Research suggests that women with vitamin D deficiency may have a higher risk of developing breast cancer. Vitamin D may also play a role in controlling normal breast cell growth and may be able to stop breast cancer cells from growing.
You likely already know that vitamin D helps the body absorb calcium, which is essential for good bone health. Vitamin D also helps the immune, muscle, and nervous systems function properly. Most vitamin D is made when an inactive form of the nutrient is activated in your skin as it’s exposed to sunlight.
Smaller amounts of vitamin D are found in fortified milk, breads, and cereals, and in fatty fish and eggs. As more and more people spend most of their time out of direct sunlight or wearing sunscreen when they are in the sun, vitamin D production from sun exposure becomes limited. This is especially true during the darker fall and winter months. Therefore, many people opt for a high-quality vitamin D supplement.
Vitamin D may help reduce breast cancer by:
- Controlling how quickly breast cells multiply.
- Improving cell cohesiveness with other cells so they don’t grow out of control.
- Inducing abnormal cells to go into a programmed death.
- Reducing inflammation.
Before you adjust your vitamin D intake, it’s important to know your vitamin D serum level. This is done with a simple blood test that your doctor can order for you during your routine physical. Vitamin D researchers recommend a serum level of 40-60 ng/ml (nanograms/milliliter).
Also be sure to talk with your doctor about your serum levels and which supplements would be best for you. If your level is low, once you’ve been taking a supplement to get back into the normal range, have your vitamin D level checked again in a few months and adjust your supplement dose accordingly. Taking too much vitamin D can occasionally cause too much calcium in your blood. When choosing a vitamin D supplement, most experts recommend taking the D3 form of the vitamin.