Have you ever wondered what makes the Mediterranean diet so healthy? The answer, according to scientists, is melatonin, writes Roger Dobson.
The hormone, which is secreted at night by the pineal gland in the brain, has now been found in plants and foods that are central to a diet linked to low levels of cancer, heart disease and many other diseases. Grapes, red wine, tomatoes, olive oil, rice, beer, nuts and seeds have significant levels of the compound.
‘Melatonin present in plant foods may counteract conditions related to cancer, cardiovascular diseases, diabetes, neurological disorders and ageing,’ says Dr Marcello Iriti, of Milan University, who led the study.
Researchers looked at the role of melatonin, a hormone that helps regulate other hormones and maintains the body’s internal 24-hour body clock.
It is also thought to be involved in ageing, to work as an antioxidant to protect against disease, and to have a boosting effect on the immune system.
Women with breast cancer and men with prostate cancer tend to have lower blood levels of the hormone melatonin than those without the disease.
According to the new Italian research, melatonin has been identified in the key parts of the Mediterranean diet including grapes, wine, olive oil, tomatoes and beer. French, Spanish and Italian wines, especially reds, have all been shown to have levels much higher than other alcoholic drinks, such as whisky, gin, vodka and rum. The melatonin is thought to come directly from grapes. Melatonin was also found in olive oil, especially extra virgin, and in purslane, a commonly used salad ingredient in the region.
In tomatoes, the highest levels were in the seeds, where its role may be to help protect the future generations of the plant from disease.
Although beer is drunk worldwide, it is considered a traditional Mediterranean drink, and high levels of the hormone have been found, possibly from the barley content.
Research also shows that consuming melatonin-rich food and drink leads to increased levels of the hormone in the blood.
One, as yet unpublished, study cited by the Italian team showed that blood levels of the hormone increased by 20 per cent one hour after drinking a 100ml glass of red wine. In another study, levels of melatonin and antioxidants rose 45 minutes after drinking a glass of beer.
And in laboratory animals, melatonin levels increased threefold after eating walnuts.