In the United States, milk is often fortified with vitamin D, which many believe also lends the drink bone-friendly properties. But the evidence behind this assumption is sketchy as well. It is true that vitamin D is necessary for calcium absorption, and for bone health, but that doesn’t mean that most people need to consume more. A meta-analysis published this year in The Lancet examined the effect of vitamin D supplementation on bone mineral density in middle-aged and older adults. It found that, for the most part, consuming extra vitamin D did not improve the bones of the spine, hip or forearm. It did result in a statistically significant, but less clinically meaningful, increase in bone density at the top of the thighbone. Taken as a whole, however, vitamin D had no effect on overall total body bone mineral density.