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Perspectives

Vitamin D deficiency: making a clinical difference

Phillip Clifton-Bligh

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Abstract

Vitamin D deficiency can be caused by a lack of exposure to sunlight, increased skin pigmentation and veiling. Supplementation is the best way to reduce the consequences of this deficiency.

Key Points

  • Despite plentiful sunlight, many people have low levels of vitamin D; older people in aged care and veiled women and their newborn babies are at particular risk of deficiency.
  • The best marker of vitamin D status is serum 25-hydroxy (OH) vitamin D levels. There is evidence to suggest the levels of serum 25-OH vitamin D should be more than 75 nmol/L for optimal health.
  • 1,25-dihydroxy [(OH)2] vitamin D, formed from 25-OH vitamin D, enhances absorption of calcium and phosphate across the upper gastrointestinal tract.
  • When the level of serum 25-OH vitamin D is less than 30 nmol/L in neonates, there is an increased risk of developing rickets.
  • Due to the low level of 25-OH vitamin D in human breastmilk, mothers who breastfeed should take a supplement of 4000 IU/day of vitamin D.
  • In older persons, vitamin D supplementation to raise 25-OH vitamin D levels above 75 nmol/L reduces the risk of falling and fracture and may reduce all-cause mortality.

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