Vitamin D Revisited

Dr. Leslie Kernisan reprized an article on Vitamin D supplementation this weekend. The one finding worth noting is that simply spending time outdoors is no guarantee that you have a sufficient amount of this vitamin in your body. I’ll explain below:


  • Source: Vitamin D occurs naturally and can be created and activated by the body through a three-step process starting with synthesis from exposure of skin to sunlight, and then two hydroxylation actions first in the liver and then in the kidneys. It can also be captured from dietary supplements.
  • Known benefits of vitamin D: The body uses vitamin D for several purposes:
    • Bone creation and to limit the risk of brittle, soft or deformed bones. The related disease conditions are rickets in children, osteomalacia in adults, and osteoporosis among older adults.
    • Prevention of involuntary muscle spasms or cramps
    • Maintenance of calcium and phosphate concentrations at the right levels in the blood stream
    • Reduction of inflammation and moderation of cell growth, neuromuscular and immune function, and glucose metabolism(1)
  • Other benefits under study:
    • Reduction in fall risk among older adults
    • Reduction in the risk of developing MS
    • Improving mood and mediating depression
    • Supporting the immune system(2)
  • Risks associated with vitamin D
    • No maximum safe dosage has been identified.
    • The appropriate dose to maintain proper blood serum chemical levels will vary with age.
    • Dr. Kernisan cites one study showing an increased fall risk at an extremely high dose level (500,000 IUs administered once per year)
  • Recommended supplement levels: based on a 2010 report from the American Academy of Medicine, 600 IUs per day for children and adults up to age 70, and between 800 and 1,000 IUs per day for older adults.

Synthesis of vitamin B in the body requires exposure to IVB sunlight wavelengths. That exposure can be reduced by several factors:

  • Time of day, with lower levels of these rays in the early morning and late afternoon
  • Use of sunscreen (needed to protect against melanoma)
  • Clouds and smog

In other words, you can live in the Las Vegas desert and be vitamin D deficient. The air quality is that bad.



Finally, Happy Father’s Day and Happy Juneteenth!


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