Question

In the absence of ultraviolet rays reaching the earth, humans would suffer from the deficiency of

• A. Fatty acids
• B. Essential amino acids
• C. Vitamin D
• D. Vitamin E

Answer 1

Answer: (C)

In the absence of ultraviolet rays reaching the earth, humans would suffer from the deficiency of vitamin D.

Vitamin D refers to a group of fat-soluble secosteroids responsible for enhancing intestinal absorption of calcium, iron, magnesium, phosphate and zinc.

Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis from sunlight is biologically inactive, activation requires enzymatic conversion (hydroxylation) in the liver and kidney. Evidence indicates the synthesis of vitamin D from sun exposure is regulated by a negative feedback loop that prevents toxicity, but because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine (US), for the amount of sun exposure required to meet vitamin D requirements.