Another Reason You Shouldn't Go Nuts on Nuts | Chris Kresser

Another Reason You Shouldn’t Go Nuts on Nuts

by Chris Kresser

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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.

Phytic acid interferes with enzymes we need to digest our food, including pepsin, which is needed for the breakdown of proteins in the stomach, and amylase, which is required for the breakdown of starch. Phytic acid also inhibits the enzyme trypsin, which is needed for protein digestion in the small intestine.

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.

If you’re on a Paleo diet you’re already avoiding some of the higher sources of phytic acid: grains and legumes like soy. But if you’re eating a lot of nuts and seeds – which a lot of Paleo folks do – you still might be exceeding the safe amount of phytic acid.

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 nuts1719
Cocoa powder1684-1796
Oat flakes1174
Almond1138 – 1400
Walnut982
Peanut roasted952
Brown rice840-990
Peanut ungerminated821
Lentils779
Peanut germinated610
Hazelnuts648 – 1000
Wild rice flour634 – 752.5
Yam meal637
Refried beans622
Corn tortillas448
Coconut357
Corn367
Entire coconut meat270
White flour258
White flour tortillas123
Polished rice11.5 – 66
Strawberries12

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.

Modern evidence also suggests that at least some of the phytate can be broken down by soaking and roasting. The majority of this data indicates that soaking nuts for eighteen hours, dehydrating at very low temperatures (either in a food dehydrator or a low temperature oven), and then roasting or cooking the nuts would likely eliminate a large portion of the phytic acid.

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.

460 Comments

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  1. Yes! Thank you! I finally figured out that raw nuts make me constipated. So do beans as well as raw veggies with lots of insoluble fiber aka roughage.

    This article is probably why. So maybe I can eat the rest of the nuts I have and not be miserable if I soak and roast them.

  2. Again Chris is misinforming the public. soaked and sprouted nuts are extremely healthy and easier to digest

  3. I like to consume chia seeds because of their fiber (would like to move toward a paleo fiber consumption). Is there a way to soak chia seeds then let them dry out in a dehydrator before grinding and hydrating to drink? How sensitive are the oils in the seeds to low heat drying?

    Just curious if you knew anyone that had tried this approach.

  4. “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.”

    This confuses me because grains are the basis of long lived civilizations. The blue zones don’t seem to reflect your comments. What societies eating beans and whole grains, or I guess plant based diets for the most part have rickets and osteoporosis?

    • I think it’s a mistake to eliminate such large food groups like grains, nuts, legumes, etc. Why not opt for moderation? If you read as many health-related articles as I do, pretty soon there won’t be much of anything left to eat. It’s good to be aware of the downside to certain foods, so you don’t over consume them.

  5. Question: I’ve recently realised personal digestive issues due to normal plain ‘milk’ chocolate that I have been eating just after dinner. Presumably the phytic acid within the chocolate knocks all the nutrients out of this main meal and also leaves undigested food as problematic in the intestines (fuel for bad bacteria). These negative digestive and health issues last for at least three days after consumption.

    I recently tried 70% cocoa chocolate and only had a couple of portions (2 x 25 grams) just after dinner. Same issue with the negative symptoms lasting a few days.

    Question: would 85% cocoa be better or worse? I assume the more cocoa, the more phytic acid. Additionally, does it then also need to be consumed a couple of hours away from a meal (so that the phytates don’t interfere with the nutrients in that meal)?

    Thanks in advance,
    Barry (ready to give up chocolate completely)

  6. According to the latest research , this article regarding negatives of phytates is in error. Type in phytates at the non commercial site NutritianFacfs.com with Dr. Micheal Gregor and his 14 researchers for detail explaination of how body recycles phytates because of phytates benifits

  7. As my mother used to tell me ‘moderation in all things’ and that includes nuts.I doubt there is one single thing we ingest which does not have something harmfull in it (save water) but perhaps the deadliest sin,gluttony(with sloth following close behind) is the one we should watch out for.If it’s more than will fit in your hand it’s too much.

    • exactly…..what the heck is left to eat…..I fill up on nuts replacing carbs…but the lectin in nuts will mess me up?……

  8. GIVE ME A BREAK .. OK, so lets break it down
    Meat based diets are “proven” to be bad
    Green veggies need to be cooked or they are “Bad”
    Nut and seeds are “BAD”
    ……………………………. everything we eat is bad … I guess we can’t eat at all .. Next article title will be
    ~ALL FOOD KILLS, SO STOP EATING AND STARVE~

    • Wow, I feel the same way — the more I read, the more things I can’t eat — it’s so confusing. I need a nutritional biology degree, and even that probably won’t tell me everything that I need to know.

  9. Valuable analysis ! I loved the details , Does anyone know if my business could locate a fillable Freddie Mac / Fannie Mae 710 form to complete ?

  10. WOW ONE of the worst advice ever! Please do not cook your nuts, just don’t do it. Polyunsaturates are very prone to oxidation! When these fats react with oxygen during heat cooking they form toxic byproducts and go rancid. You may end up with oxidized LDL which is bad for your arteries! Please if you really like nuts just eat them was/naturally.

    • just eat the raw phytic acid eh, good advice, research tradition, they didnt just ferment boil cook soak roast etc for fun, nor did they listen to some greedy hillbilly

      • I’ve been reading this blog for quite a while, and you are the first person to use name calling in your reply. Shame on you.

  11. This is irresponsible fragmented thinking. When is every so called “expert” going to realize that making claims like IP-6 aka “phytate” is bad or good? Is it more likely it has numerous benefits and also likely some drawbacks?

    I own a genetic testing company, and can empirically prove, that this one size fits all mentality is dangerous, and irresponsible.

    I respect the free exchange of ideas, but, this is fear mongering plain and simple.

    When ANYONE can prove they have the answer for everyone, the, and only then, can they speak other than based on fragmented thinking.

    People, WAKE UP!!!

    • Thanks, Jeff. It’s good to hear from a qualified professional!

      linkedin [dot] com/in/jeffrey-gilison-39232057

      CEO
      Jenetics, LLC
      January 2013 – Present (3 years 2 months)
      Offers a key to personalized health: Genetic (DNA) testing that helps patients, doctors, and nutritionists to determine the right path based on known clinical genetic factors offering patients truly personalized medicine. We have over 6 new proprietary tests and many more coming to the market. We take pride in innovation and thinking outside the box to solve issues.

      We know that the one size fits all approach to health is absurd and proven to be dangerous. This business has been founded based on my own personal health journey. My goal is to achieve better health through actionable information!!! Affordability, convenience, and clear reporting is essential to effective use of genetic information and testing.

      COO, Sales Manager
      Keepers Unlimited, Inc
      January 1997 – Present (19 years 2 months)
      Active wholesaler of unique high end sports memorabilia to the largest auction houses, trading card companies, and other niche markets.

      Sales Manager
      Mobile Homes Central
      January 2001 – January 2004 (3 years 1 month)
      With this company I had some unique opportunities to help individuals correct their past credit issues and also worked in conjunction with both banks as well as direct private lenders to help put mutually beneficial deals together between the lenders and the consumer. I had a sales force of 20 plus other individuals that I supervised as well as being involved with the executive issues and decisions that were made.

      Sales Manager /CEO
      Wholesale/Manufacturing – Gilison Knitwear, Inc
      January 1993 – January 2001 (8 years 1 month)
      then VP, and for the 3 final years I became President of the company. Here I learned to handle the marketing, sales, and production for a triple A Dunn & Bradstreet rated company. The company had over 100 employees and over a dozen sales reps whom all eventually were directed by me. I gained invaluable experience in so many facets including sales to every major retailer around the globe including Walmart, Target, Kmart, Sears, Saks Inc., Federated Stores (Macy’s), as well as making private label goods for Major Brands such as Philips Van Heusen ( Izod, Arrow, Calvin Klein, Van Heusen, and others) , Tommy Hilfiger, and dozens of other large brand names. I became proficient at micro-managing, target marketing, product development from concept right thru to production ( QC-quality control, EDI-electronic data invoicing, raw materials purchasing, customs, controlling overseas production utilizing an agent primarily importing from China). Domestic production was handled in the Long Island factory and we also had a midtown sales showroom in Manhattan.

    • Yes now the genetic analysis companies are getting in on the fear mongering as well….. “get tested or else you are not sure of how to nourish ourselves. Just a different angle, and marketing to build a profit. Don’t let yourself get too high and mighty

    • just eat the raw phytic acid eh, good advice, research tradition, they didnt just ferment boil cook soak roast etc for fun, nor did they listen to some greedy hillbilly

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