A new study suggests eating more foods rich in flavonoids - such as blueberries, strawberries, blackberries and citrus fruit - could reduce the risk of erectile dysfunction for middle-aged men by more than a fifth.
Lead researcher Professor Aedin Cassidy, from the UK's University of East Anglia (UEA), and colleagues in the US from the Harvard TH Chan School of Public Health in Boston spearheaded the study into erectile dysfunction - the inability to get or keep an erection firm enough to engage in sexual intercourse.
Previous research has shown that regular exercise may lower men's risk for erectile dysfunction. However, in this latest study, Professor Cassidy and her team suggest that eating more flavonoid-rich foods is as beneficial for erectile dysfunction as walking briskly for up to five hours weekly.
Professor Cassidy said: "We already knew that intake of certain foods high in flavonoids may reduce the risk of conditions including diabetes and cardiovascular disease. This is the first study to look at the association between flavonoids and erectile dysfunction, which affects up to half of all middle-aged and older men."
The researchers analysed population-based data of more than 50,000 middle-aged men. Information was collected on the men's ability to get and maintain an erection firm enough for intercourse, and dietary data was collected every four years from 1986.
The researchers found that men who consumed foods high in flavonoids - particularly anthocyanins, flavones and flavanones - had a lower risk of erectile dysfunction than men who did not consume such foods.
Anthocyanins are present in blueberries, cherries, strawberries, blackberries, radishes and blackcurrants, while flavones and flavanones are found in citrus fruits.
"The top sources of anthocyanins, flavones and flavanones consumed in the US are strawberries, blueberries, red wine, apples, pears and citrus products," Professor Cassidy noted.
Men with a higher total fruit intake were found to have a 14 per cent reduced risk of erectile dysfunction, compared with men with lower total fruit intake, and men who regularly consumed foods rich in anthocyanins, flavones and flavanones had a 10 per cent reduced risk of erectile dysfunction.
"In terms of quantities, we're talking just a few portions a week," Professor Cassidy added.
Meanwhile, men who combined a flavonoid-rich diet with regular exercise were found to have a 21 per cent reduced risk of erectile dysfunction, compared with men with low flavonoid consumption and low physical activity.
After accounting for potential confounding factors, including physical activity, body weight, caffeine consumption and smoking status, the findings remained.
Overall, the link between a flavonoid-rich diet and reduced risk of erectile dysfunction was stronger for younger men.
The researchers published their findings in The American Journal of Clinical Nutrition.