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.
- 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.