sunshine (1)“The sun to rule by day: for his mercy endureth for ever” Psalm 136:8

Nicely summarized, sunshine is health and happiness

The benefits of the exposure to sunlight are generally focused on vitamin D. However, the effects of the sun extend beyond its vitamin D connection. In addition to the synthesis of vitamin D sunlight causes you to feel more energetic, active, less nervous, strengthened, and balanced.  Many people can identify with the low-sunlight, winter depression symptoms of fatigue, lowered motivation, sleepiness, increased appetite, weight gain, irritability, and decreased sociability.

The truth is the therapeutic effects from the sunlight are much broader than the simple synthesis of this important substance.  For example, the connection between sunlight and our well being is through the increased production of the feel-good brain chemical, serotonin.   Motion of the sun, perceived through our eyes, from sunrise to sunset, sets our biological clock and determines our circadian rhythms.  Much is yet to be unraveled about the mysteries and miracles of sunshine.  However, for this moment let’s focus on vitamin D.

The “Vitamin D” Connection

The main function of vitamin D is to maintain the body’s calcium concentrations at a precise level.  This is accomplished by increasing the absorption of calcium from the intestines and the interaction with other hormones (like parathyroid hormone).   Almost all tissues and cells in the body have receptors for this hormone, and therefore are affected by its presence.

More than 90% of the vitamin D requirement of people is met by internal synthesis with the aid of sunlight, not from the diet.4 Very few foods naturally contain vitamin D.  Examples are: fatty marine fish (salmon, cod liver oil, mackerel, and  sardines); and a few foods are fortified with vitamin D, like cow’s milk sold in the United States, as well as some orange juices, cereals, and breads – the vitamin is added during manufacturing.  Vitamin supplements (pills) are also common sources of this active substance.

Although vitamin D is best known for its role in strengthening bone and preventing rickets, it is increasingly apparent that it may have beneficial health effects beyond the skeletal system, among them perhaps the prevention of a number of diseases, including cancer (1). These health effects have been the focus of two recent National Institutes of Health–sponsored conferences (2,3) and a number of reviews (46).

1) Lappe JM, Travers-Gustafson DT, Davies KM, Recker RR, Heaney RP. Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial. Am J Clin Nutr (2007) 85:1566–91.
(2) Davis CD, Hartmuller V, Freedman DM, Hartge P, Picciano MF, Swanson CA, et al. Vitamin D and cancer: current dilemmas and future needs. Nutr Rev (2007) 65:S71–4.[CrossRef][ISI][Medline]
(3) Raiten DJ, Picciano MF. Vitamin D and health in the 21st century: bone and beyond. Am J Clin Nutr (2004) 80:1673S–77S.[Abstract/Free Full Text]
(4) Holick MF. Vitamin D deficiency. New Engl J Med (2007) 357:266–81.[Free Full Text]
(5) Bikle DD. What is new in vitamin D: 2006–2007. Curr Opin Rheumatol (2007) 19:383–8.[CrossRef][ISI][Medline]
(6) Mullin GE, Dobs A. Vitamin D and its role in cancer and immunity: a prescription for sunlight. Nutr Clin Pract (2007) 22:305–22.[Abstract/Free Full Text]