Do men have estrogen? Yes, and you need it in range

Estrogen is not a female hormone that wandered into a man's body. It is part of normal male physiology, and the form labs measure is estradiol.

In a 2013 trial, Finkelstein and colleagues lowered men's own hormones and added back testosterone, with or without a drug that blocks estradiol. Low estrogen mainly drove the rise in body fat, and low testosterone and low estrogen both cut sexual function. The authors concluded that estrogens have a fundamental role in body fat and sexual function in men.

Bone is part of it too. In a one-year trial in older men, blocking estradiol with anastrozole lowered spine bone density compared with placebo (Burnett-Bowie and colleagues, 2009). An Endocrine Society statement lists bone, muscle, fat tissue, blood vessels, and the brain among the tissues estradiol acts on (Rosner and colleagues, 2013).

So the goal is a level in range, not zero.

Puffy nipples or breast growth do not prove a hormone problem. MedlinePlus says it is important to find out whether the growth is breast tissue or extra fat, and that obesity is the most common cause of breast growth due to fat.

Only a blood test shows estradiol. Ask for estradiol together with total testosterone, and read both with a clinician. A number alone is not a diagnosis.

One caveat on the lab side: the Endocrine Society statement says very low estradiol concentrations are too low for routine methods to measure accurately or precisely, and results still differ from method to method.

Units: testosterone is reported in ng/dL or nmol/L. Estradiol is reported in pg/mL, with pmol/L as the SI unit (1 pg/mL = 3.671 pmol/L).

Our guide to how to test testosterone covers timing and test types. Our free vs total guide covers SHBG, the protein that carries both testosterone and estrogen in the blood.

Most estradiol in men is made from testosterone by the aromatase enzyme. Finkelstein and colleagues put it at more than 80% of circulating estradiol, with a small share coming straight from the testes.

Early studies found higher estradiol in obese men than in lean men and put it down to more aromatase activity in fat tissue. A 2025 review by Tsutsumi and colleagues says later work found this is not consistent: estradiol is not raised in every obese man with low testosterone, and may even be lower.

MedlinePlus and the NHS list other causes of breast growth in men. No source here says these raise estradiol, but a clinician will ask about them:

In the research on this page, the lifestyle lever with evidence is weight loss in obese men. Corona and colleagues pooled 24 studies of weight loss in obese men in 2013. A low-calorie diet and bariatric surgery were both linked with a rise in total testosterone, and weight loss was also linked with a fall in estradiol. Men who lost more weight saw a bigger testosterone rise.

The caveat, from Tsutsumi and colleagues in 2025: weight-loss programs have not always produced a clear drop in estradiol.

Medicines, alcohol, and any anabolic steroid use are on the cause lists for breast growth (MedlinePlus; NHS). Go over them with a clinician rather than changing a prescription on your own.

The one drug tested here, anastrozole, lowered estradiol but cost bone density (see below). That is why the clinician conversation is not optional. Nothing on this page replaces it.

The drugs that block aromatase are medicines a doctor decides on. Anastrozole is the one used in the trials on this page. In a one-year, double-blind, placebo-controlled trial in 69 men aged 60 and over, anastrozole lowered estradiol, and spine bone density fell compared with placebo (Burnett-Bowie and colleagues, 2009). The authors concluded that in older men it appears to lower bone density and does not improve skeletal health.

That makes an aromatase inhibitor a doctor's decision, never a do-it-yourself one.

Store supplements are a different story. Chrysin taken by mouth has low bioavailability, mainly because the body breaks most of it down (Walle and colleagues, 2001). In a 21-day study, honey and propolis containing chrysin did not change urinary testosterone in men (Gambelunghe and colleagues, 2003).

DIM and zinc: we found no good human evidence in men that either lowers estradiol.

Zero is not the goal. In the Finkelstein trial, the percentage of body fat rose in every group when the conversion of testosterone to estradiol was blocked.

Bone pays as well. A year of aromatase inhibition in older men lowered spine bone density compared with placebo.

Estrogen in a man is a load-bearing wall. Knock it out, and parts you wanted to keep come down with it.

Enlarged breasts in men are usually harmless, per MedlinePlus. Some changes still need a doctor's appointment. MedlinePlus and the NHS list these: