What is vitamin D? Vitamin D is a hormone precursor that has a primary function of promoting healthy bone formation by regulating calcium absorption in the gut and maintaining adequate calcium and phosphorus levels in the bloodstream. Vitamin D also plays a number of other critical roles in the body, including modulation of the immune system, cell growth, the inflammatory response, and neuromuscular function. It has been associated with health benefits in the prevention and treatment of many different diseases, including autoimmune disease.
Is it necessary to supplement with vitamin D if you have autoimmune disease?
While it has become increasingly common for conventional and functional medicine practitioners alike to recommend vitamin D supplementation, there is still quite a bit that modern science does not fully understand about vitamin D, including what constitutes an adequate vitamin D level and if it is necessary for everyone to supplement with it. It is certainly clear that vitamin D plays a vital role in health, but the evidence is building to suggest that low vitamin D levels are a consequence or a biomarker of poor health, and not necessarily the root cause of disease. This is an important distinction to make when determining what constitutes an optimal vitamin D level and when it is necessary to begin supplementation. Supplementing with mega doses of vitamin D may not provide a high level of protection against the development or progression of autoimmune disease, and in some cases, it may be harmful. Because of the correlation between low vitamin D levels and autoimmune disease, a simple blood test for 25-hydroxyvitamin D3 is a good place to begin if you are considering vitamin D supplementation.
There is no consensus on the optimal blood levels of vitamin D within the functional medicine community. However, there are several recent studies that suggest the optimal range of vitamin D is likely lower than once was embraced by integrative health practitioners and higher ranges are not necessarily more desirable. In general, a range of 25 – 50 ng/mL may be optimal for most people. There isn't sufficient evidence that levels above 50ng/mL are beneficial, and in fact, they may increase the risk of decreased bone mineral density, kidney stones, and cardiovascular disease. For people with autoimmune disease that have symptoms under control and their vitamin D level falls within 25 - 50 ng/mL, supplementation is likely not necessary, especially if they are taking other measures to ensure adequate vitamin D. However, if an individual is struggling with autoimmune symptoms and their vitamin D level falls within the lower end of the range, it may be beneficial to begin supplementation.
Besides supplementation, what are ways to ensure an optimal vitamin D level?
The most efficient way to ensure optimal vitamin D levels is through sunlight exposure in which UVB radiation converts cutaneous 7-dehydrocholesterol (a form of cholesterol) to vitamin D3, which is eventually processed to become the biologically active form of 1,25-dihydroxyvitamin D3. There are several factors that impact the production of vitamin D from sun exposure, including skin color, weather conditions, latitude and longitude, time spent in the sun, season, time of day, and the use of sunscreen and clothing. This calculator created by the Norwegian Institute for Air Research can be used as a general guideline for estimating the amount of sun exposure you need in order to produce an optimal level of vitamin D depending on these factors.
During winter in many northern climates, it may be challenging to obtain enough sunlight to produce adequate levels of vitamin D, especially if you are struggling with health concerns and you are not within an optimal range of vitamin D levels. An alternative to natural sunlight exposure is a sunlamp that emits enough UVB radiation to allow the production of vitamin D, while minimizing UVA exposure. In the United States, the Sperti Vitamin D Lamp is the only sunlamp approved by the FDA for the purposes of increasing vitamin D levels. A clinical trial found that this sunlamp was effective in raising serum 25-hydroxyvitamin D3 levels.
Adequate levels can also be ensured by consuming foods that are rich in vitamin D, including organ meats, fatty fish, pastured lard, grass-fed butter, and pastured eggs. During the winter months in which sunlight exposure is limited, you should increase your consumption of these foods and consider taking a high quality extra virgin cod liver oil (EVCLO) (such as this product by Rosita Real Foods) and butter oil (such as this product by Corganic). A critical factor to consider in vitamin D supplementation is that vitamin D requires adequate levels of the fat-soluble vitamins A and K2 and several minerals, such as magnesium, zinc, and boron, in order to perform its role in the body. Real food sources of vitamin D usually contain vitamin A present in the correct amounts needed to balance vitamin D. Vitamin K2 can be found in natto, egg yolks, grassfed butter, pastured chicken, and grass-fed beef. Unlike a vitamin D supplement, EVCLO and butter oil will include sources of vitamin D, A, and K2 that are bioavailable and more easily absorbed. Although many people that are dairy intolerant can safely consume butter oil because the milk proteins are removed, it is not advised to take this real food supplement if you are on the elimination phase of the Paleo Autoimmune Protocol.
What else should you know about Vitamin D supplementation?
Consuming a nutrient-dense real food diet that contains the minerals that are co-factors of vitamin D is also a key component to ensuring adequate vitamin D levels. In particular, magnesium plays several critical roles in the production and metabolism of vitamin D. A magnesium deficiency can often be an overlooked cause of low vitamin D levels. Foods rich in magnesium include dark, leafy greens, fish, avocado, bananas, dark chocolate, nuts, and seeds. Because of the importance of magnesium to adequate vitamin D levels, it is wise to supplement with magnesium if your vitamin D levels are low.
If you do determine that it is necessary to supplement with vitamin D, be cautious because not all vitamin D supplements are created equal. It’s important to chose a supplement with cholecalciferol (vitamin D3) versus ergocalciferol (vitamin D2). Although you won’t find any dietary supplement that includes all of the vitamin D co-factors, there are professional line supplements that pair vitamins D3 and K2 and that would be the better option. Keep in mind that it is possible to reach toxicity with vitamin D. While supplementing, you should continue to monitor your vitamin D blood levels and eat a nutrient-dense diet that is rich in the vitamins and minerals that work synergistically with vitamin D.