High daily intake may lower cancer risk, aid weight loss

By Karen Collins

Jan. 10 — Calcium is probably best known for its role in keeping bones strong, but research now points to two other possible health benefits: weight control and lower risk of some cancers. If further study supports these links, it could create even greater concern that only one-third of Americans meet their calcium needs. A REPORT in the Journal of the American College of Nutrition discussed several studies in which people who consumed less calcium tended to be more overweight and have greater midlife weight gain. Each daily intake of 300 milligrams of calcium (about eight ounces of milk) was associated with about six pounds lower weight in adults. Yet people trying to lose weight may give up milk because they think it’s too fattening. It may be that, rather than low calcium causing overweight, perhaps being overweight leads to low calcium.

INCREASED WEIGHT LOSS

At least two studies have reported that weight-reduction diets with more dairy products and higher calcium produced greater weight loss.

A two-year Purdue University study found that, calorie consumption being equal, people consuming 1,000 mg of calcium — the adult recommendation — lost more weight and fat than those consuming only 600 mg, the average for women. Calcium, however, was not a magic fat-burner. The effect was seen only at calorie intake below the group average. Those who consumed more calories than they burned still stored the excess as fat, regardless of calcium intake. Research from the University of Tennessee, published in the Journal of the American College of Nutrition and elsewhere, suggests that greater dietary calcium makes cells less likely to store fat and more likely to burn fat when calorie intake is reduced. In a complex chain of events, too little calcium in the diet brings cell changes that lead to decreased fat-burning and increased fat storage.



LOWER RISK OF CANCER

Some studies suggest that getting enough calcium might also lower the risk of cancer. The strongest evidence links colon cancer with calcium. In two large

studies reported in the Journal of the National Cancer Institute, people with higher calcium consumption developed 35 percent fewer cases of a certain type of colon cancer than people with low-calcium diets. In a study in the journal Nutrition and Cancer, increased calcium consumption caused the cells that line the colon, in the area where cancer often begins, to change into lower-risk cell types. In the Nurses’ Health Study, calcium in the diet did not affect the risk of breast cancer in women after menopause, but pre-menopausal women with higher calcium consumption developed about 30 percent less breast cancer than those who consumed very little. Another study suggests that calcium may offer some protection against ovarian cancer. Much more research is needed, however, to confirm these links.

Adding confusion, some studies link higher calcium consumption with greater risk of prostate cancer. Not all studies show such a link, however, and some cases of greater risk with increased dairy products may be related to an overall increase in food and calories.

With calcium, is it a case of the more, the better? No. In studies of cancer risk, calcium was protective at levels of 700 to 900 mg a day. Studies of weight control found benefits from 1,000 to 1,500 mg daily, which is what we get in a balanced diet that includes three servings of dairy products or calcium-fortified foods a day. These studies suggest more potential benefits of meeting the current recommendations of the National Academy of Sciences (1,000 mg for adults through age 50, and 1,200 mg for older adults), but they don’t imply we need to go beyond them.