Guide · Oct 13, 2026
Is Soy Good for Men? What the Hormone Studies Show
Does soy lower testosterone? What a 2021 meta-analysis of 41 clinical studies found, plus protein per serving of tofu, tempeh, edamame and soy milk.
By the ProstateFoods editorial team · Last updated
By the ProstateFoods editorial team · Last updated October 13, 2026 Short answer: Eating soy doesn't appear to change men's hormones. A 2021 meta-analysis of 41 clinical studies found no significant effect of soy protein or isoflavones on testosterone, free testosterone, estrogen or SHBG in men [1]. Tofu, tempeh, edamame and soy milk are good sources of protein.
What the studies found
| Hormone | Men measured | Effect of soy or isoflavones |
|---|---|---|
| Total testosterone | 1,753 | No significant effect |
| Free testosterone | 752 | No significant effect |
| Estradiol | 1,000 | No significant effect |
| Estrone | 239 | No significant effect |
| SHBG | 967 | No significant effect |
Source: Reed et al., Reproductive Toxicology, 2021 [1].
Soy has not been shown to treat or prevent prostate conditions either. It's simply a protein food that fits a plant-forward eating pattern.
Protein in soy foods
| Food | Serving | Protein | Calories |
|---|---|---|---|
| Tempeh | 1/2 cup (83 g) | 16.8 g | 159 |
| Tofu, firm, calcium-set | 1/2 cup (126 g) | 21.8 g | 181 |
| Edamame, prepared | 1 cup (155 g) | 18.5 g | 188 |
| Soy milk, unfortified | 1 cup (243 g) | 7.9 g | 131 |
Nutrient values are from USDA FoodData Central, SR Legacy (April 2018 release), calculated per the serving shown from USDA's per-100 g figures and USDA portion weights. Values vary by variety, brand and growing conditions. [2]
Using soy
- Press firm tofu, cube it and roast at 425°F until crisp.
- Steam frozen edamame in the microwave as a snack. Crunchy roasted edamame works when you have no frozen bag on hand.
- Crumble tempeh into chili or pasta sauce.
Thyroid and medication: if you take thyroid hormone, take it apart from soy foods, as your pharmacist advises.
Sources
- Reed KE, Camargo J, Hamilton-Reeves J, Kurzer M, Messina M. Neither soy nor isoflavone intake affects male reproductive hormones: an expanded and updated meta-analysis of clinical studies. Reprod Toxicol. 2021;100:60-67. https://pubmed.ncbi.nlm.nih.gov/33383165/
- U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy (2018). https://fdc.nal.usda.gov/
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ProstateFoods writes about food, not treatment. Nothing here is medical advice or a claim that any food treats, cures or prevents a disease. Talk to your doctor before changing how you eat, especially if you take medication or have a health condition. See our medical disclaimer. Photo: Edamame in a tray by Jiafei Slay Queen, CC0, via Wikimedia Commons.
Frequently asked questions
Does soy lower testosterone in men?
A 2021 meta-analysis of 41 clinical studies found no significant effect of soy or isoflavones on testosterone or estrogen in men.
How much protein is in tofu?
About 22 g in half a cup of firm, calcium-set tofu, based on USDA data.
Is soy good for the prostate?
Eating soy hasn't been shown to treat or prevent prostate problems. It's a useful protein food.