Re: Vitamin D and falls: The burden of proof
The benefits of vitamin D for bone and muscle strength and its multiple other extra skeletal advantages are one of the major medical breakthroughs of the past decade. Yet, we continue to see new trials and meta-analyses trying to cast doubts on this important nutrient that works as a hormone on all the systems of the body. One of the examples of controversial studies quoted by this article is a study by Heike A. Bischoff-Ferrari, MD and et al starts without any working hypothesis and ends with the statement that "the physiology behind a possible detrimental effect of a high monthly bolus dose of vitamin D on muscle function and falls remains unclear and needs further investigation.
Reviewing the full study protocol of the above study, the weak foundation and the design flaws of this study are on full display. The following disorders and drugs must be exclusion criteria for every trial or meta- analysis: hypertension, hyperlipidemia and diseases of autonomic nervous system (or drugs affecting this system). Statins are commonly used in geriatric population with major detrimental effect on the proximal muscles of the lower extremities predisposing such patients to falls. Diuretics, vasodilators, including alpha blockers, nitrates, drugs for benign prostate hypertrophy, drugs used in erectile dysfunction, widely used anti-cholinergic medications, and anti-histamines (including anti-depressants and drugs for overactive bladder) must be all in exclusion criteria. Diabetes must also be included as exclusion criteria. Most patients with advanced type 1 or type 2 diabetes do have a certain degree of autonomic dysfunction, which includes orthostatic hypotension, a major risk factor for falls. Uncontrolled diabetes causes volume depletion and osthostasis and increases the risk of falls. The new-generation of anti-diabetes drugs such as canagliflozin, causes volume depletion and increases risk of falls. Past and present use of steroids, with known detrimental effects on the proximal muscles of the legs such as the quadriceps, must be also an exclusion criterion. Vitamin D supplements strengthen the musculo-skeletal system especially the proximal muscles of the lower extremities. This is a clear clinical outcome that we see daily in our practice. I have taken hundreds of frail elderly with proximal myopathy off walkers and prevented falls by judicious supplemtation of vitamin D. The opposite claim, that vitamin D increases falls or has no effect on falls, does not have a plausible biological explanation. In my opinion, most studies, if not all, similar to this study, fail to show the benefit of vitamin D on falls, do so because they have serious design flaws; mostly neglecting very important exclusion criteria.
Monthly High-Dose Vitamin D Treatment for the Prevention of Functional Decline. Bischoff-Ferrari, HA et al. JAMA Intern Med. 2016;176(2)
Competing interests: No competing interests