Calcium can accumulate in our bodies where it doesn't belong. Is too much calcium intake to blame?

Calcium is the most plentiful mineral in the human body. Almost all of it — 99% — is stored in the skeleton, where it serves to maintain healthy bones and teeth. But that's not all it does. Calcium is also essential for the normal functioning of muscles, blood vessels, and nerves. Tiny amounts are dissolved in the fluid inside and outside every cell in the body. Too much or too little calcium can be deadly to those cells, so the body carefully controls ...

Vaginal dryness is one of the most irritating symptoms of menopause. Here are some ways to relieve it.

Within a few years of menopause, roughly 50% of women develop symptoms related to vaginal atrophy, also called atrophic vaginitis — the deterioration of vaginal tissues due to loss of estrogen. The most common symptoms are dryness, irritation, and pain during intercourse. Although menopause is the most common cause, vaginal atrophy can result from anything that lowers estrogen production. That includes chemotherapy, radiation, removal of the ovaries during hysterectomy, and use of anti-estrogenic therapies such as aromatase inhibitors, tamoxifen (Nolvadex), and ...

Tamoxifen (Nolvadex) is a selective estrogen receptor modulator, or SERM. It's commonly prescribed after surgery for early-stage estrogen receptor–positive breast cancer — that is, breast cancer that's fueled by estrogen. By blocking estrogen's activity in breast cells, tamoxifen reduces the risk of recurrence as much as 50%. For women at high risk, it reduces the likelihood of developing a first breast cancer by the same amount.

Unfortunately, not all women taking tamoxifen get its full benefit. Tamoxifen is converted in the body to its active form, endoxifen, by a member of the P450 family of enzymes called CYP2D6. Some women ...

Bisphosphonates are the class of drugs most frequently prescribed for strengthening bone and reducing fractures; they are FDA-approved for the prevention and treatment of osteoporosis. In November 2008, we first addressed the issue of atypical fractures linked to bisphosphonate use, after the publication of a number of case reports describing low-energy fractures across the femur (thighbone) in postmenopausal women taking alendronate (Fosamax, generic) for five or more years. (Low-energy fractures are caused by falls from no more than standing height.)

Since then, more case reports have appeared, including several involving long-term alendronate takers who developed low-energy fractures in both femurs. ...

Q. I'm 79 years old and have been taking 3,000 mg of vitamin C a day for years. I'm now uneasy about taking this amount and plan to cut back to 1,000 mg daily. Is this the right dose? Will my body be startled by the abrupt change?

A. Cutting back is a wise decision. You've been taking much more vitamin C than you need.

Vitamin C, or ascorbic acid, plays a role in many vital functions, including metabolism and immunity. We can't make it in the body, so we need to get it from dietary sources. It's found in ...