Vitamin D supplementation during pregnancy: state of the evidence from a systematic review of randomised trials

Dr. Roth accurately writes that randomized controlled trials (RCTs) of vitamin D in pregnancy have shown conflicting results. He also gives a number of reasons that may explain those negative trials. And, like a competent scientist, he opines that until RCTs show efficacy without toxicity, physiological doses of vitamin D should not be prescribed in pregnancy. Instead we should continue with the near homeopathic doses (10 – 15 mcg/day) that are now used in pregnancy. ( I can't think of any other nutrient used in such meaningless doses but I'm sure they exist.)

However, if his standard were followed, we would not treat scurvy with vitamin C, prevent beriberi with thiamine, pellagra with niacin, or help prevent neural tube defects with folic acid, none of which have RCTs supporting such use. Physicians of the past addressed the pathological consequences of the inadequate intake of nutrients, not with more RCTs, but by applying common sense.

Yesterday (11/29/17), yet another study (four to date) confirmed low levels of vitamin D during pregnancy are associated with a substantially increased risk of developing autism. (1) Almost ten years ago the vitamin D/autism link exposed in detail (2), ten years during which time 134 additional such papers appeared and during which time hundreds of thousands children were condemned to autism. Similar, but fewer, studies exist for the substantial risk of developing multiple sclerosis in later life as well as most of the diseases of pregnancy. As Dr. Roth points out, the results of most of those studies were mixed. What he did not dwell on is the fact that "the dose makes the medicine." and the doses in almost all the studies he reviewed used 10 or 15 mcg/day, a dose that often does not result in meaningful changes in vitamin D status levels nor in preventing disease, (It is instructional to stop using IUs to measure the mass of vitamin D and move to the metric system. For example, 250 mcg is considered a small dose by many, while 10,000 IU is a large one without knowing they are the same dose.)

Two crucial points are missed with Roth's opinion. The first is that vitamin D is safe. If you think it dangerous at physiological adult doses (125-250 mcg/day), you are ignorant about its toxicology. ( “Everything is toxic, nothing is without toxicity, the dose alone determines if something is toxic.) Since it is safe at these doses, one has to weigh the consequences of action vs. the inaction Dr. Roth advises. It seems to me, common sense dictates pregnant women should be supplemented now, not made the Guinea pigs of further RCTs.

Finally, there are stark differences between scientists and physicians. Scientists require definitive proof before a theorem is considered fact. In other words, beyond a reasonable doubt. But scientists do not treat patients, with few notable exceptions. Scientists do not take the Hippocratic Oath. The standard physicians used over history was to balance the known toxicity with the potential benefits and act accordingly. Physicians should ask their attorney if such a standard of treatment still exists and if they may the be held to it in a courtroom.

Physicians have never required endless RCT for proof until very recently with the onset and misunderstanding of Evidence Based Medicine. Instead physicians have always, until recently, weighed the potential consequences of treatment vs. inaction, that is potential harm vs. potential benefit. If you weigh on the potential harm call for inaction side, you are reading a different vitamin D literature (now at 61,323 publications) than I am reading.

Physicians are required by law and ethics to act on the evidence known today, not what may be discovered in the future. If inaction persists, what are we going to say to parents of the children with autism or the women who develop MS in the future? “Oh, I’m so sorry your child has autism but we decided to let scientists determine physician’s action instead medical tradition or common sense.”

1. Basheer S, et al. Vitamin D status of children with Autism Spectrum Disorder: Case-control study from India. Asian J Psychiatr. 2017 Dec;30:200-201.

2.Cannell J.J. Autism and vitamin D. Med Hypotheses. 2008;70(4):750-9.