The authors of the study on calcium and vitamin D supplementation as they relate to fractures were all orthopedic surgeons, as stated in the paper. They had no known training in nutrition. Maybe not statistics either.
When you perform a meta-analysis, each research study included is given a weight in the form of a percentage, which indicates how much it contributed to the outcome. Not all studies should contribute equally; that helps to eliminate the bias of a tremendous benefit in a very small study versus a large study with no benefit. They didn’t seem to read something in three studies that contributed close to 90% of the analysis (2-4): the authors of those papers said that the reduction in fractures did occur, or at least bone was restored, when the subjects took over 80% of the doses of calcium and vitamin D they were supposed to take. The problem: average compliance was around 50%.
What these surgeons could have done was tease out the data on those subjects who were compliant and analyzed that data. What they might have had were results that demonstrated that in order to get a benefit, subjects had to take the supplements regularly. That would have been meaningful. Instead, inexperience or ignorance left us with headlines but little else.
Still, there are some questions that were raised in my mind and I’ll cover them on Saturday. But one thing won’t change: if you’re going to take supplements of any kind, you’ve got to actually take them if you want a benefit.
What are you prepared to do today?
1. JAMA. 2017;318(24):2466-2482. doi:10.1001/jama.2017.19344.
2. Lancet. 2005;365(9471): 1621-1628.
3. Arch Intern Med. 2006;166(8):869-875.
4. Am J Med. 2006;119(9):777-785.