Do “testosterone boosters” work? What the evidence and lab reports say

The one claim that is allowed

EU Regulation 432/2012 lists the health claims foods may make. The only one about testosterone is for zinc: “Zinc contributes to the maintenance of normal testosterone levels in the blood”, and only for foods that are at least a source of zinc [1]. Great Britain kept the same claim in its register [2]. “Maintenance of normal levels” is not the same as raising them.

No herb has an authorised testosterone claim. Tribulus, maca, fenugreek, ashwagandha and tongkat ali have no authorised health claims at all in the EU or GB, so labels and adverts that promise more testosterone, muscle or libido from them are not using an approved claim.

Zinc and ZMA

Zinc deficiency is linked with low testosterone. In a small US study, restricting zinc in four young men for 20 weeks lowered their serum testosterone (from 39.9 to 10.6 nmol/L on average), and giving zinc to nine marginally deficient older men for 3 to 6 months raised it from 8.3 to 16.0 nmol/L [3].

In men who already get enough zinc, the picture changes. A German study of 14 regularly exercising men taking the zinc, magnesium and vitamin B6 product ZMA found serum zinc rose but total and free testosterone did not change [4]. An 8-week double-blind trial in 42 resistance-trained men found no difference from placebo in hormones, strength or body composition [5].

Dose matters: 25 mg a day is EFSA’s adult upper level for zinc from all sources and the UK Expert Group on Vitamins and Minerals’ safe upper level for zinc from supplements [21][22]. Several men’s products give exactly 25 mg, so stacking them with a multivitamin can take you over. Long-term high zinc can cause copper deficiency.

Tribulus

A 2014 systematic review of 11 studies found tribulus did not raise testosterone in humans; the only human rises were seen when it was part of a combined supplement. The authors concluded that marketing claims are unsubstantiated [6].

Maca

In a 12-week double-blind trial, men aged 21 to 56 took 1.5 g or 3 g of maca a day or placebo. Maca had no effect on testosterone, oestradiol, LH, FSH or prolactin at any point [7]. Maca is sold for libido and energy rather than hormones; it has no authorised health claim.

Fenugreek

A 2020 meta-analysis pooled four randomised trials of fenugreek extract and found a significant effect on total serum testosterone [8]. Four trials is a small base, the extracts were standardised products that may differ from the seed powder sold in shops, and it is not an authorised claim.

Ashwagandha

In a 16-week crossover trial in 57 overweight men aged 40 to 70 with mild fatigue, an ashwagandha extract was linked with a 14.7% greater rise in salivary testosterone than placebo, with no difference in fatigue, vigour or sexual well-being [9].

Safety is the bigger question. Denmark’s food authority says ashwagandha is illegal to sell in foods there after a DTU risk assessment found effects on sex hormones and reproduction and possible effects on metabolism and the immune and central nervous systems [16]. Germany’s BfR says children, pregnant or breastfeeding women and people with liver disease should not take it and could not set a safe intake [17]. France’s ANSES advises against it in pregnancy and breastfeeding, under-18s, people with thyroid, liver or heart conditions and people taking sedatives [18]. In the UK, the Committee on Toxicity discussed draft statements in May and September 2026 [19][20]; no final statement had been published on 26 October 2026. We compare ashwagandha separately, with this note, on our ashwagandha page.

Boron

The main human study often quoted gave 10 mg of boron a day to eight men for one week; free testosterone rose and oestradiol fell [10]. Eight men for seven days is far too little to say anything useful. We found no boron supplement sold in the EU or UK with an independent lab report, so we list none.

Tongkat ali, turkesterone and things we never list

Tongkat ali (Eurycoma longifolia) is not authorised as a food in the EU. EFSA could not establish the safety of a root extract in 2021 because genotoxicity could not be ruled out [13]. The Dutch NVWA has warned against and acted on products containing it [14], and Norway’s Mattilsynet says it is not allowed as food or a supplement [15]. We do not list it, whatever its lab report shows.

We also never list DHEA, prohormones, SARMs, “research only” products, medicines or banned ingredients. Turkesterone and fadogia are left out too: we found no authorised food status or independent reports that would justify listing them.

What the “booster” products themselves contain

A 2020 US study of 50 products sold as “T boosters” found 90% claimed to boost testosterone, but only 24.8% of their ingredients had any data showing a rise, 10.1% had data showing a fall, and many contained vitamins and minerals far above daily needs, some above the upper level [11].

A 2019 study of the five best-selling products on Amazon found that of 37 human studies on their main ingredients, 30% showed a rise in testosterone, 46% no effect, 3% a fall and 22% were indeterminate [12].

What the lab reports show

Whatever the ingredient, you should know what else is in the capsule. We only list men’s health products with an independent report from an accredited lab, and herbal products need a lead, cadmium, mercury and arsenic result to be marked lab verified. EU law sets maximum lead, cadmium and mercury levels for food supplements [23].

Of the 15 products we list, 7 have numeric heavy-metal results for a named batch, all within EU limits: five zinc supplements, a zinc + vitamin C product and an organic black maca extract. None of the multi-herb “men’s formulas” we found had a full numeric report for a matching sample, so they are labelled “Partial report”. One zinc report also found 14 mg zinc in a capsule labelled 20 mg. See the full comparison and the short answer.

Do testosterone boosters actually work?

For men with normal testosterone and enough zinc, the trials mostly found no rise: ZMA [4][5], tribulus [6] and maca [7] all came up empty. Fenugreek and ashwagandha have small positive results [8][9]. No supplement is authorised in the UK or EU to say it boosts testosterone.

Is zinc good for testosterone?

Zinc is needed to keep testosterone levels normal, and that is the one authorised claim [1]. Correcting a zinc deficiency helped in a small study [3], but extra zinc did not raise testosterone in men who already had enough [4].

Is tongkat ali banned in the UK and EU?

In the EU it is an unauthorised novel food after EFSA could not establish its safety in 2021 [13]; the Netherlands and Norway have acted against products [14][15]. It is not on Great Britain’s authorised novel food list either. We do not list it.

Is ashwagandha safe?

Regulators disagree. Denmark does not allow it in foods [16]; Germany and France advise some groups not to take it [17][18]; the UK review was still ongoing on 26 October 2026 [19][20]. Ask a doctor or pharmacist first if you have liver or thyroid problems, take medicines, or are pregnant or breastfeeding.

How much zinc is too much?

25 mg a day is EFSA’s upper level from all sources and the UK safe upper level from supplements [21][22]. Count every product you take.