You’ve probably heard a lot about the health benefits of drinking tea, especially green tea. Green tea has been shown to play a large role in anti-aging. It can reduce your risk of developing Alzheimer’s, can help build bone density and ward off eye diseases that are common with aging.
Beverage for Anti-Aging
Black, green and oolong teas come from the Camellia sinensis plant. Green tea consists of leaves that haven’t been fermented and so contain the highest level of antioxidants. These teas contain polyphenols. Catechins are the type of polyphenols that seem to have the most potent antioxidant effects, according to Natural Standard, the leading and most-respected reviewer of herbal compounds.
The Mayo Clinic summarized some of the findings about green tea in 2008. Epidemiological or population studies seem to suggest that drinking tea may:
- Reduce atherosclerosis and risk of heart disease
- Lower blood pressure
- Reduce cholesterol levels
- Reduce inflammation in arthritis cases
- Improve bone density
- Improve memory
- Prevent cancer
The problem with population studies, says Mayo, is that they are not clinical studies: life factors and habits are not controlled, so it may be a combination of lifestyle components that could account for the health benefits in peoples that drink tea.
But other studies have found a great number of health benefits from green tea, especially as it relates to anti-aging.
In 2004, scientists at the University of Newcastle studied the effects of black and green tea on Alzheimer’s disease.
In laboratory studies, both teas prevented the breakdown of acetylcholine, the neurotransmitter strongly linked with memory. The teas also inhibited an enzyme known as BuChE. This enzyme is found in the protein deposits found in the brain of Alzheimer’s patients. The teas were found to inhibit another enzyme, beta-secretase, which is also involved in the protein deposits associated with Alzheimer’s disease.
Japanese researchers published a study on green tea and its effect on the beta-amyloid protein plaques found in Alzheimer’s disease in the April, 2008 issue of the Journal of Nutritional Biochemistry.
The protein plaques associated with Alzheimer’s disease increase brain cell damage and death due to oxidative stress. The researchers found that green tea catechins reduced the level of damaging free radicals in the brains of rats. The green-tea rodents showed much less plaque-induced deficits in memory than rodents that didn’t receive green tea and those that were infused with beta-amyloid proteins.
The scientists extrapolated that a human would need to drink about three liters of liquid infused with 0.5% of the catechins to get similar effects but add that because humans ingest other antioxidants in the form of vitamins and plant polyphenols; it’s likely that a much lower quantity could be effective in protecting memory.
Green tea contains more than four times the catechins that black tea does.
Scientists have also discovered that the antioxidants flavonoids may also protect the brain from oxidative stress.
In 2007, Salk Institute researchers found that the flavonoid epicatechin, found in blueberries, cocoa, grapes and tea, improved memory ability in mice. The researchers found that epicatechin seemed to promote blood vessel growth in the brain.
In 2009, King’s College researchers found that epicatechin may protect brain cells through mechanisms unrelated to its antioxidant ability. Epicatechin is one of the few flavonoids that can cross the blood-brain barrier and the King’s College researchers have found that it somehow protects brain cells from the negative effects of beta-amyloid plaques.
University of Hong Kong researchers published a study in the August, 2009 Journal of Agricultural and Food Chemistry concerning green tea and bone health.
When the bone cells of rats were exposed to green tea catechins; EGC, in particular, stimulated an enzyme that promotes bone growth by 79%. The catechins also increased bone mineralization and weakened the activity of cells that reabsorb bone rather than form it.
Hong Kong scientists teamed up with those from Wales to study the effects of catechins on eye diseases in a study published in the February, 2010 issue of the Journal of Agricultural and Food Chemistry.
The scientists proved that catechins can pass from the digestive tract of rodents to the tissues of the eye and reduced oxidative stress for up to 20 hours after ingestion.
Natural Standard (2008)