Vitamin D – D or Solar Hormone

Vitamin D

What is Vitamin D?

Vitamin D (VD) is also called as D or solar hormone. It has an important role in the development, growth, and maintenance of a healthy body from birth to death. Mankind needs sun exposure for vitamin D requirements in life. Season, latitude, daytime, skin pigmentation, aging, customary clothing, sunscreen, glass, obesity have an effect on the production of vitamin D. Vitamin D is important for calcium absorption from the bowel. The avoidance of sun exposure increases vitamin D deficiency risk.

Vitamin D Deficiency and Recommended Daily Intakes of Vitamin D

Vitamin D is metabolized in the liver and then in the kidney to 1.25-dihydroxyvitamin D [1.25(OH)2D]. 1.25(OH)2D receptors are presented in the intestine and bone. These receptors are settled in other tissues such as the brain, heart, stomach, pancreas. Vitamin D deficiency is a major unrecognized health problem. It is caused rickets in children. Also, osteomalacia and osteoporosis are observed in adults. Moreover, chronic vitamin D deficiency may give serious adverse consequences such as hypertension, multiple sclerosis, rheumatoid arthritis, cardiovascular disease, metabolic syndrome, cancers, breast, prostate, ovary, and diabetes.

Vitamin D deficiency can be correlated with accelerated aging and longevity of the life span. The levels below 20 ng/mL of VD defines vitamin deficiency. Monitoring of serum 25OHD3 concentrations can help reveal of vitamin D deficiencies. Sensible sun exposure prevents vitamin D deficiency (10-20 minutes for the arms, 3-4 times for legs and face a week).  The recommendation of daily intakes of vitamin D 1000 IU or 2000 IU is reasonable approaches to guarantee vitamin D sufficiency. Table 1 shows recommended amount of vitamin D per day.

  Table. 1 Recommended amount of vitamin D per day

Age Recommended amount of vitamin D per day:
0 to 1 year 400 IU
1 to 70 years 600 IU
Over 70 years 800 IU

Great Sources of Vitamin D

The major source of vitamin D for children and adults is natural sunlight. Thus, the major cause of vitamin D deficiency is inadequate exposure to sunlight. Wearing a sunscreen with a sun protection factor of 30 reduces vitamin D synthesis in the skin by more than 95%. Some foods are fortified as sources of vitamin D (Table 2).

Table. 2 Food Sources of Vitamin D

Food Serving Size Amount of Vitamin D
Salmon, Atlantic, cooked 75 g 246 IU
Salmon, chum, canned 75 g 202 IU
Tuna, yellowfin, cooked 75 g 105 IU
Milk 250 mL 104 IU
Tuna, canned, light 75 g 36 IU
Egg yolk 1 egg 32 IU



De Luca HF, Cantorna MT. Vitamin D: its role and uses in immunology. FASEB J 2001; 15:2579-85.

Holick, M. F. (2003) Vitamin D: A Millenium Perspective. Journal of Cellular Biochemistry, 88:296–307

Hossein-nezhad, A., Holick, M. F. (2013). Vitamin D for Health: A Global Perspective.  Mayo Clin Proc. 88(7):720-755

Norman AW. Receptors for 1,25(OH)2D3: past, present, and future. J Bone Miner Res 1998; 13:1360-9.

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