Green tea and memory

SummaryThere are several claimed health benefits of consuming green tea. Most of the claims have only been substantiated in laboratory experiments on animals with evidence lacking in relation to the actual effects in humans. Although the official view in general is negative to any of the claimed benefits, the industry is confident that the lingering public view is still positive.

Green Tea

Green tea health benefits not conclusive (Photo credit: bkajino)

Green tea’s antioxidants, called catechins, scavenge for free radicals that can damage DNA and contribute to disease. In the UK a few years ago, an advertisement for Tetley Green Tea tried to imply that it contained antioxidants with an equal health effect to general exercise. This was rejected by the advertising watchdog as lacking credible proof.

Research about green tea’s health benefits over the years has claimed that it has potential to fight cancer and heart disease, and that it can lower cholesterol, burn fat, prevent diabetes and stroke, and stave off dementia. Pretty impressive stuff.

Now Chinese research published in the scientific journal Molecular Nutrition & Food Research indicates that the common green tea antioxidant epigallocatechin-3 gallate (EGCG) provides benefits to memory and special learning by boosting the production of important neural cells. Professor Yun Bai and his team from the Third Military Medical University in China found that mice fed EGCG had improved learning and memory by improving object recognition and spatial memory.

Because green tea leaves are withered and steamed during processing, not fermented like black and oolong teas, the catechins, especially EGCG, are more concentrated. But there’s still a question of how much green tea you need to drink to reap its potential health benefits and overcome the poor bioavailability of EGCG. Most of the consistent findings about green tea’s health benefits have come out of laboratories and real-world evidence in humans is lacking.

It is clear that most official authorities are dubious about the claimed effects of green tea and human health.

The Food and Drug Administration (FDA) has warned Dr Pepper Snapple Group that their Canada Dry Sparkling Green Tea Ginger Ale improperly claimed to be enhanced with antioxidants. It also warned that Unilever Inc.’s Lipton Green Tea 100% Naturally Decaffeinated made an unauthorised health claim by linking consumption of green tea to reduced cholesterol for people at risk of heart disease. However, qualified health claims are permitted in the USA. When the firm Fleminger tried to promote its green tea as reducing the risk of prostate and breast cancer, the FDA proposed the following qualified claim:

Green tea may reduce the risk of breast or prostate cancer although the FDA has concluded that there is very little scientific evidence for this claim.

This has not yet been accepted by the company.

In the European Union, Article 13 of Regulation (EC) No 1924/2006 prescribes that general health claims should be assessed by the European Commission based on advice from the European Food Safety Authority (EFSA).

In a 2010 opinion, EFSA provided advice in relation to catechins (including EGCG) in green tea and tannins in black tea, and protection of DNA, proteins and lipids from oxidative damage, reduction of acid production in dental plaque, maintenance of bone, decreasing potentially pathogenic intestinal microorganisms, maintenance of vision, maintenance of normal blood pressure and maintenance of normal blood cholesterol concentrations. In a further 2010 opinion, EFSA addressed claims in relation to the contribution of catechin in green tea and maintenance or achievement of a normal body weight, increased beta-oxidation of fatty acids leading to a reduction in body fat mass, and maintenance of normal blood glucose concentrations. In addition, EFSA in a 2011 opinion addressed claims that catechins in green tea or green tea extracts could improve endothelium-dependent vasodilation, maintain normal blood pressure, maintain normal blood glucose concentrations, maintain normal blood LDL cholesterol concentrations, protect the skin from UV induced (including photo oxidative) damage, protect DNA from oxidative damage, protect lipids from oxidative damage, contribute to normal cognitive function, “cardiovascular system”, “invigoration of the body”, decreasing potentially pathogenic gastro-intestinal microorganisms, “immune health” and “mouth”.

EFSA concluded in all cases that no human studies addressed the claimed effects of either catechins or tannins in sufficient detail and that:

EFSA is of the view that on the basis of the data presented a cause and effect relationship could not be established for any claim.

In some cases they pointed out that the claim was general and non-specific and thus didn’t even qualify as a health claim under the legislation.

But even if the science is lacking the industry is still buoyant believing that the general public supports the view that green tea is good for the well-being of the body. I for one feel energised after a cup of green tea.