Antioxidants in red wine may cut toxic by-products of red meat in the stomach

There may be good news for those who like a glass of red wine with their steak - scientists in Israel have found that polyphenols in red wine could help protect against heart disease and cancers by reducing toxic by-products of fat digestion.

The team led by Joseph Kanner at the Food Science Department of the Volcani Center in Bet Dagan measured the levels of two compounds that result from fat digestion - malondialdehyde (MDA) and hydroperoxides (LOOH) - in the stomach of rats fed red turkey thigh meat with and without red wine concentrate. These fat-digestion by-products are broken down forming free radicals which cause cell death and DNA damage.

The scientists used red turkey meat because of its low concentration of the antioxidant vitamin E, which means turkey is oxidised faster than beef or lamb, producing more MDA and LOOH in the stomach.

The plasma MDA levels of the rats that ate meat rose 50 per cent. But in rats fed meat with red wine concentrate, MDA levels actually fell by an average of 34 per cent. Similarly, the reduction in MDA and LOOH levels in the stomach was three times greater following red meat with red wine concentrate, than without wine. 

Polyphenols in red wine could be preventing MDA entering the bloodstream by forming a complex with it, Kanner suggests. Or they might be inhibiting digestive enzymes involved in the release of the fat digestion by-products. 

Wine with dinner

These findings in rats follow experiments on humans where Kanner’s team also found that MDA and LOOH levels in the urine and plasma of subjects who had eaten red meat with red wine concentrate were maintained rather than increased. However, the latest experiments focus on the effects of polyphenols in rat stomachs. ’To perform such experiments in humans is very difficult,’ says Kanner. ’The research with rats in vivo shows that such reactions could happen also in humans.’

Kanner explains that the absorption of reactive carbonyls, such as MDA, formed when lipids react with oxygen in a process known as lipid peroxidation, could modify low-density lipoproteins, molecules involved in cholesterol transport. This could be a key trigger for the hardening of the walls of arteries. ’The addition of antioxidants could prevent such reactions,’ says Kanner.

Erik Skovenborg, chairman of the Scandinavian Medical Alcohol Board, told Chemistry World that this latest research is a good model and ’should now be applied to other food and drink to discover which polyphenols or combination of them is effective.’

But Roger Corder, chairman of the management committee of the William Harvey Research Foundation, a medical research charity, is sceptical. ’Research like this gives little insight into what happens to an individual consuming red meat and red wine,’ he said. ’This type of work extrapolates too much to human studies.’

Olivia Walker