If there is a vitamin supplement popular enough to be called ‘hot’, then vitamin D is surely the one. Sales of the sunshine vitamin have exploded over the last decade, fueled by both fears of a deficiency, and reports of its beneficial effects on a range of serious health conditions. But how much is true? While it’s universally acknowledged that vitamin D is beneficial for bone density, there is wide disagreement over its impact in other areas of human health. The Institute of Medicine, an independent, nonprofit organization connected to the National Academy of Sciences, took up the issue of vitamin D, as well as calcium, reviewing nearly 1,000 published studies as well as testimony from scientists and other experts. Sue Shapses, a Rutgers professor in the Department of Nutritional Sciences, served on the committee that conducted the study. The final report was issued recently and contained some surprising conclusions. Shapses, widely known for her research in osteoporosis, bone metabolism, and obesity, spoke to Rutgers Today about the findings.
Shapses: The last report was in 1997, and during that time there has been mounting evidence and a lot of controversy about what are the correct intake and appropriate levels of vitamin D. The committee wanted to have a Recommended Dietary Allowance or RDA for calcium and an updated RDA for Vitamin D because of all the information and articles out there. The report shows that nearly everyone requires 600 IU (international units) of Vitamin D per day and persons older than 70 require 800 IU per day.
Rutgers Today: The report found that the majority of Americans and Canadians are getting enough vitamin D and calcium. Prior to this study, was that fact ever in serious doubt among consumers, or the medical community?
Shapses: Yes. There were a number of reports that the prevalence of vitamin D deficiency was alarming. The committee came in looking to examine whether there was a deficiency and how big of a problem it was. We concluded we don’t have evidence now to support higher levels of intake. It doesn’t mean that evidence won’t show up in the future. But right now we can’t tell Americans and Canadians you have to be at higher levels when there is no evidence to support it.
Rutgers Today: Some say too much Vitamin D can have an adverse impact, while others say higher levels are needed for optimal health. Is there validity for either claim?
Shapses: The problem is we only have observational studies and we do not want to suggest higher nutrient intake unless we can be certain that there is a benefit as well as no risk. Observational studies can only examine associations and not the cause. In the past, vitamin E was believed to prevent heart disease based on observational studies, yet when the randomized trials were done, the benefit disappeared. A blood level for vitamin D at 20 ng/ml is needed for good bone health, and whether high levels are important for other outcomes requires randomized control testing.
Rutgers Today: What conclusion can the average health-conscious consumer take from this report?
Shapses: They can feel pretty confident that they have the proper blood levels for their bones without taking additional food or supplements. There are, however, a couple of groups that need additional intake. The older population may require supplements because their calorie intake typically goes down with age, causing lower nutrient intake too. Importantly, adolescent girls are not consuming enough total calcium or vitamin D possibly due to the belief they need to be restricting dairy foods. However, if teens consumed diets that were high in low-fat dairy they would be consuming a diet low in calories but nutrient rich. The best food sources of vitamin D are fatty fish, milk, mushrooms, eggs and meat, and the best calcium sources are dairy foods, almonds, kale, broccoli, oranges, and some fortified cereals, juices and tofu.