Vitamin D: Can it Decrease Your Risk of Breast Cancer?

Some exciting news!  A new study has found an association between higher levels of Vitamin D and lower rates of breast cancer. (1).  This is good news for both women, who have been diagnosed with breast cancer and those who want to prevent it.

Breast cancer is the most common non-skin cancer in women with more than 252,000 new cases/year in the United States.  Early detection and improved treatments have reduced mortality rates but there has not been any reduction in the incidence of breast cancer in the past 20 years.  Finding primary preventative strategies, such as using supplements, could reduce the incidence.  This is exactly what scientists at the University of California, San Diego in collaboration with other universities have found.  In this study, researchers noted that women with the highest Vitamin D levels, greater than or equal to 60 ng/ml, had an 80% lower risk of breast cancer compared to women with concentrations less than 20 ng/ml. 

What is Vitamin D?

Vitamin D, also known as the sunshine vitamin, is not only a fat-soluble vitamin but also a hormone.  Vitamin D helps our bodies absorb calcium, which is essential for good bone health and promotes the immune, muscle and nervous systems to function at their optimal levels. Most vitamin D is made when an inactivated form of the nutrient is activated in your skin when exposed to sunlight. Smaller amounts of Vitamin D can be found in fortified milk, fatty fish and eggs.


Why do we need supplements? Don’t we get enough from the sun?

As we age, our skin does not absorb as much Vitamin D from the sun as when we were younger. In addition, we have been cautioned by our dermatologists regarding the harmful effect of ultraviolet radiation on skin cancer risk. Thus, many of us are applying more sunscreen to prevent skin cancer which also decreases the amount of Vitamin D that our bodies can absorb.

Some studies recommend short periods of sun exposure —15 minutes 3-4 times a week for example,— to provide the recommended daily amount of Vitamin D. Yet, even in sunny areas, Vitamin D levels can be low and supplementation may be needed to achieve the optimal level.

Amount recommended for Cancer prevention: How much should we take?

Before you adjust your Vitamin D intake, it is important to have your Vitamin D level checked. This can be done with a simple blood test for 25-hydroxyvitamin D that can be ordered by your primary care provider. Some Vitamin D researchers recommend a serum level of between 40-60 ng/ml (nanograms/milliliter) while others may shoot for a level of 70-80 ng/ml.  To achieve these levels, the recommended daily amount of 400-800 IU/day may not be sufficient.

How does Vitamin D help with the reduction of breast cancer risk?

According to Cedric Garland, Ph.D, one of the authors of this new study, from the Department of Family and Preventive Medicine at the University of California, San Diego, believes there may be various ways that biologically active form of Vitamin D, 1,25(OH)2 D3, decreases the risk of developing breast cancer. These include activating immune cells, suppressing inflammation and protecting cells from DNA damage as well as other cancer-preventing pathways.

For women with a history of breast cancer, higher Vitamin D levels have been associated with lower risk of recurrence.  Dr. Garland states that “Vitamin D makes cell stick together, particularly breast epithelial cells”. This occurs through production of a certain molecule called E-cadherin. Dr. Garland continues that “ if Vitamin D level gets low, the cells of the breast epithelium don’t adhere to each other, and when a cell is not tightly adhered to its neighbors, its stem cell undergoes mitosis”. Mitosis is cell division. The cells that reproduce the fastest then can produce a cancerous clone of rapidly dividing cells. These cells can ultimately penetrate the cell membrane, leading to leakage into the lymphatics (also known as metastases). When Vitamin D levels are high, the cells stick together and decrease the risk of cell division thus reducing the risk of metastases.

What should you do?

Ask your health care provider to check your Vitamin D level (25-OH Vitamin D) as well as your calcium level (2). If you are deficient in Vitamin D, supplementation might be recommended if your calcium level is normal. If your calcium level is not normal, then other testing should be done to evaluate the Vitamin D deficiency.

There are many ways to increase your Vitamin D levels ranging from sub-lingual drops (1,000 – 5,000 IU) to high dose capsules (50, 000 IU).   Please consult with your health care provider before starting any supplementation as too high levels of Vitamin D can be harmful to your body.

In health and happiness!




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