TORONTO: Two glasses of tomato juice a day strengthens bones and can ward off osteoporosis, say scientists.

The key ingredient is thought to be lycopene, the antioxidant already credited with cutting the risk of prostate cancer in men and protecting against heart disease.

Researchers at the University of Toronto in Canada asked 60 post-menopausal women, aged 50 to 60, to cut out all tomato products from their diet for a month.

This led to a significant increase in blood levels of N-telopeptide, a chemical released into the bloodstream when bone is being broken down.

Then, for four months, the women were given a daily dose of standard tomato juice containing 15mg of lycopene, an enriched version with 35mg of lycopene, lycopene capsules or dummy capsules.

This led to a significant drop in levels of N-telopeptide in women drinking either type of juice or taking the capsules. But there was no benefit in women taking the dummy capsules.

Standard supermarket juice was just as good as the lycopene-enriched one, said researchers.

Two glasses a day of tomato juice containing 15mg of lycopene could be enough to strengthen brittle bones, the journal Osteoporosis International reported.