Like black and green tea, rooibos is rich in polyphenols, such as rutin and quercetin. Cell and animal studies, mostly from South Africa, have shown that rooibos extracts have antioxidant, immune-stimulating, and anti-cancer properties. But studies of rooibos tea in people are limited. There’s little or no evidence to back claims that it relieves constipation, headaches, eczema, asthma, insomnia, high blood pressure, mild depression, ulcers, diabetes, and so on.
Stone ground: Instead of being rolled, shaped, and dried like traditional green tea leaves, the leaves destined for matcha are laid flat to dry and become tencha, the leaves from which matcha is made. The tencha leaves are then stripped of their stems and veins. The remaining leaf material is ground in slow-turning stone mills, yielding a smooth green tea powder.
This tea is a rich source of antispasmodic agents, which can ease severe stomach cramps and abdominal pains. This is mainly due to the activation of K+ (potassium) ions in the body without antagonizing the activities of calcium, according to a report published in the Basic & Clinical Pharmacology & Toxicology. This can reduce the presence of hyperactivity in the gastrointestinal tract, thus preventing diarrhea and other intestinal issues.
Green tea contains significant amounts of flavonoids, antioxidants that protect against heart disease by slowing the breakdown of LDL cholesterol, preventing blood clots, and improving blood vessel function. The benefits of green tea also include associations with lower cholesterol and lower rates of artery blockages. People who drink a cup or two a day have a 46 percent lower risk of developing narrowed arteries. Upping that to three cups a day lowers the risk of having a heart attack by 43 percent and of dying from a heart attack by 70 percent. It can even help prevent a second heart attack. In a study of 1,900 patients recovering from heart attacks at Beth Israel Deaconess Medical Center in Boston, the death rate among patients who drank at least two cups of tea a day was 44 percent lower than among non-tea drinkers.
According to the National Cancer Institute, the polyphenols in tea have been shown to decrease tumor growth in both animal and laboratory studies. Researchers believe that it is the high level of polyphenols in tea that help kill cancerous cells and stop them from growing, although the exact mechanism by which tea inhibits and prevents cancerous cells is uncertain.
Another big draw health benefit-wise is that matcha, like green tea, is loaded with antioxidants. A study, published in 2014, found the plant also had antimicrobial properties, particularly the four types of catechins (antioxidant properties flavonoids) it contains, against a few different types of microorganisms. Yet another study, published in Nature, proved that catechins inhibit the growth of a bacteria called Fusobacterium nucleatum — the bacteria that causes cavities and periodontal disease.
Sejak (세작; 細雀; lit. "thin sparrow"), or dumul-cha (두물차; lit. "second flush tea"), is made of hand-picked leaves plucked after gogu (20–21 April) but before ipha (5–6 May). The tea is also called jakseol (작설; 雀舌; lit. "sparrow tongue") as the tea leaves are plucked when they are about the size of a sparrow's tongue. The ideal steeping temperature for sejak tea is 60–70 °C (140–158 °F).
Dulloo, Abdul G., Claudette Duret, Dorothée Rohrer, Lucien Girardier, Nouri Mensi, Marc Fathi, Philippe Chantre, and Jacques Vandermander. “Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans.” The American journal of clinical nutrition 70, no. 6 (1999): 1040-1045.
Unlike traditional green tea, matcha preparation involves covering the tea plants with shade cloths before they’re harvested. This triggers the growth of leaves with better flavor and texture, which are hand selected, steamed briefly to stop fermentation, then dried and aged in cold storage, which deepens the flavor. The dried leaves are then stone-ground into a fine powder.
Rooibos tea is anti-inflammatory in nature, which means that it reduces blood pressure and scavenges free radicals like other antioxidants. Quercetin, another powerful antioxidant found in rooibos tea, has been linked to preventing a wide variety of heart conditions. It promotes an increase in HDL cholesterol (good cholesterol) and inhibits the LDL cholesterol (bad cholesterol) from binding to the walls of arteries and blood vessels.