Yerba Mate

Yerba mate is made from the leaves of Ilex paraguariensis, a holly species native to South America, where it is drunk socially from a shared gourd through a metal straw.

It supplies caffeine at around 0.7 to 2 per cent of dry leaf weight, less concentrated than guarana, alongside theobromine and a large quantity of chlorogenic acids and saponins.

Mateine, sometimes presented on labels as a gentler alternative to caffeine, is simply caffeine. The claim that it behaves differently has no basis in chemistry.

The alertness comes from caffeine antagonising adenosine receptors, with theobromine contributing a longer, flatter component.

The chlorogenic acids are the more distinctive part. These are the same class of compound found in green coffee bean, and they influence glucose handling and fat metabolism through separate routes from the caffeine.

Saponins in the leaf contribute the characteristic bitterness and have their own reported effects on lipid handling, though these are less well characterised.

Research has reported increased fat oxidation during exercise following yerba mate, with one frequently cited trial finding a meaningful rise in the proportion of energy coming from fat during moderate activity.

Trials on lipid markers and on satiety have reported favourable effects, though study sizes are modest.

Effects on body weight are small, in line with the whole thermogenic category. The caffeine and polyphenol content is real and worth having; expectations of substantial fat loss from it are not supported.

Yerba mate carries the usual caffeine considerations: restlessness, raised heart rate, disturbed sleep and digestive upset at higher intakes.

The temperature point above is worth taking seriously if you drink it traditionally. Letting it cool below scalding is a simple and complete fix.

Speak to your doctor before use if your heart rhythm or blood pressure is being managed, or if you take regular medication. Not suitable at supplemental doses in pregnancy.