Low levels of vitamin D may raise breast cancer risk

  • Food sources of vitamin D are limited primarily to some fish species and fish oils, but they are unlikely to give you all the vitamin D you need.

    Food sources of vitamin D are limited primarily to some fish species and fish oils, but they are unlikely to give you all the vitamin D you need. Stock photo

 
By Patrick Massey, M.D.
Posted11/23/2019 6:00 AM

One recent medical discovery is that low vitamin D levels are a risk factor for breast cancer. Earlier research on vitamin D and breast cancer was mixed. Some studies suggested a benefit while others showed no benefit.

One of the problems with these early studies was that measuring the blood levels of vitamin D were rarely done. Vitamin D levels were postulated based on diet, supplementation and even sun exposure. Recent medical research has focused on measuring blood levels of vitamin D and relating these blood levels to the effect of vitamin D on the risk and progression of breast cancer. This is encouraging.

                                                                                                                                                                                                                       
 

Vitamin D represents a group of fat soluble vitamins. Most commonly it is thought to regulate intestinal absorption of calcium, magnesium and phosphate. All cells in the body have receptors for vitamin D -- with the breast, skin, gonads, heart, prostate, white blood cells and brain having the most receptors. This indicates that the role of this vitamin in human metabolism is more complex. It is well known that vitamin D comes from the interaction of sunlight and certain cells in the skin. It is also modified in other tissues to the most active form, vitamin D3. However, the farther north, the less intense the sunlight. In northern Illinois, it is impossible to get all the vitamin D from sun exposure alone.

One recent medical study (2017) published in Environmental Health Perspectives evaluated data from the Sister Study. Between 2003-2009, 50,884 U.S. women (35 to 74 years of age) who had a sister with breast cancer but had never had breast cancer themselves were enrolled. What was discovered was that blood levels of vitamin D greater than 38 ng/ml significantly reduced the risk of breast cancer, especially in postmenopausal women. A blood level of 38 is not overly robust, so the benefit of even a modest amount of vitamin D seems to be important.

Breast cancer cells also have vitamin D receptors but they are fewer in number and do not bind vitamin D as strongly as normal cells. A 2019 study in the International Journal of Vitamin and Nutrition Research demonstrated the fewer the vitamin D receptors on the breast cancer cells, the more aggressive the tumors. This suggests that a consistently higher blood level of vitamin D may be needed for the prevention and treatment of breast cancer. Although often followed in traditional medicine, the National Academy of Medicine daily recommendations for vitamin D are inadequate for breast cancer.

Food sources of vitamin D are limited to primarily some fish species and fish oils. Do not anticipate that you can get substantial amounts of vitamin D from "fortified" foods … you do not. Cooking reduces vitamin D in foods by 40% to 60%. Even multivitamins may not be enough. In my clinical experience, unless you are living close to the equator, vitamin D supplements are the only source of sufficient vitamin D.

• Dr. Patrick Massey is medical director of complementary and alternative medicine at Alexian Brothers Hospital Network, and president of ALT-MED Medical and Physical Therapy, 1544 Nerge Road, Elk Grove Village.

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