In a study published in the Journal of Nutrition and Intermediary Metabolism, it was found that tea, particularly its green and black varieties, can lower blood sugar and prevent fat storage in the liver.
The research team, which was from the University of Tunis El Manar and the University of Carthage in Tunisia and Université Paris Diderot in Paris, sought to determine the effects of long-term consumption of black and green tea on the lipid digestion of rats fed with high-fat diet. Green tea decoctions, black tea decoctions or a placebo for 10 weeks were given in the rats. They measured the liver fat content, food intake, fat excreted in feces, the weight of abdominal fat tissues, and the body weight gain.
The major polyphenolic compounds found in the black tea decoction were catechin, EGCG, kaempferols, gallic acid esters, theaflavins, gentissic acid esters, caffeine, and quercetin. While a 15-minute decoction of green tea was found to have polyphenolic compounds which include epigallocatechin (EGC), catechin, kaempferol 3-glycoside, caffeine, epigallocatechin gallate (EGCG), epicatechin gallate ECG, EGC-3-methyl gallate, and vanillic acid ester.
The results show that when green tea and black tea is consumed for 10 weeks, it can increase fecal lipids and triglycerides excretion thereby decreasing lipid digestion. Aside from this, there was also a reduction in the adipose tissue gains which is in line with the reduction of circulating leptin levels. Moreover, body weight gains of rats fed with high-fat diet were decreased. However, it was found that black tea is more effective than green tea.
The research team wrote like this:
“Therefore, these beverages containing high amounts of TPC and caffeine could constitute a natural alternative in the prevention of obesity.”
Green Tea Versus Black Tea
Green tea and black tea are from the same plant called Camellia sinensis but they undergo different processes. As green tea undergoes a minimal process, black tea, on the other hand, undergoes an oxidation process known as fermentation. Though there may be slight differences, both drinks provide many health benefits.
As compared to black tea, green tea has a lot to offer when it comes to anti-cancer properties. Green tea contains high amounts of catechins, such as EGCG, which regulates gene activity in cancer cells and might fight cancer growth.
Both the tea support cardiovascular health. A study published in the Journal of Biological Chemistry discovered that the abundance of EGCG in green tea interacts with the cells lining the blood vessels and promotes autophagy, which is a physiological process that shields the cells from stress.
Researchers also found that it can also regulate blood cholesterol levels. Black tea, on the other hand, was found to improve blood vessel function among people with coronary heart disease, claimed by the Linus Pauling Institute.
There was a difference between the caffeine levels of black and green tea. Green tea contains lower caffeine content with 9 to 50 mg per cup, while black tea contains between 42 to 72 mg per cup. Caffeine temporarily boosts alertness, help in weight loss, and promote productivity. Yet, caffeine consumption should be limited as it can keep a person up at night.