Catechins– a family of naturally taking place plant-based chemicals– get the majority of the credit for the reputed health benefits of green tea and a few other Camellia sinensis teas. Although many phytochemicals have some degree of antioxidant properties, catechins seem especially potent in battling the totally free radicals widely believed to cause disease and cell degeneration. If you’re not a tea drinker, you can get your catechins in a handful of other plant-based foods.
Pinpointing the place of catechins in the general plan of phytochemicals– chemical compounds found throughout the plant world– can be a bit confusing. Biochemists categorize catechins as flavanols, which, like the carefully associated flavonols, are plant pigments with medical properties.
Flavanols are a subfamily of flavonoids, which are polyphenols that fall under the wider classification of phenolic substances. In addition to catechin itself, the catechin clan has 5 other primary members: epicatechin, gallocatechin, epigallocatechin, epicatechin gallate and epigallocatechin gallate, or EGCG. Although similar in chemical structure, the catechin member of the family have slightly varying properties and strengths.
Catechins in Green Tea
Largely responsible for the favorable health buzz surrounding green tea, along with the rather bitter taste of the drink, catechins appear in other ranges of tea brewed from the dried leaves of the Camellia sinensis plant. Nevertheless, unlike black tea, green tea is made with the unfermented leaves of the plant, which represents its higher share of the antioxidant polyphenols referred to as catechins.
Green tea consists of the complete enhance of catechins, consisting of EGCG, which is the most active polyphenol in the beverage. Preliminary studies indicate that catechin-rich green tea might have a function in treating a wide variety of ills, consisting of high cholesterol, particular cancers, liver disease, diabetes and inflammatory bowel disease.
Data from the University of California Davis indicate that 100 grams of brewed green tea include 2.6 milligrams of catechin, 8.3 milligrams of epicatechin and 114.3 milligrams of epigallocatechin, epicatechin gallate and EGCG. The same quantity of brewed black tea includes 1.5 milligrams of catechin, 2.1 milligrams of epicatechin and 23.1 milligrams of epigallocatechin, epicatechin gallate and EGCG.
Green Tea Composition
About 30% of the leaves by weight are either favonols or flavanols, the latter which is comprised mostly of substances called catechins. These catechins are then broken down into four primary categories of: epigallocatechin-3-gallate (EGCG), epi-gallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC). Although all catechins share comparable properties, EGCG seems most potent in regards to much of them. These 4 catechins are the primary catechins, although some other isomers or conjugates may exist (with either catechin or epicatechin as a backbone, and varying levels of gallic acids).
Typical sources of catechins in green tea (mostly the 4 specified) include:
- Tea from the leaves of Camellia Sinensis, used to prepare White, Green, Oolong, and Black teas.
- Korean fermented tea which has lower amounts of catechins but a higher anti-oxidant capacity.
Digestive tract uptake (bioavailability) of green tea catechins is low, ranging from 1.68% in humans (comparable in rats to approximately 13-26.5% in mice. This low intake is partly due to the physical structure of catechins (due to being a hydroxylated polyphenols) which form a big hydration shell; they are soaked up by means of passive diffusion (in between digestive tract cells) instead of via a transporter. Catechin absorption is improved on an empty stomach for both pure EGCG and a decaffeinated green tea extract including multiple catechins.
There is likewise a fairly big degree of instant efflux due to quick metabolic process by glucuronidation enzymes (UGTs) adding to this low bioavailability (mice), and preventing these enzymes with piperine (from black pepper) appears to increase absorption of EGCG; while an increase in bioavailability was not calculated in this study, both AUC (20-30%) and Cmax (10%) are increased while fecal EGCG indicative of malabsorption reduced to half or less.
Catechins in green tea, especially EGCG, appear to be improperly absorbed in the intestines primarily due to there not being a transporter that takes them up from the gut into the body. They are much better soaked up on an empty stomach. Absorption might be able to be increased with piperine, however research studies have to be performed in rats or people (since the animals used, mice, show interspecies distinctions when compared with people).
Catechins in green tea, primarily EGCG, are inhibitors of digestive sulfurotransferase enzymes which might metabolize other supplements or drugs. This property is shown flavonoids found in green tea like Quercetin. The repressive capacity on this enzyme can likewise extend to the colon, and apply anti-carcinogenic impacts on colonic growth cells through inhibiting the metabolism of some procarcinogens.
Heart disease, consisting of heart disease and stroke, are the most significant causes of death in the world. Research studies show that green tea can enhance some of the primary risk factors for these illness. This consists of total cholesterol, LDL cholesterol and triglycerides.
Green tea also dramatically increases the antioxidant capability of the blood, which secures the LDL cholesterol particles from oxidation, which is one part of the path towards heart disease. Offered the helpful results on risk factors, it is not surprising to see that green tea drinkers have up to a 31% lower risk of cardiovascular disease.
Green tea has actually been shown to lower overall and LDL cholesterol, as well as protect the LDL particles from oxidation. Observational research studies show that green tea drinkers have a lower risk of cardiovascular disease.
Considered that green tea can boost the metabolic rate in the short-term, it makes good sense that it might help you drop weight. Numerous research studies show that green tea causes reductions in body fat, specifically in the abdominal area. Among these studies was a randomized regulated trial in 240 males and females that went on for 12 weeks. In this study, the green tea group had considerable reductions in body fat portion, body weight, waist circumference and abdominal fat.
However, some studies do not show a statistically substantial increases in weight loss with green tea, so this has to be taken with a grain of salt. Some studies show that green tea results in increased weight loss. It is especially effective at reducing the unsafe abdominal fat.
However, given that green tea drinkers are at a lower risk of heart disease and cancer, it makes sense that it might help you live longer. In a study of 40,530 Japanese adults, those who drank the most green tea (5 or more cups each day) were substantially less most likely to die during an 11 year period:
- Death of all causes: 23% lower in women, 12% lower in men.
- Death from heart disease: 31% lower in women, 22% lower in men.
- Death from stroke: 42% lower in women, 35% lower in men.
Another study in 14,001 senior Japanese people aged 65-84 years discovered that those who consumed the most green tea were 76% less likely to pass away during the 6 year study period.
It has been postulated that for green tea catechins to be effective as an anti-cancer representative (through one mechanism), a dose of over 100uM would be needed in the interstital fluid at any given time. This is based off of two in vitro research studies on tNOX showing stated concentration being where results on cancer growth are first kept in mind.
Catechins in green tea can influence cancer metabolism in a multitude of methods. Through telomerase inhibition, inhibiting topoisomerases, tNOX inhibition, selective inhibition of COX2 enzymes without affecting COX1, induction of cellular apoptosis and guideline, and possibly inhibition of BCL-2 proteins.
Green Tea Catechins Side Effects
In investigating toxicity of green tea in animals, administration of either Teavigo or Polyphenon E (two brands of green tea catechins) leads to dose-dependent toxicity connected with vomiting and diarrhea, resulting in death, in beagle dogs fed excessive doses (higher than 500mg/kg); beagle dogs were used due to having better absorption rates of green tea catechins from the intestines.
Vomiting may be related to gastric damage, and 2000mg/kg oral administration to rats causes 90% lethality associated with hemorrhaggic sores in the stomach and intestinal tracts. Remarkably, animals with lower absorption rates of EGCG from the intestinal tracts suffer higher intestinal tract damange and less systemic (liver and kidneys).
In the beagle dogs, toxicity to the liver was confirmed with elevated ALT and with female dogs suffering liver necrosis; other research studies injecting green tea extract (150mg/kg) likewise note boosts in ALT and liver toxicity with extreme dosages. Proximal tubule necrosis (kidneys) was noted at the oral dosages in dogs.
Extreme levels of green tea catechins (mostly EGCG) have been verified for toxicity, primarily in the intestinal tracts, stomach, and liver with extreme levels in the blood possibly harming the kidneys also. Queasiness from green tea supplements is not naturally connected to stomach damage.
Although green tea provides the best variety of catechins per serving, cocoa products likewise consist of a modest amount of these antioxidant-rich polyphenols. Inning accordance with UC Davis, 100 grams of cocoa include 26.2 milligrams of epicatechin. An equivalent quantity of dark chocolate has 12 milligrams of catechin and 41.5 milligrams of epicatechin, while 100 grams of milk chocolate contain 2.1 milligrams of catechin and 6.3 milligrams of epicatechin.
Catechins in Fruit
Closely related to tannins, another class of polyphenols, catechins take place naturally in the skins and seeds of specific fruits. UC Davis data show that black grapes include 10.1 milligrams of catechin, 8.7 milligrams of epicatechin and 2.8 milligrams of epigallocatechin, epicatechin gallate and EGCG per 100-gram serving.
Blackberries have 37.1 milligrams of catechin, 4.7 milligrams of epicatechin and 0.8 milligrams of epigallocatechin, epicatechin gallate and EGCG per 100-gram serving. It too includes catechins, as do apples, cherries, pears and raspberries in smaller quantities.
Good luck! Have a nice weekend.