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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What about this?
“Emerging scientific evidences reveal that phytic acid has several positive effects on human health.”
http://www.tandfonline.com/doi/abs/10.1080/03670244.2011.604588
You can’t get antioxidants from something that won’t deprive you of minerals? People in Kenya who eat seed foods are not exactly the picture of perfect health. If all they ate were the seed foods they’d be even worse off. I really think these “high carb” traditional cultures only get away with the high carb because they eat other foods that protect them. We are losing that protection in industrial countries thanks to heavy emphasis on avoiding animal foods.
“We are losing that protection in industrial countries thanks to heavy emphasis on avoiding animal foods.”
My crack dealer called and was wondering who’s your supplier?
Hi Chris, Can you provide any information on phytase levels in nuts/coconut/cocoa, if any? I understand that phytase breaks down phytates into bioavailable phosphorus. Also, most cocoa is fermented in the ground (not sure about raw). Even Cadbury’s chocolate is harvested and processed this way: http://www.cadbury.com.au/About-Chocolate/Harvesting-and-Processing-Cocoa-Beans.aspx.
Thanks for the article. I frequent your site, and your info has changed my life!
Marissa
gutreal.blogspot.com
A freakin men. I’m sick of reciting this to those who avoid things like rice but face pack nut products.
How about almond milk?
thanks
Commercia almond milk often has quite a bit of sugar and carageenan. Carageenan has been linked with intestinal cancer and causes gut distress for susceptible people. Homemade almond milk is probably relatively low in phytates, but I haven’t seen numbers.
Chris Have you read Dr Steven Gundry’s take on phytates and why they can be helpful to adults (not pregnant or severely ill)? He contends that a little of what is bad can be good.
Drs M & M Eades argue that older adults can benefit from a lower iron load. Perhaps phytates can help with this rather than going down the blood transfusion route that they recommend.
Other ‘healthy’ elements of the diet also bind to minerals, particularly iron, such as oxalic acid found in spinach and chard.
Nina
Yes, there is some evidence that phytates can be beneficial in certain circumstances. I recently read an animal study where they showed that phytates reduced the symptoms of Alzheimer’s. That’s why I don’t think it’s necessary or even helpful to avoid all phytic acid – just to minimize it.
Hi Chris,
Do you happen to know if there are anti-nutrients like phytic acid in seeds like those from fennel, cumin?
Cheers
Michael
I’m not sure, but unless you’re eating a huge amount of them it would be minimal overall impact.
Thank you for the link discussing polyphenols, an interesting read.
Are any nuts commercially available that have been prepared so as to reduce the phytic acid level? This preparation would probably push them into the definition of a “processed” food, but perhaps in a good way?
My 6 year old son has reflux (doesn’t bother him but he often regurgitates his food) and does consume lots of nuts and I’ve made muffins pancakes and such with coconut flour. A line you wrote about the phytic acid interfering with protein digestion struck me as a possible ah ha. Thoughts? We have done food sensitivity tests, digestive enzymes and are going to try a stool sample. He is gluten and dairy free. Thanks for all the work you do.
Nut and particularly coconut flour are very high in insoluble fiber, which is indigestible and can cause gut problems in certain people. That – more than the phytic acid – would be my guess in your son’s case. Try a diet low in insoluble fiber and see if that helps.
Iara,
I was a chronic reflux sufferer as a child which I lived with well into my adult life. I had an endoscopy and was advised that major surgery was the only option. Suffice to say, I declined. Ultimately, I visited a Naturopath friend of mine who fixed it within 24 hours. Yes 24 hours! and this was after years of constant suffering. I was previously taking drugs for reducing acid production and drugs reducing acid time in body (until I read reports of the said drugs causing death).
Obviously I only have my personal experience and the limited information in your comments but for me it was a simple as eating ‘good food’. Completely eliminate Fast Foods, sugary treats, and processed or chemically altered food. For me, I found banana (my favorite fruit), bread (any type), and fast food in general would cause reflux (alcohol is also bad but probably not an issue at the moment for your son!). Since ‘living healthy’, I suffer ZERO reflux and only ever feel anything if I have indulged in the forbidden food.
I am now Paleo and find it to be, without a doubt’ the best option. Don’t get bogged down in the detail – for every good food you think you have found you will find something wrong with it. Hence the amount of responses to CK’s article. Although he has stated several times that nuts are ok in moderation, this site is still bombarded with ‘nuts no more’ comments.
My simple view is this – Eat any food that is natural, avoid processed foods or any foods that are altered (i.e if you want to drink milk, drink it full fat). A basic diet of meat, fruit and vegetables will be able to keep even a six year satisfied (a bowl of fruit salad with some full fat cream or even quality icecream – c’mon!!). And as long as everything you eat is IN MODERATION, you should not expect to have any issues
I hope this helps as I would not wish reflux on anyone – certainly not a six year old.
Cocoa powder is widely touted for its polyphenol content . Are we now to be concerned that the risk of phytic acid outweighs the polyphenol benefits?
I understand about moderation – in the same way that I limit my consumption of fruit (fructose!)
Doesn’t all of this just go back to common sense..i.e. – all things (or most all things) are ok, in moderation?
I gotta say it. I do lots of reading about nutrition. There is apparently only one food item, and one only that appears to escape debate – leafy greens, in moderation of course 😉
The health benefits of polyphenols are also subject to moderation: http://wholehealthsource.blogspot.com/2011/02/polyphenols-hormesis-and-disease-part.html
Yes, it goes back to common sense. But certain things (like the need to soak/prepare nuts and seeds before eating them) aren’t always obvious.
There is an interesting article on phytates in the Journal of Nutrition at the following address;http://jn.nutrition.org/content/133/9/2973S.long, titled:Influence of Vegetable Protein Sources on Trace Element and Mineral Bioavailability. It advises that phytase from buckwheat or rye, at appropriate ph can eliminate phytates used at 10% of total. Interesting that phytates in beans occur in the cotyledons not merely skin.
Chris,
what are your thoughts on pure cocoa butter, is it safe to eat for people with digestion problems?
Chris,
A very interesting post! As a consumer of nuts, I am concerned about phytic acid. I was unaware of how much is in my favorite nut, almonds. Thank you for the information. Preparing nuts properly (soaking/roasting) as you and WPF suggest can damper the effects of phytic acid. Is it possible, however, that roasting nuts could be adding another problem by heat damaging the fragile, polyunsaturated fats in the nuts?
“6700 BC, Colonsay (UK) A midden pit containing hundreds of thousands of charred hazelnut shells, all harvested in the same year, on a raised beach at Staosnaig.”
After the ‘paleolithic’ period, though!
I’d still like to see detailed information regarding chocolate and coconut products, especially cocoa powder, dark chocolate bars, coconut milk and coconut meat, thanks.
Is there a hormetic effect from consuming moderate quantities of phytic acid?
I’d like to second dada’s question above. If I understand correctly from the comments, coconut oil is fine as levels are low enough. The list up top includes “coconut” and “entire coconut meat” separately, which is somewhat confusing. I’m wondering if coconut milk should be avoided or consumed in limited quantities (and/or how this relates to cultures who consumed/consume a ton of coconut).
Many thanks for the informative article! I’ve been wondering about nut consumption and many new paleo/primal eater’s almond butter habits (including my own).
Folks, as I said in the article it’s not necessary to eliminate phytic acid completely. We can tolerate a few hundred milligrams of it without a problem. My understanding is that the bulk of the phytic acid is in the bran or hull of the grain, seed or nut, so I doubt coconut milk or oil has significant amounts.
So if the bulk is in the bran or hull, would nuts with the outer cover removed (blanched?) be better?
Similar question about the coconut – if I removed the thin edible brown outer cover, is the white part safer to eat?
Chris, what’s the best type of chocolat/cocoa powder? Dutch process or not? Does the Dutch processing, whatever that is, remove some of the phytic acid? Any brand recommendations? I have to make chocolate ice cream (low in sugar) from time to time for peace at home and mental health. Thanks!
Again, if it’s an occasional treat I don’t think it matters much.
Hi Chris. Thank you for the very informative post. I have been looking for the answers to the exact same questions asked above. Does the Dutch process reduce phytic acid? I have been searching online for hours and I still cannot find any solid information on the topic. I have problems absorbing iron (I am Vegetarian) and although I only have cocoa powder occasionally I would still like to know if Dutch cocoa powder would be a safer option as I am trying to reduce my phytic acid intake as much as possible (even with foods that are a ‘treat’). Thank you 🙂
I too would love to hear the answer about macadamia nuts!? I read in an earlier post of yours that they are the ‘best’ nuts to eat due to the omega 6 to omega 3 ratio. If I do snack on nuts on the odd occasion, they are the ones I eat. Thanks for the great information as always Chris!
I haven’t been able to find info on phytic acid content of macadamias, but if you’re only snacking on nuts on the odd occasion, as you said, you could choose any nut and it wouldn’t matter. We’re capable of dealing with some phytic acid.
Will continue to use them on the odd occasion as I have been doing then. Thanks heaps for your reply Chris, greatly appreciated.
i recently started eating about 100gr of cashew nuts a day ,i m a bit concerned now
What about macadamia nuts? They are the lowest by far in omega 6: 1.3grams per 100 g of nuts and cashews, 7.8g per 100g, compared to almonds 12g omega 6 per 100 grams of nuts. (http://paleozonenutrition.wordpress.com/2011/05/10/omega-6-and-3-in-nuts-oils-meat-and-fish-tools-to-get-it-right/)
Do they have much phytic acid?
I heard Mat Lalonde say the best nuts were those with hard shells like macadamia because the shell is their defence against digestion, rather than anti-nutrients.
Almonds & walnusts have hard shells too though… I see the logic there, Julianne, but I wonder then why they come out atop the list. Hmm…
Not sure if this has anything to do with it, but macadamia nuts and cashews seem to be different than other nuts in terms of lack of that outer brown, papery, fibrous layer (the bran maybe?). Maybe that is where majority of the phytic acid is in the other nuts?
I’ve read before and it made sense to me that a good amount of the phytic acid is in the skin of the nut or seed. So, blanched almonds are a lot better than not blanched almonds. My tummy is not a fan of raw almonds with the skin but can handle blanched almonds a lot better!
I believe there may have been a decimal point error.
According to the book you linked: “Food Phytates” (N. Rukma Reddy, Shridhar K. Sathe), brown rice would have 840-990 mg (p.30) and for parboiled brown rice 1600 mg (p.32).
Why does parboiled brown rice contain more, especially when calculations are based on percentage by weight?
Regardless, it appears that fermentation of brown rice reduces phytic acid levels to almost nothing.
Great informative post.
2 things.
First — is the brown rice figure a typo? 12509 ?
Second – 100 grams of cocoa powder is a heck of a lot of cocoa and a bit misleading because its being compared to regular foods.