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Testosterone Supplements: What Trials of Four Ingredients Found

Posted on: Edited on: ~8 min read

Products sold as testosterone boosters often put strength, sexual desire, and hormone levels on the same label. The human studies did not always measure the same thing.

If a supplement raises testosterone, what should change — the blood number, or how I feel?

To show a testosterone change, a study needs a blood measurement and a comparison group. Feeling more desire or lifting more weight can matter to you, but neither tells you that your testosterone rose. A hormone increase from a person's own starting value is also less convincing if the placebo group changed too.

The men in these trials differed. Some had barely lifted before; others already trained regularly. Most were not enrolled because a doctor had confirmed low testosterone. A result in one group does not answer whether the same supplement helps a man whose testosterone is low or who already takes prescribed testosterone.

What did trials of these four testosterone supplements find?

The four ingredients covered here have trials that measured testosterone. Ashwagandha has one positive training trial. In a trial of a different extract, the change did not clearly exceed placebo. ZMA, a zinc-containing blend, did not beat placebo on hormones in trained men. Maca improved some self-reported outcomes without raising testosterone. D-aspartic acid's short positive result in untrained men has not held up in trials of men who lift.

Has ashwagandha been shown to raise testosterone?

Yes, in one small trial where men also began lifting weights. Another trial with a different ashwagandha extract found a rise over time in men, but not a clear difference from placebo.

Wankhede and colleagues[1] assigned 57 men with little weight-training experience to 300 mg of KSM-66 root extract twice a day or placebo while both groups trained for eight weeks. Fifty finished. Testosterone rose about 96 ng/dL in the extract group and 18 ng/dL in the placebo group. The larger rise with KSM-66, compared with placebo, was the positive finding. The maker supplied the extract. These men were not recruited for diagnosed low testosterone, and the study tested an addition to training.

Lopresti and colleagues[2] used 240 mg a day of Shoden for 60 days in stressed adults:

  • Testosterone rose among the men who took it compared with their own starting levels.
  • That rise did not clearly beat placebo.

Shoden and KSM-66 are different extracts; neither result establishes what an unnamed root powder would do.

What did trials of the zinc-containing blend ZMA show?

The ZMA trials in trained men did not show a testosterone boost. Because ZMA combines three nutrients, these trials cannot tell you what zinc alone would do for someone who is deficient.

In an eight-week placebo-controlled study[3], 42 resistance-trained men took ZMA or placebo while following the same training program:

  • The trial could not distinguish a testosterone difference between the groups from chance.
  • They did not differ on other measured hormones.
  • They did not differ on training outcomes.
  • Cytodyne Technologies funded the study; the authors said they analyzed the results independently.

A second study of 14 exercising men[4] found no increase after ZMA:

  • Total testosterone did not increase.
  • Free testosterone—the portion not bound to blood proteins—did not increase.
  • That smaller study had no placebo comparison.

ZMA combines zinc, magnesium, and vitamin B6. Neither study isolates zinc. Getting enough zinc is a nutrition question, particularly if your intake is low; taking extra zinc when you already get enough is a different claim.

Has maca been shown to raise testosterone?

No clear rise against placebo appeared in either of the two men's trials that measured it. Some men reported better sexual desire or other symptoms, which is a separate outcome.

Gonzales and colleagues[5] gave 57 healthy men 1.5 or 3 g a day of gelatinized maca—root processed to reduce its starch—or placebo for 12 weeks:

  • From week eight, more men taking maca reported increased sexual desire.
  • Testosterone did not differ from placebo.
  • A company supplied the tablets.

In a later study[6], 80 men over 40 with symptoms but without confirmed low testosterone completed 12 weeks of about 5 g a day of gelatinized maca or placebo:

  • Scores for symptoms and sexual function improved more on maca.
  • Neither total nor free testosterone changed more than with placebo.
  • Men with very low morning testosterone and men recently taking prescribed testosterone were excluded.
  • The study reported a government grant and no conflicts of interest, but three authors worked for product companies. That connection is worth considering when weighing the symptom finding.

Neither trial tested the claim that red maca is the form that raises testosterone.

Has D-aspartic acid been shown to raise testosterone?

One short trial found a rise in men who did not train regularly. Trials in men who lift found no rise at 3 g a day, and one found a fall at 6 g a day.

Topo and colleagues[7] gave 23 men a sodium D-aspartate product at about 3.12 g a day for 12 days and compared them with 20 men on placebo. Testosterone rose in the treated group. The study's researchers had developed the product, and the study did not show whether the change persisted or affected symptoms.

Willoughby and colleagues[8] found no testosterone change after 3 g a day for 28 days in resistance-trained men. In a 14-day trial[9], 3 g again did not differ from placebo. At 6 g in that trial's trained men:

  • Total testosterone fell.
  • Free testosterone fell.

A 12-week trial[10] at 6 g found no testosterone benefit. Whether men with confirmed low testosterone respond, and whether any short rise lasts or changes how they feel, remain open.

What are signs of low testosterone, and can I tell without a blood test?

You cannot tell from symptoms alone. Reduced sex drive, fewer spontaneous erections, low energy, and reduced muscle mass can occur with low testosterone, but they can have other causes. The Endocrine Society's patient guide[11] lists these among possible signs and symptoms.

The society's clinical guideline[12] calls for compatible symptoms or signs and consistently low blood testosterone. A doctor normally checks morning fasting total testosterone and repeats the measurement on a separate morning before making the diagnosis. A symptom quiz or a single afternoon reading cannot settle it.

What should I check on the label before I buy a testosterone supplement?

Check the exact ingredient, its amount per serving, how many servings you would take each day, and whether that is the preparation the trial used. A “clinically studied” phrase may refer to a different extract, a different combination, or a study of desire rather than testosterone.

For ashwagandha, the positive training trial used 300 mg of KSM-66 twice daily, or 600 mg across the day. A bottle's amount per serving only matches that daily amount if you count the servings. Shoden at 240 mg daily was the trial whose testosterone change did not clearly beat placebo. Grams of generic root powder do not equal either named extract.

For zinc, the Supplement Facts amount is elemental zinc. ZMA also contains magnesium and vitamin B6, so a ZMA hormone claim is not proof about zinc alone. For maca, Gonzales used 1.5 or 3 g of gelatinized root daily—1,500 or 3,000 mg—and Shin used about 5 g, or 5,000 mg, of gelatinized powder. One sample label[13] lists 250 mg of 4:1 extract as “equivalent to 1,000 mg” of root. On that label, 4:1 means the 250 mg extract was made from 1,000 mg of root; the larger number is not the extract weight in the capsule. Neither trial tested that extract, and a color name does not identify either trial preparation.

For D-aspartic acid, read whether the product is D-aspartic acid or sodium D-aspartate and count the daily grams. The short positive study used the sodium form at about 3.12 g; 6 g lowered testosterone in one trained-men trial. A blend with several hormone ingredients cannot tell you which one caused any change.

What should I take if I am already on testosterone?

The trial populations did not test that combination, and the maca study specifically excluded men who had recently used testosterone treatment.

If testosterone is already prescribed to you, ask the clinician who prescribes it before adding a hormone-marketed supplement or changing the prescription. The Endocrine Society guideline[12] calls for follow-up that checks your response and adverse effects.

The bottom line

The four ingredients do not offer one reliable way to raise testosterone. One ashwagandha extract showed a rise during resistance training, while another trial did not show a clear advantage; ZMA trials were mixed, maca improved desire without raising the hormone, and D-aspartic acid results depended on the study and amount. Match any claim to its measured outcome before treating it as a testosterone result.

If low testosterone is your concern, discuss symptoms and repeat morning blood tests with a clinician. A supplement bottle cannot establish the diagnosis or replace a treatment plan for confirmed deficiency.

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References

  1. Wankhede et al.: ashwagandha and resistance training ↩
  2. Lopresti et al.: Shoden and hormone measures ↩
  3. Wilborn et al.: ZMA during resistance training ↩
  4. Koehler et al.: ZMA and testosterone ↩
  5. Gonzales et al.: maca, desire, and testosterone ↩
  6. Shin et al.: maca in older men with symptoms ↩
  7. Topo et al.: D-aspartate and testosterone ↩
  8. Willoughby et al.: D-aspartic acid in trained men ↩
  9. Melville et al.: 3 g and 6 g of D-aspartic acid ↩
  10. Melville et al.: 12 weeks of D-aspartic acid ↩
  11. Endocrine Society: hypogonadism in men ↩
  12. Endocrine Society: testosterone therapy guideline ↩
  13. NIH Dietary Supplement Label Database: maca extract example ↩