Yerba mate (sometime labeled as mate, or Ilex paraguariensis) is a South American shrub of the holly family. It is commonly used to create a “tea like” infusion called “maté.” Both dried leaves and twigs can be used in the infusion, and it may be served hot or cold.
Of interest to us, however, is yerba mate’s common use in weight loss products. Why is it included, and is there any good reason for it?
Yerba mate contains the xanthine alkaloids caffeine, theobromine, and theophylline—it is these common stimulants that are the most likely reason. After all, caffeine’s positive effects on weight loss is well established (see Am J Clin Nutr. 1989 Jan;49(1):44-50, Am J Clin Nutr. 1980 May;33(5):989-97).
Yerba mate is a decent source of caffeine, and although strength and potency varies, it provides about half the caffeine of coffee.
Theobromine and theophylline are also stimulants, although they have a lesser effect on the central nervous system (CNS) than caffeine.
Yerba mate is also a source of chlorogenic acid, a compound which may demonstrate some weight loss benefits. Research, however, is in the preliminary stages, and has only been performed on animals to date (see BMC Complementary and Alternative Medicine 2006, 6:9).
Despite this, studies showing yerba mate to be an effective weight loss agent have been inconclusive. In one study, yerba mate combined with guarana and damiana resulted in delayed gastric emptying and an increased feeling of satiety (see J Hum Nutr Diet. 2001 Jun;14(3):243-50).
One animal study showed that it reduced the obesity incurred by a high fat diet (Arch Biochem Biophys. 2008 Feb 26).
On the other hand, this study (Am J Clin Nutr. 2004 Apr;79(4):529-36), which examined the clinical evidence for several “natural” weight loss aids — including yerba mate — concluded…
“The evidence for most dietary supplements as aids in reducing body weight is not convincing. None of the reviewed dietary supplements can be recommended for over-the-counter use.”
In lieu of this data, and based on the fact that yerba mate displays powerful antioxidant properties as well, I would not shy away from any weight loss product that contains yerba mate in a supportive role.
However, at this time, there is no conclusive evidence that yerba mate provides weight loss benefits beyond those attributable to its caffeine—and possibly chlorogenic acid—content. Any retailer that makes such claims is not doing so on the basis of existing evidence.