A new research finding, reported in the Journalof Nutritional Biochemistry is that green tea may strengthen guthealth and protect against obesity.
The study was carried out at the Ohio State University and examinedthe impacts of green tea consumption on two groups of male mice. One was fed a high-fatdiet over an 8-week period that intentionally led to obesity. The other groupwas given a regular diet. (Female mice were excluded because of their knownresistance to diet-induced obesity.) Green tea extract was mixed into thefood of half of each group. At the end of the two months, the research teamexamined (1) body and fat tissue, (2) evidence of leaky guts, inflammation infat tissue and intestines and (3) the composition of gut microbes.
Theresults were striking. Mice given the high-fat diet supplemented by the greentea extract gained 20 percent less weight than those fed with just theobesity-inducing high-fat regimen. There was the same though less markedeffect on the mice put on the regular diet supplemented with green tea. Othermeasures showed that the green tea supplement produced healthy bacteria forboth diets: low resistance to insulin and less intestinal inflammation.
The obvious limitation on drawing conclusions from this studyis that while mice are close to humans in their genetic, biological andbehavioral characteristics, they are not identical and results from rodentstudies – 95 percent of all subjects in medical testing – may not transfer tohumans.
More consequentially, many reporters interpret the results asshowing that green tea really does improve gutleakage. That is not scientifically grounded. Leakage is thepostulated but unproven claim that the intestines’ protective wall can lose itsimpermeability and develop microholes. This gut leakage is seen as a genericillness by many nutritionists and a syndrome associated with bloating, gas,food sensitivities and cramps. Physicians are more likely to regard it as ahoax, euphemism for hypochondria, or a signal of some other illness needingdiagnosis. More recently, there seems to be a shift towards consensus. Here’sthe conclusion of the director of one of the leading nutrition clinics in theUS: “We know that [leakage] exists… In the absence of evidence, we don’t knowwhat it means or what therapies can directly address it.”
Thehuman gut is extraordinarily complex and even the advanced technology ofmolecular biology has been unable to decipher its dynamics. Here are a few figures:
Small intestine, average length 23 feet. Large intestine: 5 feet
Bacteria: 40 trillion,mostly beneficial in stimulating vitamin formation, control of which nutrientsand microorganisms get into the bloodstream, but also associated with manyillnesses, including colon cancer, celiac and diabetes.
Estimates of bacterial species diversity: 1,000 to 40,000.
Gut bacteria reported as newly discovered in February 2019: 2,000.
Richard Bruno, the leader of the research team is cautiousin his conclusion:“This study provides evidence that green tea encourages the growth of good gutbacteria, and that leads to a series of benefits that significantly lower therisk of obesity,” He stresses the need for human studies and evaluation ofdosages and formulations of potential drug therapies. That’s a strong “may”assessment” but just that.
He is much more emphatic in his hopes and expectations:“Two-thirds of American adults are overweight or obese and we know that justtelling people to eat less and exercise more isn’t working. It’s essential todevelop complementary health-promoting approaches…” He informally estimatesthat drinking enough tea to provide the equivalent amount for humans of the teaextract would require cups a day.
The study is a first-rate design and it shows that green teadoes affect obesity. It seems likely to have comparable impacts on humans.
Sources: Science Daily, WebMD, Harvard Health Publishing
CAPTION: Mice given green tea with high-fat diet gained 20percent less weight than those fed with just the obesity-inducing high-fatregimen.