A new Canadian study has suggested that giving vitamin D supplements to men with rising rates of prostate tumour markers (PSA) seems to slow down the rate of tumour growth, Xinhua reports.

It was a small study and this is very preliminary evidence, but doctors do see a connection between vitamin D levels and PSA levels, Canadian Television quoted the study as saying.

"The PSA levels seemed to reflect a seasonal variation in vitamin D levels," said Lawrence Klotz, a urologist at Sunnybrook and Women's College Health Sciences Centre.

Researchers followed 190 men for the study. They found that, overall, their PSA levels were flat during the summer but rose during autumn and winter at the rate of about one percent each month.

The doctors then gave the men 2,000 international units of vitamin D during those months.

The vitamin seemed to cut the rise in PSA rates by more than half. Without vitamin D, PSA rates rose by about five percent. With vitamin D, PSA rates only rose by two percent.

"As far as I know, there is no other nutrient studied that has shown a slowdown in the rate of rise of a PSA," said Reinhold Veith, a professor at the University of Toronto and a leading researcher in vitamin D research.