Vitamin D is widely recognized as a critical component to human health. The breadth of its importance is well-documented by Michael F. Holick, PhD, MD,1 a leading expert in vitamin D research, who wrote in the consumer press that if he could name one single “secret ingredient” to prevent and in many cases treat ailments including: heart disease, common cancers, stroke, types 1 and 2 diabetes, dementia, depression, insomnia, muscle weakness, joint pain, osteoporosis, psoriasis and hypertension, among others, it would be vitamin D. Holick’s findings are profound and encapsulated in his simple statement: “With adequate levels of vitamin D, you will live longer.” Table 1 summarizes some of the benefits of vitamin D he has found.
Considerable debate exists in the scientific community as to the minimum level of vitamin D necessary to optimize human health. The US Department of Agriculture’s (USDA’s) daily recommendation for vitamin D was increased from 400 to 600 IUs (international units) late in 2011.2 This amount is challenged by Holick and other health professionals who recommend a minimum of 1,000 IUs daily.3 In fact, according to a recent study in the Archives of Internal Medicine, 75% of Americans do not get enough vitamin D.4
