Fenugreek

Fenugreek is an annual legume whose seeds are used across South Asian, Middle Eastern and North African cooking. Known as methi in India, the seeds and leaves are both eaten, and the seed is the part used in supplements.

Compounds of interest include steroidal saponins, 4-hydroxyisoleucine and soluble fibre. Extracts are usually standardised to saponin content, and several branded extracts dominate the research literature.

One genuinely useful thing to know before buying: fenugreek contains sotolon, the compound responsible for the smell of maple syrup. At supplemental doses it is excreted in sweat and urine, and users frequently report smelling noticeably of maple syrup. This is harmless, entirely predictable, and the single most common surprise reported by first-time users.

The proposed testosterone mechanism involves inhibition of the enzymes that convert testosterone into other hormones, which would in principle leave more testosterone available rather than increasing production.

4-hydroxyisoleucine is a distinctive amino acid found in fenugreek that stimulates insulin release in a glucose-dependent manner, which underpins the separate research strand on blood sugar handling.

The soluble fibre content, around 25 per cent of the seed by weight, slows gastric emptying and carbohydrate absorption. This is a straightforward and uncontroversial effect, and arguably the most reliable thing fenugreek does.

Testosterone research is mixed. Several trials using specific branded extracts have reported improvements in free testosterone and in self-reported measures such as libido and energy, while others have found no change in hormone levels.

A recurring criticism is that a substantial share of the favourable trials are funded by the companies producing the branded extracts, and independent replication is limited. Where effects are reported they tend to be on self-reported measures more than on measured hormone concentrations.

Blood sugar research is more consistent, with several trials reporting improvements in glucose measures, plausibly explained by the fibre content as much as anything more exotic. That is the better-supported use, though it is not what the sports nutrition market sells it for.

Fenugreek is a food and is well tolerated. The most common effects are digestive: bloating, gas and loose stools, largely from the fibre content, plus the maple syrup body odour.

As a legume, fenugreek can cause allergic reactions in people sensitive to peanuts or chickpeas, and this cross-reactivity is worth being aware of.

It lowers blood sugar and has a mild effect on how readily blood clots. Check with your doctor before use if you take regular medication or if your blood sugar is being managed.