Honolulu: Research carried out by the Cancer Center of Hawaii has found that just two daily servings of soy reduced levels of the prostate cancer marker PSA in men by 14 percent.

Doctors test PSA (prostate-specific antigen) levels in men to screen for prostate cancer. The Hawaii indings support previous studies which suggest that soy may reduce the risk of prostate cancer development and progression.They also show that levels of the male hormone testosterone were unaffected. The results of the new randomized, crossover clinical trial, are published on-line in the European Journal of Clinical Nutrition

The isoflavones of soy are phytoestrogens and exert mild estrogen-like action.

The researchers at the Cancer Research Center of Hawaii, recruited 23 men with an average age of 58.7 and randomized them to receive either a high soy diet of two servings of soy per day or a low soy diet normal diet for three months. The the first test period, was followed by a one-month break and then the men crossed over to eat the other diet for a further three months.

The research adds to a growing number of studies linking soy-containing diets to lower incidences of prostate cancer. But longer and larger trials are needed to confirm or challenge these findings.

There are over half a million news cases of prostate cancer that are diagnosed every year world wide, and the cancer is the direct cause of over 200,000 deaths. The incidence of the disease is also increasing with a rise of 1.7 per cent over 15 years.

The lowest incidences of the cancer are found in China, Japan and India, with experts linking this to a high dietary intake of soy products. A recent meta-analysis from the International Journal of Cancer reported that men who regularly consumed soy-containing products had a 30 per cent lower risk of the cancer.