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 Michael Gonzales · Last updated
By Michael Gonzales · 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/
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.
Written by
Michael Gonzales
Founder & Editor
Michael Gonzales is the founder of Cloudalien Technologies LLC, the company that owns ProstateFoods, and he edits every page on the site. ProstateFoods publishes everyday recipes, food lists and grocery guides for men who want to eat well. Michael is not a doctor or registered dietitian, so nothing on ProstateFoods is medical advice.