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Losing your Vitamin D, libido, and metabolism? It’s Your Genes!

Check out Dr. Laurie Marti’s latest blog! If you haven’t heard, she’ll be joining our practice every other Wednesday!


Practically everyone knows that vitamin D is important for healthy bones and teeth, but there are so many more functions of this vital nutrient. This includes testosterone

production, metabolism and thyroid function, mental health, normal immune function, cardiovascular disease prevention, and cancer survival. Testing for vitamin D in the

blood is commonly performed, but few people know that genetics play a role in your vitamin D level and function and can be tested. Here in the Puget Sound, where the

sunlight (the main source of vitamin D) is sparse most of the year, it is especially important to know the health benefits of vitamin D, testing for vitamin D, and how to

maintain optimal levels both through good nutrition and dietary supplementation.


Vitamin D has been one of the most studied nutrients in recent years, with the majority of studies demonstrating the benefits of healthy vitamin D levels. Vitamin D is a “steroid”

type of compound, which means it can enter into the nucleus of cell and change its DNA to instruct it to perform various functions, even to kill itself, if it a nonviable or

“cancerous” cell. Vitamin D literally controls hundreds of genes, and adequate amounts in the body are necessary for proper functioning of the hormonal, neurological, immune,

and metabolic systems. Some of the clinically studied benefits include decreased risk of cardiovascular disease/strokes, osteoporosis, diabetes, depression, infertility, dementia,

irritable bowel syndrome, cancers (ovarian, breast, prostate, colon, lymphoma, and lung), and autoimmune conditions.


Vitamin D is produced in human skin during the exposure to Ultraviolet B (UVB) radiation from sunlight. The amount produced is affected by many factors, including

latitude, time of day, season, and skin pigmentation. In 2002, the Journal of Endocrinology reported that at latitudes above 40 (N or S), the skin’s conversion to

vitamin D from sun exposure, does not occur in winter months, and as you get further away from 40 degrees latitude, even summer synthesis is decreased. Vitamin D

supplementation may be necessary all year long for those living in certain areas, like Seattle, which is at 47 degrees N. Living in urban areas can also influence vitamin D

synthesis, as ozone levels are often higher in urban settings. A 2008 study reported findings that urban inhabitants had much lower vitamin D levels than rural inhabitants,

concluding that ozone decreases the ability to photosynthesize vitamin D from the sun.


Besides exposure to sunlight, there are other sources of vitamin D. The most robust sources are the fatty fishes, such as salmon (wild type has almost 4 times the amount of

vitamin D compared to farmed salmon), sardines, tuna, and mackerel. Shiitake mushrooms also contain an impressive amount of vitamin D. For those that do not have

access to eating these rich-sources of vitamin D and/or exposure to regular UVB radiation from the sun, dietary supplementation from a reputable manufacturer is



Consuming excessive amounts of vitamin D, without knowing the body’s level, is not advised. There have been studies that have shown there may be some downsides to

excessive vitamin D levels. One study reported an increase in falls in the elderly with excessive vitamin D levels. Another study, based on the review of the health records of

over 100,000 patients, revealed that a dangerous arrhythmia, atrial fibrillation, was more likely to occur in those with excessive vitamin D levels.


Optimal testing of vitamin D is a two-step process. First, a blood test will check the level of vitamin D3 and D2. Next, a genetic test will assess the ability of cells to recognize and

absorb the vitamin D, since the work of vitamin D is performed inside the cells. Cells have receptors that function like “gates” to allow vitamin D to enter the cell. These

receptors can be dysfunctional in those with specific genetic mutations. These mutations have been associated with higher risks of vitamin D deficiencies, gum disease,

inflammatory bowel disease, diabetes, and breast cancer. Genetic testing assists in formulating the proper supplementation regimen, as higher daily vitamin D dosages may

be necessary, and other specific nutritional supplements can improve the function of the receptor itself. A salivary genetic test is available to identify if you have these Vitamin D

Receptor “VDR” mutations.


Vitamin D is a critical nutrient as it affects so much of the way the human body will perform. For optimal physical and mental performance, it is advised to test the vitamin D

blood levels and the genetic VDR mutations. Make an appointment with Eastside Primary Care and Wellness to assess these and obtain advice on appropriate nutritional



Laurie A. Marti, MD