Nuts and Phytic Acid: Should You Be Concerned?by
Mark Sisson Recently by Mark Sisson: Top 10 Junk Foods in Disguise
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...
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
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). Listen to Lew's recent podcast with Mark Sisson
May 18, 2012 Copyright © 2012 Mark's Daily Apple
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