Vitamin D supplementation has huge beneficial health effects. First, lets discuss the physiology of Vitamin D and the effects of deficiency.
The process starts with ingestion of Vitamin D2 (ergocalciferol) from plant sterols or yeast or with Vitamin D3 (cholecalciferol) obtained from oily fish.. UVB irradiation of skin 7-dehydrocholesterol can also produce vitamin D. These vitamin D precursors go to the liver where they are converted to 25-hydroxyvitamin D (which is what your doctor tests for to see if you are deficient in vitamin D!). 25-hydroxyvitamin D is transferred to the kidney where it is converted to the most active form, 1,25 dihydroxyvitamin D.
Vitamin D (1,25-dihydroxyvitamin D) has multiple roles in the body as shown above. There are over 300 different binding sites for Vitamin D throughout the human genome with receptors present in all human tissues. The parathyroid glans in the neck secrete PTH to activate and regulate vitamin D.
- Risk factors for vitamin D deficiency include age>65, breastfeeding mothers, insufficient sunlight exposure, certain medications (anticonvulsants, steroids, others), obesity, physical inactivity, liver and kidney disease, and dark pigmented skin. Vitamin D deficiency was historically associated with rickets ( a bone disease)
Of course rickets is rare in the U.S. due to fortified foods.
- Studies are clear that vitamin D is important for health and prevention. There is an inverse association of 25-hydroxyvitamin D serum levels with risk of death due to cardiovascular disease and cancer. In other words, low vitamin D levels in the body are associated with higher cardiac events and higher risk of cancer!!
- Supplementation with vitamin D3 reduces overall mortality in older adults!
- Vitamin D deficiency is based on a blood level of less than 20 ng/mL of 25-hydroxy vitamin D. It appears that correcting vitamin D levels may be on par with health risks such as smoking, alcohol consumption, and physical inactivity!
- Based on calculations from one study, 12.8% of all deaths in the U.S. can be attributed to vitamin D deficiency. So for every 10 ng/ml decline in serum vitamin D, there appears to be a 16% increase in all cause mortality. Supplementing with vitamin D3 decreased all cause mortality by 11%. There appears to be no benefit or protection by supplementing with vitamin D2. Vitamin D2 is less potent and active than vitamin D3. It may be that calcium is needed to be used with vitamin D2 to be effective.
- You can obtain enough vitamin D by exposure to sunlight (UVB) for 15 minutes a day if you are light skinned. Dark skin requires up to an hour of exposure to create enough daily vitamin D. Our body produces vitamin D in the skin and does so at higher levels in the summer time. Obviously, in the winter time, we are at risk of deficiency due to less skin exposure. Sun block will prevent UVB from reaching our skin and therefore will prevent the skin from creating vitamin D.
- Vitamin D toxicity (levels greater than 150 ng/ml) result from high intake of vitamin D (greater than 10,000 units/day)
- The bottom line: Get your 600-800 IU of vitamin D3 every day. Vitamin D3 is the best form of vitamin D. Boosting your vitamin D levels can decrease your cardiac and cancer risks!
- http://www.vitamincouncil.org/ <–Vitamin D information!
- Chowdury R, et al Vitamin D and risk of cause of specific death. BMJ 2014;348:g1903.doi: 10.1136/bmj.g1903