Garlic lovers got some good news in a recent study from China, which suggests that a daily serving from the allium group of vegetables - garlic, scallions, onions, leeks, and chives - may help protect against the development of prostate cancer. The findings are reported in a recent issue of the Journal of the National Cancer Institute.

Study assessed effect of foods

Researchers from the National Cancer Institute in the US and the Shanghai Cancer Institute recruited 238 men with prostate cancer and 471 healthy men (who served as the control, or comparison group). All of them completed a questionnaire that recorded their intake of allium vegetables over the previous 5 years.

The researchers found substantially less risk of prostate cancer among the men who ate more than 10 grams of these vegetables a day, when compared with those who ate less than 2.2 grams/day. (To get an idea of how much this is, 3½ cloves of garlic weigh about 10 grams.) Of these vegetables, garlic and scallions appeared to have the most protective effect.

What makes these foods so healthy?

Consumers who follow nutrition and health news probably already know about the disease-fighting potential of allium vegetables - especially garlic. These vegetables are prime sources of flavonoids and sulfur-containing compounds - both have been shown in laboratory studies to reduce tumor growth.

Scientists are not yet sure how these substances help keep cells healthy - they may inhibit the cell division and proliferation that triggers cancer, and they may help to keep the cells' DNA in good repair. There is also some research that suggests that an ingredient in garlic may help modulate the effect of hormones on prostate cells - a step that could inhibit the development of prostate cancer.

Advice to consumers

The connection between diet and the development of prostate cancer remains unclear. Scientists suspect that a diet high in fat - especially saturated fat from animal products - may increase the risk, while a vegetable-rich diet may moderate that risk. And, with studies such as this one, they are gaining a better understanding of the possible benefits of a group of vegetables used in relatively large amounts in Chinese cuisine, but commonly used in Western cuisine as a flavoring rather than as a major component of a dish.

Note, though, that the participants who ate the most garlic and onions and Chinese chives also ate the most cruciferous, green leafy, and dark orange vegetables. They also tended to eat more isoflavone-rich foods like tofu and soy milk. All of these foods likely contributed to the lower cancer risk observed in this study.

This underscores the point that no one food - or group of vegetables - is likely to possess an overriding effect on cancer risk. The American Cancer Society estimates that about one-third of cancer cases could be prevented if consumers followed some basic eating and exercise advice:

• eat at least 5 servings a day of fruits and vegetables
• choose whole grain foods over refined grains
• limit the intake of red meat, especially processed meats and high-fat cuts
• maintain a healthy weight
• exercise for at least 30 minutes on most days of the week

Check the American Cancer Society website (the first link below) for more information on what men can do to reduce their risk of developing prostate cancer.