Study Finds Possible Link Between Vitamin D Intake and Breast Density

A new study found that higher intake of Vitamin D may be linked with lower breast density, which in turn can reduce the risk of breast cancer or facilitate its detection. The study, which was published in the October issue of Breast Cancer Research, found that among 157 high-risk women, breast density was inversely associated with vitamin D intake.

Study Findings

Lower breast densities reduce risk of breast cancer and make it easier to detect breast cancer via mammography. Breast density is the percentage of total breast area with a mammographically dense appearance, and is an informative marker for breast cancer risk, according to the study.

The American Cancer Society defines high breast tissue density as one of the factors that increases the risk of breast cancer. Breast tissue is primarily composed of the lobes and ducts of the milk glands (ductal tissue) and fat cells. Women with dense or "lumpy" breasts have higher percentages of ductal tissue rather than fatty tissue. This makes it more difficult to see cancerous cells on a mammogram because the ductal tissue and cancerous tissue appear similar in appearance. An annual mammogram and clinical breast exam is still the recommended method to catch early-stage breast cancer, though other technologies are being introduced.

The study, though relatively small in size, is one of the first of its kind to analyze how lifestyle habits such as diet can change breast density and breast cancer. High-risk women were defined in this study as women with a strong family history of breast cancer and/or known hereditary presence of a BRCA-1 or BRCA-2 mutation. Approximately 40 percent of women indicated this breast cancer predisposition gene. The study only examined vitamin D intake via food or supplements, and did not account for how the body naturally produces vitamin D from sunlight.

The study found that women with high levels of vitamin D intake has less breast density. Findings showed that 12.7% (20 women) were classified as entirely fatty, 28.0% (44 women) as having scattered fibroglandular tissue, 34.4% (54 women) as heterogeneously dense, and 24.8% (39 women) as extremely dense. Of these, women in the highest one-third of vitamin D intake were half as likely to have higher breast density as women in the lowest one-third.

Findings Importance

Difficulties in assessing breast density may contribute to the inconsistent results of studies on diet and breast density, according to study authors. This study directly examined how Vitamin D potentially impacts breast density through dietary changes. Overall no other dietary factors were linked with breast density, but the study again indicates that lifestyle changes may help reduce breast cancer risk.

Although the study cannot conclusively state that Vitamin D intake deceases breast cancer risk, the findings do suggest that some dietary modification strategies may be effective in reducing breast density, and hence breast cancer risk, and warrants further study.

Sources:

Breast Cancer Research Journal, Dietary intake and breast density in high-risk women: a cross-sectional study

American Cancer Society, Breast Cancer Facts & Figures 2007-2008