Flavonoids, a Variety of Polyphenols, Keep the Heart Younger

21/03/08 A polyphenols-rich diet keeps the heart younger. This finding comes out from a study by the University of Grenoble in collaboration with the other Centres participating to the FLORA Project, a European Commission funded research studying the effects of flavonoids, a variety of polyphenols, on human health.

The scientific work, published in the Journal of Nutrition, is one of the few approaching this field by in vivo studies. "So far- says Marie-Claire Toufektsian, leading author of the study- the biological and protective activities of various flavonoids have been extensively studied in vitro, on cell- based assays. Nevertheless, this kind of approach has a major limitation: it is extremely difficult to assess precisely the nature of all flavonoids absorbed following consumption of plants present in a given meal. In other words, laboratory cultured cells alone are not sufficient to study a complex mechanism such as that of absorption of food flavonoids". That is why we need to turn attention on other features. The most obvious solution appeared to be to study the effects of this kind of polyphenols on experimental animals. The turning point started from plants: those rich in flavonoids made the case of researchers.

Toufektsian used two kinds of corn: one anthocyanin-free (anthocyanins is a variety of flavonoids) and the other, obtained by the Department of Biomolecular Sciences and Biotechnology of University of Milan through traditional cultivation techniques with no transgenic modifications, rich in anthocyanins. "The corn seeds were introduced into a rodent food formula in order to obtain two groups of rats following two different kinds of diet for a couple of months" says Chiara Tonelli, head of the Milan group. In the meantime researchers accurately measured the anthocyanins levels in urine and plasma samples from the two groups of rats by using a method developed by the Research Laboratories at the Catholic University of Campobasso. Then researchers studied the onset and evolution of myocardial infarction induced experimentally in both groups.

"We found - Toufektsian adds - that chronic consumption and effective absorption of anthocyanins rendered the rats more resistant to myocardial infarction; in other words, the size of the infarct was significantly reduced in rats fed the anthocyanin-rich diet".

The quantity of absorbed anthocyanins is important too. Maria Benedetta Donati, scientific coordinator of the Research Laboratories of Campobasso, argues that "the rats fed the anthocyanin- rich diet received about 13- fold more anthocyanins than most people following a standard Western-type diet, where the daily consumption of flavonoids is relatively low and the average intake of anthocyanins is estimated to be only 12 mg per day".

The Authors turned their attention on Mediterranean diet stressing the crucial difference between this kind of diet and the so called Western Diet, that is rich in fats and poor in fibres. "The anthocyanins content of the traditional Mediterranean diet is much higher than that of the Western Diet, which might explain why the Mediterranean diet is cardioprotective" says Michel de Lorgeril, cardiologist, head of the Grenoble group.

However promising these results appear to be, researchers go easy on them. "The cellular mechanisms of the protection are not clearly determined yet- Toufektsian warns- Moreover, there may be differences between humans and rats, for example in terms of flavonoid absorption and metabolism".

Human volunteers are the target of another phase of the FLORA Project. The Research Laboratories of the Catholic University of Campobasso are studying the process of absorption and metabolism of anthocyanins from blood orange juice- one of the most generous sources of flavonoids- in human body. In this way researchers aim at evaluating how these compounds are absorbed by human body to play their beneficial effects.