Low Vitamin D & Breast Cancer

According to the American Cancer Society, approximately 1 in 8 women will develop breast cancer in their lifetime. While there is no surefire way to prevent breast cancer altogether, there are very specific risk factors for breast cancer, including older age, age of first pregnancy, early onset of menstruation, late menopause, use of estrogen and progestin menopausal hormones, and alcohol consumption. While many of these risk factors are not easily modifiable, research indicates that vitamin D may play an important role in breast cancer prevention.

About Vitamin D

Vitamin D is a fat-soluble vitamin that is most commonly associated with bone health, because it facilitates calcium absorption and regulates calcium levels in the blood. According to the Linus Pauling Institute at Oregon State University, vitamin D may play a role in the prevention of a number of other conditions, including cancer, cardiovascular disease, multiple sclerosis and rheumatoid arthritis.

Research

A 2006 article from the "American Journal of Public Health," by Garland and colleagues, sheds light on the state of the research on vitamin D and breast cancer prevention. The authors note that of the 13 studies they reviewed regarding the link between breast cancer and vitamin D, nine of the studies showed that higher vitamin D intake or higher blood levels of vitamin D or sunlight exposure were associated with decreased risk for breast cancer. The authors also note that one particular study showed that women with the highest vitamin D intake had one-fifth the risk for breast cancer compared to women with the lowest vitamin D intake. Furthermore, breast cancer death rates tend to be higher in places with minimal sunlight in the winter when compared to sunnier areas, suggesting a role for vitamin D, as it can be manufactured in the skin in response to sun exposure.

Mode of Action of Vitamin D

According to Garland and colleagues, vitamin D may reduce breast cancer incidence by inhibiting breast cell reproduction. This makes sense, as one hallmark of cancer cells is unchecked cell division.

Sources of Vitamin D

Vitamin D comes from two main sources -- manufacture by the skin in response to sunlight or via ingestion of food or supplements. Vitamin D occurs naturally in a limited variety of foods such as fish, liver and egg yolk. Vitamin D is also found in fortified foods such as breakfast cereals, orange juice and soy milk. Alternatively, Vitamin D can be obtained from a multivitamin supplement or as a solo vitamin D supplement.

Daily Requirement for Vitamin D

The current adequate intake for vitamin D is 200 international units per day for adults up to 50 years old, 400 IU for adults 51 to 70 years old and 600 IU for adults over 70. Some experts, including Garland and colleagues, recommend higher levels for cancer prevention. The authors suggest a 1,000 IU daily vitamin D supplement to help prevent cancers, including breast cancer.