Know what you're putting in your body.

158 herbs, nutrients, and compounds. What the science says, what tradition knew, and what to watch for. Founding members keep this running.

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HEART FUNCTION

Soy

Glycine max

also known as soy isoflavones, soybean

Moderate (the actual evidence is more nuanced than the panic suggested)

A bean cultivated for over five thousand years in East Asia, where traditional preparations — tofu, tempeh, miso, edamame — have been dietary staples without harm to the populations that eat them. Modern controversy around soy and hormones has not held up under careful research. The real story is more interesting and less alarming than either side of the fight made it seem.

Modestly lowers LDL cholesterol with regular intake — recognized by the FDA as part of a heart-healthy diet
May ease menopausal hot flashes for some women, particularly those who can convert daidzein to the more active equol
Complete plant protein — contains all essential amino acids in usable proportions
Soy isoflavones may modestly support bone density in postmenopausal women
Populations with high traditional soy intake have lower rates of breast cancer, prostate cancer, and cardiovascular disease — though many factors contribute
Fermented forms (tempeh, miso, natto) are easier to digest and richer in K2 than non-fermented soy

Common allergen — soy allergy is one of the major food allergies, particularly in children

Concern about soy and breast cancer recurrence has not held up in serious research — current evidence suggests moderate dietary soy is safe or beneficial for breast cancer survivors

Use caution with thyroid medication if eating very high amounts of soy — soy can reduce absorption of thyroid hormone, so separate doses by at least 4 hours

Concentrated soy isoflavone supplements behave differently from soy as food — the safety picture is less clear

Soy infant formulas should only be used when medically indicated — choose breast milk or cow's milk formula otherwise

Most US soy is genetically modified and grown with herbicides — choose organic or non-GMO if that matters to you

The traditional Asian dietary pattern includes soy with rice, vegetables, fish, and fermentation — copying just the soy without the rest of the pattern misses the context

NCCIH — Soy · MedlinePlus Herbs & Supplements · NIH NCCIH Herbs at a Glance

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