We wrote about the association of low vitamin D levels and obesity awhile ago (Portsmouth Daily Times June 2010). Besides that association with obesity, the medical literature on vitamin D has exploded. Everybody is checking their vitamin D levels. Taking vitamin D supplements, no matter what their blood tests show, is rampant. I’m constantly having to defuse people who come to me because someone has found that their vitamin D levels are too low. Most recently there is a lot of equivocal stuff about how vitamin D levels might be related to COVID-19 and President Trump and Dr. Anthony Fauci are taking vitamin D supplements. In researching this article the flood of vitamin D stuff felt like being water-boarded.
Some basic background and the bottom line about vitamin D:
Vitamin D is technically not a vitamin since we can make it ourselves. It is more like a hormone. It is made in the skin because it requires sunshine. But it can be taken in from what you eat. Only a few foods, like fish, naturally contain much vitamin D so milk and other foods have been fortified with vitamin D in the US and everywhere forever. Since sunshine can cause skin cancer dietary recommendations for vitamin D assume that we will take it all in by mouth. Vitamin D from the diet or from the skin synthesis is inactive; it has to be converted to the active form by 2 steps, the first one in the liver and the second in the kidney, before it can do what it is supposed to do, which is mostly help you absorb calcium from your diet. Vitamin D is important for regulating calcium and phosphorus in the body especially in the bones and preventing rickets which is soft mushy bone disease in children – osteomalacia. It probably does other things too but the non-controversial evidence that taking vitamin D supplements in adulthood is good for anything is zilch.
One thing I found was that black Americans, as compared with whites, had low levels of total 25-hydroxyvitamin D and also low levels of vitamin D–binding protein, which carries the vitamin D in the blood. But they have similar concentrations of bioavailable 25-hydroxyvitamin D. Meaningless genetic differences explain this observation. So a million studies that show that blacks are vitamin D deficient can be flushed.
Finally, there is some relief from this vitamin D fad. There’s is growing expert advice to stop checking vitamin D levels because they just cause more grief than it’s worth. Thank you God. And don’t forget that vitamin D is a fat soluble vitamin and it is possible to overdose.
Powe CE et al. Vitamin D–Binding Protein and Vitamin D Status of Black Americans and White Americans N Engl J Med 2013; 369:1991-2000 DOI: 10.1056/NEJMoa1306357
Lucas A, Wolfe M. Vitamin D and Health Outcomes. Then Came the Randomized Clinical Trials JAMA. 2019;322(19):1866-1868. doi:10.1001/jama.2019.17302
Manson JAE et al. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. N Engl J Med 2019; 380:33-44 DOI: 10.1056/NEJMoa1809944
Powers BW, Jain SH, Shrank WH. De-adopting low-value care. viewpoint. JAMA October 27, 2020 324(16):1603-4.
This writer’s opinion is their own and not the opinion of this newspaper
John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- firstname.lastname@example.org or phone-354-6605.