There’s been multiple news reports lately regarding vitamin D and its benefit on everything from Alzheimer’s to heart disease to extending life. Before getting into these claims, let’s take just a minute to review how the body makes vitamin D.
When UVB ultraviolet light hits your skin, it converts a particular type of cholesterol to pre-vitamin D3. This in turn is converted by body heat into vitamin D3. This in turn is converted by the liver into 25-0H vitamin D which is the biologically active form. Hence, those that are deficient in the particular type of cholesterol (the elderly) or have minimal sun exposure or completely cover with sunblock or have dark skin can have lower vitamin D levels. Having low levels of vitamin D correlates most accurately with poor bone health, particularly osteomalacia and osteoporosis, leading to multiple bone fractures (think rickets in children and fractured hips and backs in the elderly).
The latest research is investigating vitamin D supplements for:
- Preserving chromosome telomer length, hence extending lifespan.
- Improving muscle strength
- Improving immunity to infections
- Lowering cancer incidence, particularly colon cancer
- Prevention of diabetes and improving blood sugar control
- Prevention atherosclerotic heart disease and improving control of blood pressure
- Preventing Alzheimer’s
Up-to-Date, a major reference for doctors, reviewed 206 different scientific papers and found taking vitamin D for the above claims inconclusive except for bone health and colon cancer.
In summary, a vitamin D blood level (easily tested by your doctor) above 30 but less than 50 is optimal. If you do want to take a supplement, 1000 to 2000 international units (IU) of vitamin D3 daily is safe, but it is unknown how helpful it may be.
Dr. Charlie Barnett is a contributor at KnoxTNToday for a weekly column, DocTalk, providing his expertise on health and wellness management.
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