Vitamin D plays an important role in bone health, heart health and immune support while working with vitamin K to promote proper utilization of calcium and promote healthy arteries.

Technically not a "vitamin," vitamin D is in a class by itself. Its metabolic product, calcitriol, is actually a secosteroid hormone that targets over 2000 genes (about 10% of the human genome) in the human body. Current research has implicated vitamin D deficiency as a major factor in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more.

Vitamin D's influence on key biological functions vital to one's health and well-being mandates that vitamin D no longer be ignored by individuals striving to achieve and maintain a greater state of health.

If well adults and adolescents regularly avoid sunlight exposure, research indicates a necessity to supplement with at least 5,000 units (IU) of vitamin D daily. To obtain this amount from milk one would need to consume 50 glasses.

The skin produces approximately 10,000 IU vitamin D in response 20-30 minutes summer sun exposure-50 times more than the US government's recommendation of 200 IU per day! Of course, if you use sun block, you also block the Vitamin D production.

People who live in the northwest just cannot get enough sun to supply a year-round need for Vitamin D. And as a general rule, old people need more than young people, dark-skinned people need more than light-skinned people, and sick people need more than healthy people.

More information and study results are released every month as more is learned about this very important nutrient. It is important to your health to look into whatever condition, illness or symptoms you may have to see what research is finding out about the link to Vitamin D.

• Michael F Holick. High Prevalence of Vitamin D Inadequacy and Implications for Health. The purposes of this article are to examine the prevalence of vitamin D inadequacy and to review the potential implications for skeletal and extraskeletal health.
• Armin Zittermann. Vitamin D in preventive medicine: Are we ignoring the evidence? Zittermann reviews the numerous illnesses associated with vitamin D deficiency and the evidence those illnesses are helped by vitamin D.
• Michael F Holick. Vitamin D: A Millenium perspective. Holick reviews the biology of vitamin D and the extent of the problem of vitamin D deficiency.
• Reinhold Vieth. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Vieth started it all with this masterful paper on the unwarranted fear (bordering on hysteria) of vitamin D toxicity.