What do you need to know about Vitamin D?
Vitamin D is a fat soluble vitamin that is necessary for many functions in our bodies. The body makes vitamin D from cholesterol through a process that is triggered by the sun’s ultraviolet B rays. Interesting fact: a study showed that non-Hispanic black subjects require 6 times the amount of UV radiation to product a serum vitamin D concentration similar to that found in non-Hispanic white subjects1. Vitamin D can also be obtained through diet, although most dietary sources of vitamin D do not contain sufficient amounts to satisfy daily requirements. Some of the foods that have high amounts of vitamin D are oily fish such as wild salmon, fortified products, and egg yolks. The daily recommended allowance of vitamin D is 600IU for adults.
Vitamin D is important for calcium balance and optimal skeletal health. One of the major functions of Vitamin D is to help increase the calcium and phosphorus absorption from the small intestine. For proper mineralization of bone both calcium and phosphorus are needed. Another major function of Vitamin D is involvement in the maturation of osteoclasts which play a role in the re absorption of calcium from the bones.
Vitamin D deficiency also is important during pregnancy. Studies show that a maternal vitamin D deficiency at 18 weeks of gestation was associated with multiple problems with the resulting children, including impaired lung development, neurocognitive difficulties, increased risk of eating disorders and lower peak bone mass2. This suggests that vitamin D plays an active role in fetal development particularly with the brain, lungs and bones.
Interestingly enough, one study showed that nearly two-thirds of healthy young adults in Boston were vitamin D insufficient at the end of winter3. It is common for vitamin D levels to be lower in the fall-winter because of the decreased sun exposure and higher at the end of summer. Most commonly there are no symptoms of having a vitamin D deficiency or insufficiency. Some may experience a depressed mood. Your vitamin D levels can be tested through a blood draw and it is recommended to be tested yearly.
vit D So why should you care about your vitamin D levels? Studies show that better IVF outcomes are achieved when a patient has sufficient levels of vitamin D4. Another study showed that supplementation of vitamin D resulted in a 12% reduction in the odds of an acute respiratory infection5. Additionally, low levels of vitamin D have been linked to increased cardiovascular disease6. Another study showed a strong relationship between lower rates of a variety of chronic diseases and a higher level of vitamin D. Finally, low vitamin D is associated with osteoporosis and osteopenia, and an increased risk of hip and non-vertebral fractures. Many studies have suggested a link between low vitamin D levels and an increased risk of cancer7. Another theory is that vitamin D deficiency could also contribute to autoimmune diseases.
So what can we do about your low vitamin D? Depending on your vitamin D levels different recommendations are made. Some need a prescription twice a week or once a week to supplement with until vitamin D levels are normalized then continuing on a maintenance dose. Your clinician can make the best recommendation for you based on your individual situation.
- Clemens TL, Henderson SL, Adams JS, Holick MF . Increased skin pigment reduces the capacity of skin to synthesise vitamin D3. The Lancet. 1982; 319(8263):74-76. sciencedirect.com/science/article/pii/S0140673682902148
- Prue HH, Lucas RM, Walsh JP, et al. Vitamin D in Fetal Development: Findings From a Birth Cohort Study. 2015; 135(1):e167-e173. pediatrics.aappublications.org/content/early/2014/12/09/peds.2014-1860
- Tangpricha V, Pearce EN, Chen TA, Holick MF. Vitamin D Insufficiency among Free-Living Healthy Young Adults. Am J Med. 2002; 112(8):659-662. ncbi.nlm.nih.gov/pmc/articles/PMC3091001
- Paffoni A, Ferrari S, Vigano P, et al. Vitamin D Deficiency and Infertility: Insights From in vitro Fertilization Cycles. The Journal of Clinical Endocrinology and Metabolism. 2014; 99(11): e2372-e2376. academic.oup.com/jcem/article-lookup/doi/10.1210/jc.2014-1802
- Martineau AR, Jolliffe DA, Hooper RL, et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017; 356. bmj.com/content/356/bmj.i6583
- Abuannai M, O’Keefe JH. Vitamin D and cardiovascular health. Primary Care Cardiovasc J. 2011;4:59–62. jcpcarchives.org/full/vitamin-d-and-cardiovascular-health-136.php
- Lappe JM, Travers-Gustafson D, Davies KM, et al. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr. 2007;85:1586–1591. ajcn.nutrition.org/content/85/6/1586.long