Wetenschap - 21 juni 2016

Healthy substance in tea identified

tekst:
Anja Janssen

It has been known for some time that tea provides protection against cardiovascular diseases, but not exactly which substance is responsible for this. James Dower and his colleagues at Human Nutrition have come up with findings that make the flavan-3-0l epicatechin a strong candidate. They published their findings in the American Journal of Clinical Nutrition.

According to the researchers, they have shown for the first time that there are fewer deaths from heart attacks or another coronary heart disease among older men who get a lot of epicatechin from their diets than among men who get little of the substance. For cardiovascular diseases in general, the link between a higher intake and a lower risk of death was only significant if the men already suffered from these diseases.

The researchers divided the men into three groups on the basis of their intake of epicatechin. The risk of death was 38 percent lower in men with the highest intake (22 mg/day) than in men who got very little (8 mg/day). In patients the risk of death by cardiovascular diseases went down by 46 percent.

‘We cannot yet claim, however, that epicatechin protects against cardiovascular diseases,’ says co-author Peter Hollman. ‘Because we based our study on epidemiological data, and they only show a causal effect by very strong effects. Clinical trials must be done first with pure epicatechin.’

The epidemiological data in the Wageningen study came from 744 older men who were monitored for 25 years in the Zutphen Elderly Study. Statistical analysis was aimed at clarifying whether it is only the epicatechin in tea which may have a protective effect, or epicatechin from other sources too, such as apples and cocoa. Hollman: ‘The link found became stronger when we took epicatechin from all sources. That indicates that it is the epicatechin that does the trick.’

The focus on just one isolated substance goes against the holistic trend in dietary advice, however. ‘It is great of course to know that tea has an effect, but you are interested in mechanisms as well,’ Hollman reacts. In terms of mechanism, clinical trials have shown that tea increases the flexibility of blood vessels and lowers blood pressure – effects which lower the risk of cardiovascular diseases.

the publication


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