Research suggests that women with vitamin D deficiency have a higher risk of developing breast cancer. Vitamin D may play a role in controlling normal breast cell growth and may be able to stop breast cancer cells from growing.
You likely 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 is limited.
A study published recently in the journal, Endocrinology, used mice to explore the relationship between vitamin D and breast cancer. Researchers noted that patients with breast cancer frequently have preexisting vitamin D deficiency when their cancer develops, and the study looked at whether this was coincidental or if low levels of vitamin D contributed to the development of cancer.
The most reliable ways to boost your vitamin D level are to get more direct sunlight exposure, drink fortified milk and take vitamin D supplements.
- Sun Exposure. Even short periods of direct peak sun exposure — 15 minutes 3 times a week, for example — can give you a healthy dose of vitamin D. It’s also impossible to overdose on vitamin D from the sun. While sun exposure offers vitamin D benefits, it does have risks. Sun exposure increases your risk of skin cancer, including melanoma, the most dangerous type.
- Fortified Milk can be a good source of vitamin D. Almost all types of cow’s milk in the U.S. are fortified with vitamin D, but ice cream and cheese are not. In general, an 8-ounce glass of milk contains at least 100 IUs of vitamin D, and a 6-ounce serving of yogurt contains 80 IUs, but the amount can be higher (or lower) depending on how much is added. Some soy and rice milks are fortified with the same amount, but check the label since not all contain vitamin D.
- Supplements are an excellent choice for maintaining healthy levels of vitamin D. But be careful, not all supplements are the same. Look for a minimum of 800 IU per serving as well as one that includes the recommended D-3.
Maintaining adequate vitamin D levels is important to women for both breast cancer prevention and treatment and women should discuss vitamin D with their clinical care team to ensure they are getting the best treatment based on their individual needs.