The perennial plant mat? or yerba mat? (Ilex paraguariensis) is a native tree of South America, the leaves of which are widely consumed as a hot beverage in South America and the Middle East. Despite failed attempts in the past decade to get North Americans to develop a taste for this brewed beverage, it now appears to be gaining acceptance as an ingredient in solid dosage forms positioned as a weight-loss agent.
Mat? harbours appreciable amounts of caffeine, partly explaining its popularity as a component of hot beverages such as chimarr?o and the iced version, terer?. However, the caffeine content in mat? is notably less than in its northern cousin from Costa Rica—coffee.
Studies Speed Use
A recent paper that analysed the caffeine content of 14 different commercial mat? products found a range of 0.3?1.72 per cent.1 When three of these products were subjected to infusions at different temperatures and particle sizes, the caffeine content ranged from 0.9?1.58 per cent. The wide range of caffeine content likely results from both the geographic region of the starting leaf biomass and the sequential blanching and drying steps involved in processing.2,3
Interest in mat? heated up after a randomised, controlled trial showed a combination of encapsulated extracts of yerba mat? leaves, leaves of Turnera diffusa Willd. ex Schult. var. aphrodisiaca (damiana) leaf, and guaran? (Paullinia cupana) seeds (another source of caffeine) produced weight loss.4 The ?YGD? composition provided 112, 95, and 36mg of the mat?, guaran? and damiana extracts, respectively.
In the study, 44 men and women who were mildly to moderately overweight took either three capsules of YGD or placebo with a tall glass of water 15 minutes before each main meal. A different group of 47 mild to moderately overweight subjects took either YGD or placebo for 45 days. Lastly, 24 YGD subjects (those who lost a minimum of 3.6kg from the 45-day study) continued using the product for 12 months.
In the ten-day study, the YGD group lost an average .8kg compared with the 0.3kg lost with placebo. After the 45-day study the YGD group showed an average drop in body weight of 5.1kg, compared with 0.3kg in the placebo group. In those who continued taking YGD for one year, no additional weight loss nor weight regain was observed.
The authors of this paper observed a significant (average of 53 per cent) slowing of gastric emptying (and consequent sensation of fullness) after ingestion of 400mL apple juice among seven people who received either three YGD or placebo caps. This appears to be the only systematic clinical trial supporting any weight-loss efficacy related to yerba mat? consumption, despite yerba mat? alone not being evaluated.
Epidemiological evidence suggests that mat? consumption, as a hot beverage, is associated with an increased risk for regional cancers, particularly oral, oropharyngeal and esophageal cancers, even after adjusting for alcohol intake and smoking.5,6
In contrast, a recent study found a boiling water extract of dried plant/stems of yerba mat? (and alpha-tocopherol) protected yeast cells from hydrogen peroxide-induced DNA damage and cell death, apparently via an antioxidant mechanism. Alternately, hyperthermic irritation (from a very hot beverage) has been proposed as mediating the carcinogenic effects of mat?.7 To date, no animal carcinogenicity studies appear to have been conducted. Clearly, more work on this botanical is warranted.
1. Pomilio AB, et al. High-performance capillary electrophoresis analysis of mat? infusions prepared from stems and leaves of Ilex paraguariensis using automated micellar electrokinetic capillary chromatography. Phytochem Anal 2002;13:235-41.
2. Gauer L, Cavalli-Molina S. Genetic variation in natural populations of mat? (Ilex paraguariensis A. St.-Hil., Aquifoliaceae) using RAPD markers. Heredity 2000;84:647-56.
3. Schmalko ME, Alzamora SM. Color, chlorophyll, caffeine, and water content during yerba mat? processing. Drying Tech 2001;19:599-610.
4. Andersen T, Fogh J. Weight loss and delayed gastric emptying following a South American herbal preparation in overweight patients. J Hum Nutr Dietet 2001;14:243-50.
5. Goldenberg D, et al. The beverage mate: a risk for cancer of the head and neck. Head Neck 2003;25:595-601.
6. Putz A, et al. TP53 mutation pattern of esophageal squamous cell carcinomas in a high risk area (southern Brazil). Int J Cancer 2002;98:99-105.
7. Bracesco N, et al. Antioxidant activity of a botanical extract preparation of Ilex paraguariensis. J Altern Complem Med 2003;9:379-87.