Q: Should people give up dairy and use just soy or is a combination of both a better choice?
– Amy in Massachusetts

A: The choice depends on your food preferences and health risks. Milk is the best natural source of the most absorbable calcium in the diet, a mineral most Americans don’t get enough of, placing them at risk for osteoporosis, colon cancer, and possibly hypertension. Milk sugar – lactose – aids in calcium absorption, as does the vitamin D in milk. Of course, if you are lactose intolerant, you’ll need to drink lactose-treated milk or drink milk in small amounts with food. The only other problem with milk is the fat, so if osteoporosis is your concern and you love milk, then choose nonfat milk and milk products and drink at least three glasses a day. Soy is a poor source of these nutrients, unless the product has been fortified. On the other hand, fortified soy milk is an excellent source of calcium and vitamin D, and contains phytoestrogens, which also aid in bone maintenance as well as the prevention of heart disease and possibly breast and prostate cancer. If you love soymilk, then include 1 to 3 glasses a day. There is some suspicion that excessive intake of soy could increase cancer risk in people with a history of breast cancer. Although not yet substantiated, if this pertains to you, your best bet is to limit fortified soymilk to 1 serving a day and fill in the gap with nonfat milk. -Elizabeth Somer

Q: Is soy safe for women who have had estrogen-related tumors?
– Katie from Wisconsin

A: No one knows for sure. Soy contains estrogen-like compounds called phytoestrogens that have a weak estrogen activity. These phytoestrogens bind to estrogen receptor sites and block a woman’s natural estrogen from entering. Researchers suspect that this is one reason why adding soy to women’s diets lowers their risk for breast cancer. On the other hand, some researchers speculate that adding more estrogen to the body, even if it’s a mild form, could escalate cancer risk in women with a history of breast cancer. There are no definitive studies to prove this. On the contrary, cultures where women regularly consume soy, such as Japan, breast cancer rates are very low. In addition, soy-based infant formulas have been used in the United States for more than 30 years with no indication of long-term problems. The bottom line: I recommend that women with no history of breast cancer include several servings of soy in their weekly diets, and that women with a history of breast cancer consume whole soy foods (tofu and soy milk) in moderate amounts, say two or three servings a week. -Elizabeth Somer