Population at risk of low serum vitamin D levels

Normal serum vitamin D level is the range between 30-100 ng/mL, but this value can vary among laboratories. Vitamin D deficiency and insufficiency have been defined as a 25 (OH)D < 20 ng/mL and 21-29 ng/ mL, respectively.

Some groups of the population are at greater risk of low serum vitamin D deficiency which may need daily vitamin D supplementation. They are the following:

• Infants and young children aged six months to five years old

• Pregnant and breastfeeding women

• Postmenopausal women

• Elderly people aged > 65

• People who have limited sun exposure - for example, those who always cover their skin, or are not exposed to much sun or stay indoors for long periods or regularly apply sunscreens

• People with darker skin

Low vitamin D can cause rickets (thin, brittle, or deformed bones) in children and osteomalacia (softening bones) in adults. Adequate vitamin D and calcium intake help protect older adults from osteoporosis. Vitamin D obtained from sunlight or food never causes vitamin D toxicity (high blood calcium). On the contrary, too much vitamin D supplementation can cause toxicity.