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 |
Like what you’re reading? Get my free newsletter, recipes, eBooks, product recommendations, and more!
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.
Being a lay-person (and not a very bright one) I read the link you provided (just the abstract – I’m not sure I could have absorbed anything more detailed) concerning phytic acid prohibiting mineral absorption, but I came away puzzled. (Not surprising.)
First, the study seemed more focused on fiber as opposed to phytic acid. Second, the different experimental conditions made conclusions problematic. Third, and I’ll quote directly from the abstract here: “Finally, it must be borne in mind that fiber and phytic acid occur together in fiber-rich diets and, thus, it is difficult to separate the effects of fiber and phytate in the utilization of most essential polyvalent metallic ions.” It goes on to say that increasing fiber intake (and obviously phytic acid) would not be expected to have a detrimental effect on mineral absorption if we also increased protein, and ascorbic, citric, and oxalic acids.
1. How do we know it isn’t the fiber causing the issues with mineral absorption instead of the phytic acid?
2. If we’re getting sufficient protein and the above-mentioned healthy acids, should it even be an area of concern?
I promise I’m not trying to be a smart ass! But if there’s one thing I’ve learned in the two years since I developed an auto-immune disease it’s to question, question, question! So what am I missing? I’ve never noticed any issues with nuts myself. I’ll go weeks without eating any, and then other times when I’ll have a handful of pecans daily. But for those of us who follow a Paleo diet, taking away foods that would have been easily available to primitive man seems to defeat the purpose of “eat what you can hunt or gather”.
There are many, many studies showing phytic acid inhibits mineral absorption. I chose one. It’s not a controversial subject at all. In fact, phytic acid is used by some practitioners therapeutically to chelate minerals from the body when they are in excess (as in iron overload, for example).
The answer is: They don’t know. How is it that apricot seeds (which contain cyanide) can kill cancer cells, but not harm the rest of the body. Again, no one knows, but one thing you can be sure of, if it was nature created, there is some good reason and good benefit from consuming it.
I don’t care what so called “experts” say, they, nor anyone else can know exactly how all the ingredients contained in nature’s products work inside the body, and I don’t care how many “studies” they do. It is impossible to discover.
And BTW, all almonds are now required to be pasteurized, so what benefit would there be to drinking highly processed almond milk (with carageenan–creates sores all over my body) with almonds that have no nutritional value.
I finally found a site online that has truly raw almonds, but they are not USDA certified (I don’t care if they are not) and I will now be buying my truly raw almonds from them. If you have a problem with raw almonds, DON’T EAT THEM. Try something else. Good God, common sense people!
Phytate clarification questions:
Does phosphorus content (e.g.listed for all foods in nutrition data database) correspond to phytic acid content? Phytic acid content is not listed.
Coconuts (according to the wikipedia reference) do not seem to contain very much phytic acid.
The reference also states that the phytic acid is found in the hulls of the nuts. Do you think this means if you purchase blanched almonds (and peel the brown away from the fresh coconuts after shelling them), you are removing most of the phytic acid?
Chris’ article states unfermented cocoa nibs are the problem, yet my understanding of processing chocolate is that of ALL cocoa nibs ARE fermented- before any additional processing occurs. Does this mean there still is that much phytate in undutched, unsweetened cocoa powder?
Thanks for the information! It is very concerning, as the recent “buzz” about why sodas are aging is due to the phosphorus content.
Hello Deb B,
Phosphorus is not necessarily linked with phytic acid. Meat has a lot of phosphorus, but no phytic acid. Phytic acid is only found in seeds (grains, legumes, oily nuts and seeds). Phytic acid is merely the storage form of phosphorus, but you can have free phosphorus as well, as in meat.
Coconuts do contain a moderate amount of phytic acid, but mostly in the form of a salt. Phytic acid salt, aka phytate (as in sodium phytate), does not have the chelating power of free phytic acid. This info is from a great article on phytic acid by Ramiel Nagel, and it’s found on the WAPF site.
The shell of the almond would be roughly analogous to the hull of a grain. The skin would have the tannins, which some consider to be toxic. However, tannins are part of the polyphenol family, which is actually an antioxidant. When you take isolated tannin, as in the form of liquid tannic acid for tanning hides, that would probably be toxic.
Most cacao nibs, whether roasted or raw, do go through some fermentation. There might still be a few raw chocolate companies that still use unfermented cacao beans/nibs. Personally, I think a full fermentation is a good idea because the microbes then complete their life cycle and die off. There’s quite a bit of “dirty” raw chocolate on the market.
The undutched, unsweetened cocoa powder on the market has been fermented and roasted, unless it’s actually advertised as being raw cacao powder that’s coming from a company that use unfermented cacao bean/nibs.
I don’t believe the phytic acid in chocolate is that big of a deal. I’ve weighed it out before, and it actually takes 21 tablespoons of cocoa powder to make 100 grams. So it’s not really fair to compare it to 100 grams of Brazil nuts.
Hope this helps!
Blessings,
Andrew
Many thanks for another clear and well-researched article. I read a few days ago – in passing, I don’t recall where – that phytic acid might be useful in preventing Alzheimers disease. Is this correct and is there any research which indicates, if correct, how much is needed? Many apologies if I’m confusing the issue.
Hi Chris. Thanks for the info. Very useful, as usual.
Can you point us to a source for those numbers in the chart? (It looks like you have a little “1” note there without a link.) Thanks very much!
It’s from this book: http://www.amazon.com/Food-Phytates-N-Rukma-Reddy/dp/1566768675
Chris,
Does a little acid (vinegar or lemon juice) aid in breaking down the phytic acid? Haven’t seen you mention that and I’m just going by the instructions in Nourishing Traditions, by Sally Fallon. As far as coconut flour, it seems it could still be baked with after soaking and adding another low fiber starch (tapioca or arrowroot) to absorb excess moisture before adding other ingredients. Any thoughts on that?
There’s no problem with doing that, but it does seem to change the texture of the final product.
Studies that I have read show that cultures consuming phytate containing foods go through an intestinal adaptation process. The body appears to be able to reclaim some level of mineral absorption after adjusting to the continual consumption.
This is true, but “some level” is key. The adaptation is limited, from what I understand.
At what temperature and for how long do you roast the nuts. Do all types of nuts get roasted the same temp/duration?
150-170 for several hours until they are crunchy.
Do you then roast them at a higher temperature?
So the overall nut preparation is along the lines of:
Soak in (slightly salted ?) water for 18 hours
Dehydrate for several (I do about 6) hours at about 150-170F (65-75C)
Finally roast them – but what temperature and duration here Chris?
I know that the dehydrating step essentially allows you to store them (wet nuts will go mouldy in a couple of days) but I’m just unsure of the final roasting step in terms of how to do it and also just what it achieves over and above the dehydrating.
For anyone thinking this looks complicated – I’ve been soaking and dehydrating for a while and it’s really not hard at all. Just buy some nuts and soak them immediately you get them home. Then store them in a jar once dried so you can use them whenever.
I think dehydrate and roast are the same process. I leave them in the oven at 170 degrees (my electric oven doesn’t go lower) for 12-15 hours, until they are nice and crunchy. You can’t go any higher in temperature without losing the nutritional value as I understand it.
Thanks Jane but apparently not – Chris said:
“dehydrating at very low temperatures (either in a food dehydrator or a low temperature oven), and then roasting or cooking the nuts”.
Chris? 🙂
Nice aricle Chris, although I also wonder about the possible benefit connected to partially reducing iron absorbtion in those who have elevated levels of iron saturation in the blood and low binding (me).
In case anyone is interested… here is a post I put up on PaleoHacks back in February on how I soak/dehydrate the nuts. Since then, we actually bought a deluxe Excaliber dehydrator and it works like a gem. I’ve given up the almonds/pecans completely since my July lipid numbers scared me, but we have just harvested several pounds of macadamia nuts from our tree and dehydrated them (didn’t soak em). So delicious!
Anyway.. soaking/rinsing/dehydrating almonds and pecans is a good idea if you insist on eating them (which I totally understand). In fac, they are actually sweeter (I think because of the partial ‘fermentation’) and more crispy/fluffy.
Here’s the link…
http://paleohacks.com/questions/12925/is-almond-butter-ok-on-the-paleo-diet/23225#23225
Kymberly,
I soak walnuts and almonds in a salty water for 12-16 hours. They don’t taste nearly as salty as store bought nuts do. I strain them but don’t rinse them off, just to keep some salt on them. My oven only goes down to 170 degrees, so I prop the door open just barely. This keeps the temp closer to 140-150 and lets the moisture out. I forget the exact number, but at higher temps you start destroying valuable nutrients.
For me walnuts usually take 12-14 hours, and almonds take 16-18 hours to bake. One other thing I have found is to take just a few out nearing the end time and let them cool before deciding if they are crunchy enough for your liking. They are less crunchy when they are warm, but after 5 minutes or so are cool enough to test. Then make sure to let them cool before sealing in any container so the moisture evaporates. Almonds tend to pop a little as they cool.
Now, about that dark chocolate…???
Not my chocolate!!! I just bought a bag of raw cacao and thought I had stumbled upon the perfect dessert when I mixed with some coconut oil and coconut flakes and made a “fudge”. Back to fruit for dessert I guess….
You can still eat it. Just don’t make it a staple part of your diet.
I don’t think you understand my love for chocolate…. 🙂
But maybe I just need more magnesium.
100g of cocoa powder would conceivably make a lot of actual chocolate since, by weight, chocolate is more cocoa butter than cocoa powder. I will have to experiment with this in making some chocolate and see how much powder:fat gets used. You know, for science’s sake 😉
I suppose you’re right. I didn’t actually think about how much cocoa powder and coconut flakes I use.
My recipe right now is:
3 T (~15g) unsweetened shredded coconut = 53mg phytic acid? (by my quick and dirty math)
2 T coconut oil, melted
1 T (~5g?) cacao powder = 90mg
This conceivably makes 4 little truffles (though realistically, it’s more like 2 servings). So, 70mg phytic acid per serving? Is my napkin math right? If so… whew! Not too bad.
By the way, Diane, I am enjoying your new podcast! I live in SF, too. Just moved here, actually — right around the same time I started really looking into paleo.
KJ- Cool, thanks so much. 🙂 If you haven’t already reviewed it in iTunes- please do so! I’m teaching a seminar next weekend in Manteca (90 mins outside of SF) if you know anyone interested in learning more about Paleo, send ’em over!
Thanks for the post! I’ve also experienced problems with nuts. When I was on an allergy-free diet (ie. Paleo but with rice and no nuts) I felt great. My symptoms disappeared within a few months. Then I moved to a Paleo diet and began eating nuts and ditched the rice. I noticed a gradual deterioration. I now avoid nuts since they give me stomach pain and are pretty much the only food I actually get cravings for when I eat it. I’ve once again embraced eating brown rice after soaking it in a fermented soaking medium (maybe 2-3 servings a week, so not much). Now I feel great again!
“Even the Paleo-beloved coconut has almost 400 grams of phytic acid per 100 gram serving.”
400 mg, not 400 g
Thanks for the proofread. I fixed it.
Thanks for the post. Grateful as always for the information. I replaced the grains in my diet–and my 5-grain granola–with buckwheat, nuts and seeds. Time to start soaking and dehydrating the nuts before baking…. How much phytic acid do pecans contain? Is there phytic acid in seeds, too? (Pumpkin seeds, sunflower, sesame)
All seeds contain phytate. Plants need phosphorous in order to grow properly, and phytate is basically phosphorous in chemically-locked-up form. It’s meant as food for the seed embryo, not as food for us. The methods for breaking it up are methods that trick the seed into thinking it’s in ideal germination conditions.
You’ll only avoid phytate if you don’t eat seeds. It’s a tradeoff. I’m glad people are wising up now to methods they can use to break up the phytate, since I don’t think most humans will abandon eating seeds anytime soon. But we aren’t adapted to them. I think only birds and some (all?) rodents are.
Hi Chris,
How do you recommend that GAPS dieters get enough glucose/carbs? I’ve been following Paul J’s recommendation of 400 daily calories from safe starches due to past fungal problems (now under control), but I want to try GAPS for gut health reasons. I’ve been eating the PHD for over a year, still with some constipation. I know white rice isn’t technically GAPS “legal,” but would it likely be okay because it is not a fermentable fiber? Thanks!
Gluconeogenesis? There is no dietary requirement for glucose in human beings. You’d wake up dead if there were, unless you sleep only two hours at a time.
Less flippantly, experiment on yourself and see what you can tolerate. Humanity has longer species experience with tubers than with seeds, so if I were advising someone who really wants to keep eating carbs, I’d tell ’em eat leaves, eat low-sugar fruits and have a sweet potato every now and again.
Good grief! What next? I checked the Wikipedia entry for phytic acid hoping for better news. What about the links to reduced cancers – the idea that phytic acid can retard cancerous growths by removing the minerals they need to thrive? And it sounds as if the phytic acid in legumes is directly linked to reduced colon cancer. The takeaway, for me, was that people in developing countries with poor access to basic nutrients may need to be concerned about this. But can’t we compensate by making sure to get enough magnesium, iron, etc from other sources – supplements or whatever?
Sounds like nuts may provide chemotherapy naturally. Wow!
People who eat more seeds get more cancer. This has been known since European and American doctors spent a lot of time among indigenous peoples. The folks who are saying phytates cure cancer are the ones trying to develop them as a drug.
Quote? Evidence? Statistics? You’re just sprouting nonsense, otherwise.
I don’t eat nuts because they make me feel terrible and I get uncontrollably addicted to them. A lot of people in the Paleo community are addicted to nuts and they often say that this a result of the body craving certain nutrients that they are lacking. I don’t personally believe this is true. Do you have any insight into nut addiction? I wonder if it might result from the body’s desire for carbohydrates when doing a low carb diet.
I get crazy nut addiction too! I now stay far away from nuts : ) But I don’t think it’s caused by a desire for carbs. I don’t eat a low carb diet; I eat a decent amount of fruit, starchy veggies, and soaked/fermented rice, yet I still get crazy cravings for nuts if I eat even a few. Seriously, chocolate has nothing on nuts, for me at least! I take 800mg of magnesium per day and that has helped in other ways, but not with the nut cravings…
I find them to be addictive as well. For me, I think it’s the combination of delicious fat and salt. Unsalted nuts will hang around in the pantry while the salted varieties will disappear waaay too quickly. Plus, unless they’re raw/dry roasted, they’re processed with junky oils. Bye bye nuts 🙁
I just can’t have nuts at home without regular trips to the container, so nuts are out. I don’t care why they are addictive, they are . The possible reason – high level of phytates prevent appropriate absorption of nutrients and body’s reaction – eat more food. Another possibility – nuts provide natural fat+carb combination that gets us in a trouble in a fast food case. The only kind of nut I can resist is macadamia and it is the lowest in carbs.
Looks like the only baking option – buckwheat sourdough. I already used the pancake as a pizza crust for my son.
If I eat enough fat I don’t crave carbs. I know what carb craving feels like and I don’t get that. I might choose to eat them anyway but it’s generally because I’m being bratty. It’s when my carb intake creeps up that I start in on the cravings again.
People who try to eat a high-protein diet with neither carb nor fat to back it are asking for trouble, and even Paleo isn’t supposed to be low-fat, no matter what Cordain says.
Thank you for the info! I have been wondering about this exact topic – I was happy to see your post today!!! It is so easy to substitute with nuts when first going primal/paleo! I have not tried baking with almond or coconut flour, but I have noticed that most paleo baking recipes use these… Sorry, to say, but it seems baking in general may be off limits (for the most part) for these types of diets. Especially, if you are working with any auto-immune issues or vitamin deficiencies.
Great post, Chris. I have this strong feeling that most people coming off years of SAD/vegetarian have a zinc deficiency (magnesium, too). It seems that copper may be less bound up by phytic acid than zinc (http://www.ncbi.nlm.nih.gov/pubmed/3373335), which can lead to a messed up copper:zinc ratio when eating lots of grains and nuts combined with minimal high zinc foods (ie. meat). This can continue on a paleo diet if someone is eating their beef with almond flour muffins or taking a zinc supplement right after eating half a dark chocolate bar.
Any info on phytic acid in potatoes and sweet potatoes?
Great comment Phoenix. I have pyroluria which leeches B6 and zinc from my body and resulting copper overload (confirmed with tests). This great post by Chris and your comment have convinced me to start prepping nuts properly and reducing consumption. Might start using more buckwheat flour to replace almond and coconut.
Would a good quality nut oil like organic expeller pressed macadamia nut oil have the same drawbacks?
Great article Chris, I’m glad you wrote this, people really do seem to go way over board with nuts, when they are seriously overrated. High doses of omega 6 and high levels of phytic acid and not exactly nice condiment for your average meal anyway. I think a good way to stop someone eating to many nuts, is simply to get them to shell the nuts themselves, the effort soon out ways the benefit.
Buying nuts in the shell also helps prevent rancidity, from what I understand.
Hi Chris –
Thanks for this post. One thing that might be helpful is an idea of what 100 grams of a nut means. A little online sleuthing tells me that a cup of shelled almonds works out to be about 125 grams, for what it’s worth.
Keep up the good work!
Thanks for posting Chris. I remember being astounded in school when I learned about phytates. I thought, how could nuts be bad for you? I’ve too learned to properly prepare them and use them in moderation.