banana and apple honey meal). Is that a bad combination?

    What Mark is saying is that you don’t have to overdue it, but I’m not sure which combinations are not wise.

    Sascha wrote on May 17th, 2012
  5. Ah, but they DO eat multiple handfuls of nuts. Try as I might to put a few grains of something into a recipe, I get yelled at for not being “primal” and trying to poison her…but she’s perfectly fine eating half a jar of nuts!

    Andy wrote on May 17th, 2012
  6. Raw nuts that have been soaked and dried in a dehydrator (no higher than 115 degrees) are amazing. This process neutralizes the enzyme inhibitors naturally found in nuts. You’ll notice the difference right away. And yes, they are a snack not full meals.

    Tara wrote on May 17th, 2012
  7. I literally don’t eat too many nuts because it annoys me that bits always get stuck in my teeth and I have to spend a minute rinsing out my mouth of nut bits. Other than that, I love saltless, shelled sunflower and pumpkin seeds :) and almonds.

    Christina wrote on May 17th, 2012
  8. On or off paleo I have a heck of a time with nuts, faux and otherwise. They seem to trigger awful hand eczema (dyshidrosis). It started with peanuts, even a small amount, and now includes more than a handful of any true tree nut. Allergy tests are negative so I’m down to either chromium/nickel imbalance (per pubmed) or some near-identical protein thing I haven’t found any real science for. So, seeds only for me.

    Anne wrote on May 17th, 2012
  9. I was eating about 1 cup of almonds everyday as a staple. It took a while to figure it out, but my scalp begin to develop small scabs. I stopped eating the almonds and the scalp thing cleared up. If I start to eat almonds again, it comes back.

    I attributed the problem to the high omega 6 content. Now, having read about phytic acid, it seems more likely that it was the cause. In any case, I am an example of what happens when one makes almonds a staple.

    nick wrote on May 17th, 2012
  10. Buy nuts AND SEEDS correctly presoaked and dried on the web. Wilderness Family Naturals is one source. Other companies may have them but mix them in their product line with nuts and seeds NOT soaked and dried so read carefully. Nourishing Traditions Book has 5 pages on different nut and seed soaking recipes that makes the cost of the whole book worthwhile. Rosemary, butter, etc. for roasting AFTER the soaking and drying.

    beverly wrote on May 17th, 2012
  11. For almonds, does a significant amount of the phytic acid reside in the skin? I buy blanched almonds because I seem to digest them better.

    Primal Toad wrote on May 17th, 2012
  12. I love nuts. I buy the Trader Joe’s Go Raw Trek mix. What about the raisins? I also add dried cranberries. What about those?

    Kaiser wrote on May 17th, 2012
  13. I love nuts! All kinds. I buy the Trader Joe’s Go Raw Trek Mix. What about the raisins in it? I also add dried cranberries to it. What about those?

    Kaiser wrote on May 17th, 2012
  14. Great article – thanks Mark.

    Natasha wrote on May 17th, 2012
  15. I don’t eat a lot of nuts on their own, but when I first started PB I was baking every week with almond flour because wanted to compensate for missing bread and sweets. I now bake about once a month, because every time I bake I also way overeat, which not only causes digestive issues but makes me feel like crap in general.

    Mary wrote on May 17th, 2012
  16. I drink 300ml of almond milk a day is that too much???

    jeannie wrote on May 17th, 2012
  17. Is phytic acid carried over completely into the processed forms of nuts, such as, say, almond milk? Or is much of it lost in the process?

    GrokCard wrote on May 18th, 2012
  18. Mark–Good article. But doesn’t your chart list grains and legumes by dry weight? Dry weight of 100 grams is quite different than a cooked 100 gram serving. Oatmeal is the only dry grain listed in the latest Bowes and Church (food comp tables) 1 cup dry oats weighs 87 grams, 1 cup cooked weighs 234 grams.

    Jan wrote on May 18th, 2012
  19. Any data on macademia nuts?
    How about eating 85% or 90% cocoa chocolate after a meal?

    Jerry wrote on May 18th, 2012
  20. The more pertinent question is not whether it’s primal to eat nuts but whether it’s nuts to eat primal.

    jeffersonianideal wrote on May 18th, 2012
  21. hi
    i use amaranth flour and arrowroot flour to make chapatis everyday..and add a little flax seed meal to it…is it healthy enough to be eaten everyday?

    alefiya wrote on May 19th, 2012
  22. I’ve clued in to the fact that many of the nuts in the bulk aisle are contaminated with gluten so that’s a factor.

    catrina wrote on May 19th, 2012
  23. Hi, I came across this article because a recent blood test showed up a bit too much iron in my blood, and I’ve googled it and started learning about hemachromatosis.

    Have I got this right? In order to reduce my absorption of iron, I can go ahead and eat more nuts? Yes?

    Jean wrote on May 20th, 2012
  24. Have been happily chomping on nuts as a snack to stave off hunger pangs during the (long) working day. As a Brit I can walk into any High Street and get raw nuts in several supermarkets and stores, more options than you can shake a stick at. Finding myself in Chicago for a couple of days I cannot find a nut on the Magnificent Mile (where my billet is) that hasnt been roasted and salted. Where do I get raw nuts from ?

    Amaethon wrote on May 20th, 2012
  25. I love nuts, I generally sprout them first though by soaking them in water overnight for almonds. Or at least a few hours for other nuts. They are great, nutrient dense, amazing snacks!

    Jia Ni wrote on May 20th, 2012
  26. Good idea. I love soaking my nuts!

    herman johanson wrote on May 20th, 2012
    • tee hee

      zippitydoda wrote on May 23rd, 2012
  27. Very interesting information and very helpful. Good to know that a “moderate” amount is about a hand-full and the phytate information – along with the comparison with other phytate-rich foods – is very useful info.

    Thanks for the great blog posts and all the great information provided.

    chrialivest wrote on May 21st, 2012
  28. A very interesting post, Mark. Thanks.

    OnTheRun wrote on May 22nd, 2012
  29. Just a small point – the San (Ju/’hoansi) eat a lot of nuts (Mongongo), the Hadza eat effectively no nuts. The Hadza also have higher bodyweight and appear stronger and healthier to my eyes. The San are the thinnest of the extant HG groups.

    Richad wrote on May 23rd, 2012

Leave a Reply

If you'd like to add an avatar to all of your comments click here!

© 2016 Mark's Daily Apple

Subscribe to the Newsletter and Get a Free Copy
of Mark Sisson's Fitness eBook and more!