What is a testosterone booster?

In one line

A testosterone booster is the umbrella name for supplements that claim to make the body produce more of the male hormone testosterone.

What is a testosterone booster?
A supplement said to raise the male hormone
You often see the name 'testosterone booster' in supplement shops and online. This post explains what kind of hormone testosterone is, what goes into boosters, and what research has found.
In one line
Supplements that claim to raise the male hormone
'Testosterone booster' is the umbrella name for supplements that claim to help the body make more testosterone on its own. There is no fixed recipe; many products mix several plant extracts with vitamins and minerals.
What is testosterone?
The best-known male hormone
A 'hormone' is a substance made in one part of the body that travels in the blood and carries a signal to another part. Testosterone is the best-known male hormone and is made mainly in the testicles. Women have it too, but in much smaller amounts.
What it does
Muscle and bone, beard and a deeper voice
In both sexes, testosterone helps control sex drive and helps muscle and bone grow. In males it also drives facial and body hair, the deeper voice of puberty, and sperm production.
Real testosterone is a drug
Prescribed by doctors and controlled by law
Testosterone itself is a prescription drug. Man-made drugs modeled on testosterone are called 'anabolic steroids', and the U.S. puts testosterone and these drugs on its list of tightly controlled substances. Boosters are not these drugs; they are sold as supplements.
Common ingredients (1): plants
Fenugreek, tribulus, tongkat ali, maca
Common plant ingredients in boosters include fenugreek, tribulus (puncture vine), tongkat ali, maca and ashwagandha. Fenugreek is an herb whose seeds are used as a spice. They usually come as an 'extract', made by soaking the plant in water or alcohol and collecting what dissolves out.
Common ingredients (2): vitamins and minerals
Many products hold far more than the recommended amount
Vitamins and minerals such as zinc, vitamin B6 and magnesium are also common. A survey of popular boosters found that, among products containing vitamin B6, half held more than eight times the daily recommended amount. Some products went over the daily upper limit, the most thought safe to take, for zinc, magnesium and others.
Claims vs evidence
Most ingredients had no evidence
A survey of popular online boosters found that nine in ten advertised that they raise testosterone. But only about 1 in 4 of their ingredients had a study showing a rise in testosterone. For most of the other ingredients, no research on testosterone could be found at all.
When given to people
Most did not raise testosterone
When studies that gave booster ingredients to people and compared them with a dummy pill were pooled, most ingredients did not raise testosterone. Only a few showed a rise, such as some supplement ingredients given to men who exercise, and tongkat ali and ashwagandha. Fenugreek raised it slightly, but the conclusion was that this does not back up booster claims.
A common myth
Natural ingredients, so it must be safe?
No. In the U.S., supplements do not need government safety approval before they are sold. Among supplements the FDA warned about for hidden drugs, close to nine in ten of those sold for muscle building contained synthetic steroids or steroid-like substances.
Summary
Supplements that claim to raise the male hormone
A testosterone booster is a supplement mixing plant extracts with vitamins and minerals that claims to make the body produce more testosterone. In human studies most ingredients did not raise testosterone, and 'natural' does not mean safe. Words worth knowing too: testosterone, anabolic steroids, zinc.