NEW YORK (Reuters Health) - Men may be able to halve their risk of aggressive prostate cancer by adding large amounts of broccoli and cauliflower to their menu. However, the overall risk of prostate cancer was not changed.
In a study of nearly 30,000 men, Dr. Richard B. Hayes of the National Cancer Institute in Bethesda, Maryland and colleagues found that men who ate more than a serving of either vegetable each week had roughly half the risk of developing advanced-stage prostate cancer — that had spread beyond the prostate gland — compared with their peers who ate these vegetables less than once a month.
A number of studies have linked high fruit and vegetable diets with lower prostate cancer risk, but these results have been mixed. Few investigators have looked at advanced disease, Hayes and his team note in the Journal of the National Cancer Institute. Hayes and his colleagues looked at 29,361 men who were being followed as part of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial.
During more than 4 years of follow-up, 1,338 of the men developed prostate cancer. While there was no overall link between fruit and vegetable intake and prostate cancer risk, men who ate the most veggies had a 49-percent lower risk of being diagnosed with prostate cancer that had advanced to stage III or IV (on a scale of I to IV), the researchers found.
Most of the effect appeared to be due to cruciferous vegetables, which include Brussels sprouts, cabbage, broccoli and cauliflower; larger amounts of any vegetables in this family cut risk by 40 percent.
Broccoli and cauliflower appeared to have the biggest impact. Men who ate broccoli more than once a week had a 45 percent lower risk of advanced prostate cancer than those who ate the vegetable less than once a month, while eating cauliflower this often cut risk by 52 percent.
There was also a tendency toward reduced risk of aggressive disease among men who ate raw or cooked spinach at least twice weekly, compared to those who ate the vegetable less than once a month.
Cruciferous vegetables are rich in glucosinolates, note Hayes and his team, which can produce other chemicals with anti-carcinogenic effects. The vegetables also are powerful antioxidants.
If it is ultimately found that these vegetables directly lower the risk of aggressive prostate cancer, “a possible means to reduce the burden of this disease may be primary prevention through increased consumption of broccoli, cauliflower, and possibly spinach,” they conclude.
SOURCE: Journal of the National Cancer Institute, August 1, 2007.