After spending the past five days in a beach chair in San Juan I figured the importance of optimal vitamin D intake, aka the sunshine vitamin, would be the perfect thing to blog about.
Most everyone knows that vitamin D plays a key role in bone health, but did you know that vitamin D deficiencies have also been present in many chronic and life threatening conditions? A research team at the University of Kentucky just recently found that rats fed vitamin D deficient diets showed significant decreases in learning and memory (5) and in 2009 the Dermato-Endocrinology Journal published an article stating that optimal levels of vitamin D could reduce the rates of cancer by 35%, type 2 diabetes by 33%, and all cause mortality by 7% (¹)(²). Vitamin D deficiencies have also been associated with depression, heart disease, fibromyalgia, immune system imbalances and autoimmune disorders (³).
Vitamin D regulates over 150 genes within our bodies and plays key roles in calcium absorption and blocking the parathyroid hormone, a hormone that makes bones brittle and thin. Once vitamin D is ingested or absorbed in our bodies it is converted by the liver and kidneys into the only active form, vitamin D3. From there vitamin D goes on to interact with the receptors on nearly every tissue type in our body; regulating genes, cell growth and development, immune system function and metabolic controls (³). Isn’t science fun?
But I’m taking the recommended daily amount of 600 IUs (~30 ng/ml) of vitamin D, so I should be good right? Wrong, over 40% of Americans are considered to be vitamin D deficient. Even though the RDA for vitamin D was updated in 2010, it does not take into account a person’s unique make up of genetics, dietary intakes, sunlight exposure, metabolism etc. Studies have shown that increasing intakes of vitamin D, even up to 4,000 IUs daily, is an acceptable and safe amount, showing no adverse effects on healthy individuals. In fact, summer sunlight exposure in some areas can generate between 10,000-20,000 IUs of vitamin D per hour and fatty fish consumption has been shown to produce up to 10,000 IUs of vitamin D per day (4).
The amount needed to achieve optimal blood levels of 45-60 ng/ml varies depending on individualistic factors like age, where you live, how much time you spend outdoors and the time of year. Your doctor can perform a simple 25-hydroxyvitamin D blood test to measure how much vitamin D is present in your body. If your levels are less than optimal talk with your doctor about upping intake (multiple sources indicate 2,000 IUs daily), eating vitamin D rich foods and spending about 15 minutes a day in the sun, weather permitting; all of these factors can help reduce the physical and economic burdens of vitamin D deficiency.