Yerba mate contains many substances, the most important of which are the purine alkaloids (caffeine, theobromine), polyphenols (chlorogenic acid), saponins, minerals and vitamins (A, B1, B2, C, E), falvonoids and 0.3% etheric oil.1,2,3
The amount of active ingredients and minerals in yerba mate changes depending on certain conditions, such as genetic differences between plants. A research document published in 2009 disclosed the results of a study showing the amount of active ingredients in eight genetically different types of yerba plant. All the plants were grown in the same place and their leaves were simultaneously collected for analysis. The biggest difference was evident in relation to the amount of triterpenoid saponins (from 0.003 to 0.080%), caffeine (from 0.226 to 1.377%), theobromine (from 0.176 to 0.831%), a smaller difference was found in relation to chlorogenic acid (from 1.344 to 2.031%).4
The conditions under which the plant is cultivated are of high importance. Too much sunlight (incl. UV rays) might lead to increased production of polyphenols.5 Generally speaking plants which are exposed to less light and grow in stressful conditions (e.g. are under constant insect attack) produce higher amounts of defensive materials such as caffeine6 and polyphenols5 but at the same time plants growing in shade produce more minerals (micro and macro elements).7 Leaves which are protected by caffeine and polyphenols against fungi and insects manage to survive longer on the plant and carry on the process of photosynthesis. In this way they compensate the plant for the biological cost which it bore in producing them. Thus yerba mate plants coming from natural forests may well contain more caffeine than those cultivated on farms. A study carried out in 2007 confirmed that trees growing in shady places have more caffeine, sometimes even twice as much as those growing in full sunlight. The amount of caffeine is also related to nitrate fertilizers used in cultivation. Fertilized plants growing in shade had double and those growing in sunlight had treble the amount of caffeine.2 Other studies showed that yerba mate trees growing on plantation in full sunlight have more polyphenols and caffeine than the trees growing in forests.5,8 However, this particular study did not take into account other variants therefore the reasons for the differences are certain.
Which leaves are harvested and when is of great importance. Young leaves are particularly tempting to insects and therefore need special protection. Thus young leaves, as well as young fruit have higher concentration of caffeine than old leaves and ripe fruit.9 Similarly young leaves have more polyphenols8 and minerals (micro and macro elements)7. The twigs which we find in yerba mate have lesser amounts of polyphenols and caffeine than the leaves1,10. The precise timing of picking the leaves is very important. In the state of Rio Grande do Sul in Brazil the leaves harvested between December and March had on average approximately 0.75% methylxanthines (caffeine, theobromine) while the leaves picked between June and September only had 0.3%11
In 2007 studies on polyphenol and caffeine contents were conducted in Brazil. In each of the three places in the state of Paraná, namely Ivaí, Rio Azul i Guarapuava, trees originating in 4 different Brazilian regions were cultivated. They came from Ivai, Quedas do Iguaçu, Cascavel and Barão de Cotegipe. There were significant differences in caffeine and theobromine levels in yerba plants coming from these different regions (the caffeine levels varying from 0.489 to 0.611%) but also in those grown in different places (levels from 0.426 to 0.695%)12.
Of the greatest interest to all those who drink yerba mate is the study from 2008 in which 15 different types of yerba mate, coming directly from producers in Argentina, Paragway and Brazil were compared. They included mate from plantation and from natural forests.Table 1. Differences between the composition of yerba coming from trees from plantations and trees from forests (in milligrams per gram of dried leaves)5
|Forest||3.9 – 12.1||1.5 – 3.8||100.3 – 154.6||20.9 – 54.4||4.8 – 16.6||2.6 – 5.6|
|Plantation||7.5 – 16.7||2.7 – 7.6||102.7 – 179.7||32.3 – 80.5||10.3 – 24.9||4.3 – 11.5|
In general, plantation products had more polyphenols and caffeine on average than the forest products although there were differences in the levels of those substances within both groups. In branded yerba mate products there are more differences in caffeine levels than there are in polyphenol levels.
Phenol compounds have antioxidant and anti-mutagenic properties, both of which are of great importance in the prevention of cancer, stroke and certain chronic diseases such as diseases of the circulatory system.13
Dried leaves of yerba mate contain circa 10% polyphenols, mainly chlorogenic acid and its isomers. They also have caffeic acid, quinic acid, caffeoyl glucose and feruloylquinic acid. Other ingredients of yerba mate are flavonoids (0.064%), namely rutin, quercitrin and kaempferol.14,15,16,17
Polyphenol compounds present in yerba mate are significantly different from those in green tea as yerba mate is rich in chlorogenic acids and does not contain catechins.18Table 2. Polyphenols in green tea, black tea, and yerba mate1
|Polyphenols||Green tea||Black tea||Yerba mate|
The highest concentration of polyphenols was found in the extract of shredded leaves. The lowest level in yerba mate was reached in mixtures with more twigs, mixtures poorly ground or mixtures of different type of yerba mate10. Other species of Holly (Ilex) genus (I. argentina, I. brevicuspis, I. theezans, I. dumosa var dumosa, I. pseudobuxus) also contain polyphenols and antioxidants but Yerba Mate (I. paraguariensis), has the highest content of polyphenols and significantly stronger antioxidant properties.19
Yerba mate has three purine alcaloids: caffeine, theobromine and theophylline. Only some studies confirm the presence of theophylline and they show that the amounts are negligible.20Table 3. Levels of caffeine, theobromine and theophylline in dried leaves of yerba mate (Ilex paraguariensis)5,13,20,21,22
|Average||0.4 - 1.7%||0.15 - 0.76%||Traces|
The two most important compounds, caffeine and theobromine, are found mainly in the plant leaves but small amounts are also found in the wooded stems which are often found in yerba mate products.1
Analysis showed that 500 ml of yerba mate prepared in accordance with the Brazilian tradition (chimarrão) had a caffeine content of 260 mg. The chimarrão was prepared in a small 250 ml cuia gourd which had 25-30 g of yerba mate and was filled twice with hot water at 85 degrees centigrade (185 °F).23
Some sources state that yerba mate contains mateine, which is a stereoisomer of caffeine, which would make it a different substance. This is erroneous because caffeine is an achiral molecule which by definition cannot contain any optical isomers, incl. enantiomers. In other words, mateine, like theine in tea, is a synonym for caffeine.24
Effects of caffeine:
Caffeine stimulates the cortex of the brain, dilates the coronary arteries and the meningeal arteries, stimulates heart action and the secretion of gastric acid and is a diuretic. It stimulates the body and acts as an analgesic. It might cause blood pressure increase.25
Effects of theobromine:
Theorbomine has a relaxant effect on the smooth muscle tissue of the circulatory system and causes an increase of blood flow through the kidneys and the filtration through the capillaries of the kidney glomerulus. It is sometimes used as a diuretic, or in treatment of high blood pressure and circulation problems.25
Saponins are bitter substances which are soluble in water. They affect the taste of yerba mate.1 Saponins are responsible for the medicinal properties of many health plants. For example, they are the main active ingredient of ginseng.26 The leaves of yerba mate contain 1.2% saponins, mainly matesaponins 1 i matesaponins 227Table 4. Saponins in yerba mate (Ilex paraguariensis)27
in mg per one g of dried leaves
Matesaponins have been shown to have anti-inflammatory properties in vitro.28
They minimize the growth and induce apoptosis (death) of colon cancer in vitro.27
The infusion of yerba mate is particularly rich in potassium, magnesium and manganese, is reasonably rich in sulphur, calcium and phosphorus, but contains no cadmium or lead29 although some tests have shown minimal and acceptable amounts of lead in the commercially available yerba mate.
The solubility of minerals in the infusion is dependent on the amount of tannin present in it. The lower the concentration of tannin, the better the solubility of all minerals apart from nickel.1
The potassium present in yerba mate might assist with lowering blood pressure. In many tests published in the early 1990s it was shown that oral intake of potassium leads to the lowering of blood pressure, especially in people with hypotension (systolic pressure was lowered by 8.2 mm HG on average and diastolic pressure by 4.5 mm Hg).30Table 5. Minerals present in yerba mate (Ilex paraguariensis).29
|Element||Dry yerba mate