Nutrition
Is plant protein inferior, and does soy negatively affect hormones?
Short answer
On a varied diet (legumes, soy foods, grains), plant protein readily covers the need for all essential amino acids. As for soy — it is one of the best-studied topics in nutrition. Soy isoflavones differ in structure from human oestrogen, and meta-analyses do not show a negative effect on testosterone in men or a higher risk of hormone-dependent cancers in women. The myth that soy 'feminises men' came mainly from rodent studies using doses incomparable with a human diet.
You do not need to combine rice and beans in one meal – your body collects amino acids over the day. Soy is safe: tofu, soy milk or edamame are food, not drugs. Human studies do not show effects on testosterone or cancer risk.
The myth came from rodent experiments with extracts at doses you could never eat. Unless you are eating kilos of isoflavones a day, soy is an ally, not an enemy.