Vitamin D deficiency and insufficiency is a Global health problem. The Institute of Medicine has recommended for maximum calcium and bone health that a blood level of 25-hydroxyvitamin D should be at least 20 ng/mL (50 nmol per liter). The Endocrine Society defined vitamin D deficiency as a 25-hydroxyvitamin D <20 ng/mL, insufficiency 21-29 ng/mL and sufficiency of 30 ng/mL-100 ng/mL. Toxicity is not observed until blood levels are above 150 ng/mL. The IOM recommends to satisfy the vitamin D requirement infants require 400 IUs daily, children 1 year and older and adults up to age 70 years 600 IUs daily and adults >70 years 800 IUs daily. The Endocrine Society recommends for infants 400-600 IUs daily, children 1 year and older 600-1000 IUs daily and all adults 1500-2000 IUs daily. For those who have a BMI >30 they require 2-3 times more vitamin D to satisfy their requirement. Globally 40% of children and adults are considered to be vitamin D deficient and an additional 20% insufficient. Vitamin D deficiency causes rickets in children and osteoporosis and osteomalacia in adults. It also is associated with muscle weakness and increased risk for falling. Very few foods naturally contain vitamin D but in some countries vitamin D fortification is practiced and has been for beneficial for improving the vitamin D status of children and adults. Sunlight is a major source of vitamin D. Time of day, season, latitude, altitude, weather conditions and skin pigmentation all influence the cutaneous production of vitamin D. The app dminder.info provides guidance for how much vitamin D can be made and also provides a warning that enough sun exposure has occurred and that sun protection should be employed to prevent damaging effects from excessive sun exposure.

It is now recognized that almost all tissues and cells in the body have a vitamin D receptor.  In addition many cells in the body also have the capacity to convert 25-hydroxyvitamin D to 1,25-dihydroxyvitamin D.  There are a multitude of studies associating inadequate sun exposure and vitamin D deficiency with many chronic illnesses including multiple sclerosis, rheumatoid arthritis, type 1 diabetes, cardiovascular disease, neurocognitive dysfunction, infectious diseases and many deadly cancers.  Improving vitamin D status has been reported to reduce risk of type 1 diabetes, improve cardiovascular health in teenagers, reduce risk of influenza A infection in children, reduce risk of upper respiratory tract infections in adults reduce risk for type 2 diabetes, cardiovascular disease, breast, prostate and colon cancer in adults.  It is now recognized that vitamin D plays an important role in immune modulation.  We have conducted studies for up to 6 months evaluating various doses of vitamin D of up to 10,000 IUs daily and have reported marked improvement in the expression of more than 1000 genes associated with more than 80 different metabolic processes.  There is mounting evidence that the improvement in vitamin D status can reduce risk for morbidity and mortality associated with COVID 19.  Therefore improvement in everyone’s vitamin D status could have a dramatic effect on improving their overall health and welfare.