Forgive me for rattling on about vitamin D, but it is VERY important. The latest news is even more important than usual, and it is notable for at least three reasons, maybe four, if we count the fact that Mother’s Day is fast approaching.
The most meaningful studies are designed as interventional trials, where people are divided into groups, each receiving different treatments, and then their responses analyzed statistically to determine if the treatment had any effect. This study was designed in that way, with women who were pregnant for 12 weeks or more randomly assigned to receive either 400, 2,000 or 4,000 iu of vitamin D a day. Researchers then tracked their risk of major complications of pregnancy, including premature labor, premature birth and infections. The highest dose of vitamin D, 4,000 iu/day, was clearly associated with the lowest rate of complications.
First, this is important because pregnancy complications are serious and common.
Secondly, because showing that doing something has an effect demonstrates cause not just association.
FInally, given official warnings that taking 2,000 iu/day of vitamin D is the safe upper limit, I am impressed that they were able to get the study approved. Human Subjects Committees at research institutions are mandated to block research that endangers the subjects of the trial. For example, 15 years ago, when I conducted the first national survey of alternative medical instruction in US medical schools and family practice residency programs, the Human Subjects Committee at UCSF refused to allow me to resend questionnaires to schools that did not respond to the first one, as they felt that I would be harming them by such a request. Seriously. Thankfully, the particular HSC involved in this case was courageous enough to approve this vitamin D study. As such research is needed and human subjects committee can be ridiculously conservative, this is not a minor event. I find that most patients need well more than the “safe limit” of 2,000 to bring their blood levels up to normal. This “safe limit” is completely wrong and unscientific. It must be changed, and the sooner the better.