Phytates/Phytic acid - nutritional nightmare?
February 22, 2021 8:06 PM   Subscribe

How concerned should I be with phytic acid in grains and nuts, and if I should be concerned, how should I prep food for it? Please link to reputable references if possible!

I've had to shake up my diet lately, which has got me scouring nutritional websites. I've once again encountered the phytic acid debate, and I can't make heads or tails over what's real science or not, too much information seems to come from wannabe influencers. Metafilter, help me with the definitive and evidence-based take on this subject!

1) Phytic acid - is it legitimately an "anti-nutrient"? Should vegetarians/vegans be concerned? I've read that along with being an anti-nutrient, it's also a beneficial antioxidant, so it's not totally bad for your diet.

2) How should foods be prepared, if phytic acid is a legitimate concern? I've read so many different takes!
* soak it in water in room temperature (kinda feel like this wouldn't be safe to do overnight?)
* soak it in water in the fridge
* add acid to it
* for beans, soak in an alkaline solution with baking soda instead
* for oats, soak with rye flour because oats specifically have low amounts of phytase and can't get rid of the phytic acid on its own???

3) Personally, should I be soaking my grains/legumes/nuts? (I draw the line at sprouting and fermenting - I will never be assed)

Personal details:
* I've always been on the edge of having low iron levels.
* I'm pescetarian, with no dairy, but I infrequently eat fish nowadays (especially since, with my gallstones, I'm loathe to eat fatty fish).
* I rely a lot on grains, mostly steel-cut oats and rice, trying to get back into wheat berries. I usually soak rice and wheat berries for 10 minutes right before cooking, but I don't soak my oats at all.
* I like having a half cup of nuts a day, I always try to buy it roasted anyway (I've read that roasting nuts decreases phytic acid).
* The most iron-rich food I eat everyday is tempeh, I eat a lot of it.
* I've been having digestive issues which is why I've been eating tempeh, the fact that it's fermented and therefore has huge amounts of nutrients available, with little phytic acid, is a plus, but in the near future I want to transition back to eating lentils (tempeh is expensive!).
* I already know to eat Vitamin C with iron-rich foods like tempeh, and I avoid drinking caffeine within an hour of eating iron-rich foods too.
posted by facehugger to Food & Drink (4 answers total)
Here's what the Harvard School of Public Health has to say:

"People who are at high risk for diseases related to mineral deficiencies, such as osteoporosis with calcium deficiency or anemia with iron deficiency, may wish to monitor their food choices for anti-nutrient content. Another strategy could be to alter the timing of eating foods with anti-nutrients. Examples are [...]taking a calcium supplement a few hours after eating a high-fiber wheat bran cereal that contains phytates.

Studies on vegetarians who eat diets high in plant foods containing anti-nutrients do not generally show deficiencies in iron and zinc, so the body may be adapting to the presence of anti-nutrients by increasing the absorption of these minerals in the gut. [3]

Because of the potential health benefits of phytic acid, if your diet contains a variety of plant-based and lean animal foods, you don’t have to worry about how much you are eating. Only those already at risk for nutrient deficiencies of the minerals mentioned or those who eat only plant foods such as vegans may need to consider reducing phytic acid in the diet."

posted by lulu68 at 10:20 PM on February 22 [2 favorites]

A lot of your questions focus on advice for extremely restrictive diets for health issues. The internet in general is a poor place for nutritional advice. Have you tried talking to a real nutrtionist?

Also, if beans, grains, nuts, and seeds caused serious problems with nutrient absorption under normal unrestricted dietary conditions, a lot of well fed people would be malnourished all over the world. Many people worldwide basically eat beans and rice as their main source of subsistence and get adequate nutrition from that plus some vegetables. If you're reading about a diet fad and it sounds like pseudoscience and you cannot easily find reputable sources, there's probably a reason for that.
posted by shadygrove at 10:23 PM on February 22 [8 favorites]

This seems obsessive to me. Have you seen a nutritionist?

Borderline low iron levels are insanely common if you are a menstruating woman. Are you feeling any effects from the low iron? Is there a reason supplements are off the table?

Anecdata: I was borderline anemic for years and have bounced around the vegan-vegetarian-pescetarian spectrum. I’ve never heard anything about phytic acid being the problem. I got my levels up through taking supplements for years but now that I eat a more balanced diet I don’t need them anymore. I don’t do any of this soaking business — I usually eat canned beans because I am lazy. YMMV.
posted by vanitas at 10:03 AM on February 23 [1 favorite]

I have no info on phytic acid - a nutritionist/dietitian would be a good move. I chimed in to say that inorganic arsenic can be a problem with people who eat a rice-heavy diet. This seems to be a risk that takes decades to increase the cancer rate, but there are simple ways consumers can mitigate these risks.

I refer you to this FDA report on the subject, It's long, but the rinsing and cooking techniques discussed begin on page 97.
posted by citygirl at 11:58 AM on February 23

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