Women who consume more calcium, whether by supplements or through dairy foods, appear to have a lower risk of all kinds of cancer, new research finds.

What's more, both men and women with high calcium intakes have lower risks of colorectal cancer and other cancers of the digestive system, says the Archives of Internal Medicine study.

The study was a huge one, involving data from 293,907 men and 198,903 women who participated in the National Institutes of Health-AARP Diet and Health Study.

The study participants took a food questionnaire when they enrolled in 1995 and 1996, and reported how much and how often they consumed dairy and a wide variety of other foods. They also recorded which vitamins and supplements they took each day. They were then tracked to see how many of them developed cancer by 2003.

They found that calcium intakes seemed to have no effect on whether men developed cancer. But in women, the risk of developing any kind of cancer dropped in those who took up to 1,300 milligrams per day. After that limit, they noticed no further risk reduction.

When it came to cancers of the digestive system, for both men and women, the more dairy food and calcium the participants consumed, the less likely they were to develop cancer.

The one-fifth of men who consumed the most calcium through food and supplements (about 1,530 milligrams per day) had a 16 per cent lower risk of these types of cancer than the one-fifth who consumed the least (526 milligrams per day).

For women, those in the top fifth of calcium consumption (1,881 milligrams per day) had a 23 per cent lower risk than those in the bottom fifth (494 milligrams per day).

The decreased risk was particularly pronounced for colorectal cancer.

"In conclusion, our findings suggest that calcium intake consistent with current recommendations is associated with a lower risk of total cancer in women and cancers of the digestive system, especially colorectal cancer, in both men and women," the authors write.

Health Canada recommends that individuals over the age of 50 get 1,000 to 1,500 mg of calcium each day, mostly because of its known role in bone health. A glass of milk for example has about 300 mg of calcium.

Previous research has found that calcium seems to reduce abnormal growth among cells in the gastrointestinal tract and breast. In addition, it binds to bile and fatty acids, potentially reducing damage to the mucous membrane in the large intestine.

Dairy food, which is relatively high in potentially anti-carcinogenic nutrients such as vitamin D and conjugated linoleic acid, is thought to protect against the development of colorectal and breast cancer, the authors write.