Node Smith, ND
A recent study revealed that women with higher levels of serum vitamin D have significantly lower breast cancer risk.1
Many people who lack sun exposure on a regular basis may have low levels of the hormone
Vitamin D, actually a hormone synthesized in the skin, has been associated with numerous health outcomes, from lowering cardiovascular risk factors to lower autoimmune disease rates. Since vitamin D is synthesized in the skin from exposure to UVB light, many people who lack sun exposure on a regular basis may have low levels of the hormone. A modern lifestyle that promotes indoor activities much of the time lends itself to low levels of vitamin D on a population scale.
In this specific study, data was combined and analyzed from two randomly controlled trials from Creighton University. More than 5000 women, over the age of 55 were selected, with a broad range of vitamin D levels.
The study saw that women with a level of vitamin D above 60 ng/ml had an 80 percent lower risk for breast cancer than those with a serum level of 20 ng/ml or lower. There was also a dose response relationship of cancer incidence when serum vitamin D levels were between 20 and 60 ng/ml – ie the higher the vitamin D level, the lower the breast cancer risk.
Principal investigator notes similar correlations with all-type cancer risks and vitamin D levels
The principal investigator, Joan M. Lappe, PhD, RN, has also seen similar correlations with all-type cancer risks and vitamin D levels. In a 2007 study, she found that women who took vitamin D and calcium over a four-year period were 60 percent less likely to develop any type of cancer than women taking placebos. In 2017, she found that vitamin D levels of 55 ng/ml had a 35 percent lower risk of all-type cancer than women with levels of 30 ng/ml.
Recommendations for vitamin D levels still not influenced by this data
The recommendations for vitamin D levels are still not being influenced by data such as this. The National Academy of Science still recommends a vitamin D level at or above 20 ng/ml as adequate for bone health. This may be adequate for bone health specifically, though other disease factors show associations with pathology at these low levels, and it is possible that these recommendations need to be changed.
- McDonnell SL, Baggerly CA, French CB, et al. Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥60 vs <20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort. Plos One, June 15, 2018. https://doi.org/10.1371/journal.pone.0199265
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Node Smith, ND, is a naturopathic physician in Portland, OR and associate editor for NDNR. He has been instrumental in maintaining a firm connection to the philosophy and heritage of naturopathic medicine among the next generation of docs. He helped found the first multi-generational experiential retreat, which brings elders, alumni, and students together for a weekend camp-out where naturopathic medicine and medical philosophy are experienced in nature. Four years ago he helped found the non-profit, Association for Naturopathic ReVitalization (ANR), for which he serves as the board chairman. ANR has a mission to inspire health practitioners to embody the naturopathic principles through experiential education. Node also has a firm belief that the next era of naturopathic medicine will see a resurgence of in-patient facilities which use fasting, earthing, hydrotherapy and homeopathy to bring people back from chronic diseases of modern living; he is involved in numerous conversations and projects to bring about this vision.
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