The question of how much caffeine is in yerba mate tea has been slightly confused by some vendors' claims that maté does not contain caffeine at all (see Does Yerba Mate Contain Caffeine?). But over a dozen papers have been published which examine the caffeine content of yerba maté, many of them published in Spanish or Portugese because a large portion of yerba maté use takes place in South America and Brazil. Some maté tea vendors now provide actual caffeine contents for their products, but others still hold to the spurious and confused view that there is little to no caffeine in the leaves.

Based on the published research, the general rule is that dried yerba mate tea contains around 1% available caffeine (ranging from 0.5-2%) when made into a tea with warm to hot water.

Hot water appears to provide very good solubility for the caffeine and theobromine, although ethanol (alcohol) and super critical carbon dioxide have been investigated for commercial production of extracts. Boiling water reportedly extracts slightly (5-10%) more caffeine than cold or hot water steeping. It is said that boiled maté tea is less pleasant tasting which may be the result of additional materials such as tannins and oils being extracted from the leaves in addition to caffeine. Temperature variations between warm and hot may not affect extraction much as research by Pomilio found that both 30C and 75C water resulted in similar amounts of caffeine.

A research paper in 2002 by Pamilio et al. tested 14 different brands of commercially available maté tea and performed single five minute, stirred, warm (30C) and hot (70C) water steep on each. They found that extractable caffeine levels varied between 0.30% and 1.72% of dried material using this method, with the lowest values in the tea-bag varietes they chose. Theobromine values were between 0.11% to 0.66%. This corresponds to 3 to 17 mg of caffeine and 1 to 7 mg of theobromine per gram of dried mate single-steeped in hot water, with the median amount around 10 mg of caffeine per gram of dried mate (1.03%).

We only reviewed the findings from papers accessible through PubMed that were published after 1996, although many of the original papers on the subject were published in the 1980s. Results appeared consist among the reviewed papers with natural variation accounting for the differences. A paper by Esmerlindro et al from 2004 tries to look at some of the factors that may influence caffeine content by testing leaves grown under partial shade and testing the leaves at 6, 12, 18, and 24 months of growth from the same set of plants. Their findings did not provide any clarity to what accounts for the variation in caffeine content.

Authors	Year	Extraction Method	% Caffeine	% Theobromine
Filip, Lopez, et al	1998	Water, Boiled 20 minutes	1.9	0.48
Pomilio, Trajtemberg, et al	2002	Water, warm & hot, steep 5 minutes	0.3-1.8	0.08-0.66
Saldana MD, Zetzl C, et al	2002	Liquid Carbon Dioxide and Ethanol	0.3-0.6	---
Esmelindro AA, Girardi Jdos S, et al	2004	Liquid Carbon Dioxide	0.1-0.2	0.07-0.15

Percentages of Caffeine and Theobromine from 14 commercial yerba mate products using water extraction. From Pomilio, Trajtemberg, Vitale 2002
Sample	Type	Caffeine (%)	Theobromine (%)	Relative Standard Deviation (RSD %)
Yerba Mate Tagagui	Milled	1.07	0.39	0.9
Yerba Mate Rosamonte	Milled	0.78	0.31	1.2
Yerba Mate Barbara	Milled	0.97	0.38	1.7
Yerba Mate (bulk)	Milled	1.35	0.50	2.1
Yerba Mate (CBSe)	Milled	1.01	0.66	0.8
Yerba Cruz de Malta	Milled	0.99	0.66	1.8
Yerba Nobleza Gaucha	Milled	1.07	0.2	1.7
Yerba Tranquera	Milled	1.05	0.57	1.6
Yerba Sol de Acuario	Organic	1.08	0.4	2.4
Yerba Esq de las Flroes	Organic	1.72	0.17	2.1
Yerba Cruz de Malta	Bags	0.36	0.16	1.6
Yerba Tranquera	Bags	0.30	0.18	2.2
Yerba Bell's	Bags	0.8	0.08	1.1
Yerba Norta	Milled	1.07	0.11	1.3