Vitamin D and aging

Abstract

Age-related changes affect vitamin D metabolism and increase the requirement for vitamin D in the elderly. Also there is an age related decrease in calcium absorption and a higher calcium intake is needed. Increasing calcium from dietary sources may be better than supplements, and requires increasing the intake of dairy products or other and calcium-fortified foods. Evidence suggests that vitamin D and calcium nutrition can be improved in the elderly by increasing the vitamin D intake to 800 IU daily together with a total calcium intake of 1000 mg daily. This combination is a simple, inexpensive strategy that can reduce fractures in institutionalized individuals by 30%.

Fig. 1

Vitamin D metabolism.

Fig. 2

Calcium absorption is lower in elderly (red) compared with young (yellow) women for any given serum 1,25 dihydroxyvitamin D level. (Data from Kinyamu HK, Gallagher JC, Prahl JM, et al. Association between intestinal vitamin D receptor, calcium absorption, and serum 1,25(OH)₂D in normal young and elderly women. J Bone Miner Res 1996;11:1400–5.)

Fig. 3

Decreased renal production of serum 1,25(OH)₂D with age after PTH stimulation.

Fig. 4

Serum 1,25(OH)₂D levels in women of different ages. (Data from Kinyamu HK, Gallagher JC, Balhorn KE, et al. Serum vitamin D metabolites and calcium absorption in normal and elderly free-living women and in women in nursing homes. Am J Clin Nutr 1997;65:790–7.)

Fig. 5

Dose response of vitamin D on serum 25OHD.