Micronutrient requirements of the elderly

Decreased Need? Until quite recently, it was believed that with advancing age, there is a decreased need for certain vitamins such as thiamin, riboflavin, niacin, iron because of lower calorie and protein intakes, and for iron due to the lack of menstrual periods in elderly females. However, now there is increasing evidence to suggest that this is not correct. Increased Need for Vitamins D, B6 and B12 There is strong evidence that the elderly’s requirements for vitamin D, vitamin B6 and B12 actually increase with age. Vitamin D Many studies have shown that levels of the active form of vitamin D are lower in older people than in younger people. The reasons for this could be that older people ingest less vitamin D in their diet because they consume fewer dairy products. However, Webb et al(1) have shown that there is a decreased ability to form pre-vitamin D3 in skin, as a result of ultra violet light exposure in elderly people Vs young people. A large part of the vitamin D requirement is met by skin synthesis and not dietary ingestion of the vitamin and so impaired skin synthesis will result in a higher dietary need in the older person. Dawson-Hughes et al(2) recently studied the effect of vitamin D supplementation on bone mineralisation in healthy postmenopausal women. The study was a double-blind, placebo-controlled trial lasting for one year. The women were randomly assigned to receive either placebo or 400 iu of vitamin D daily. All were on their usual dietary intakes of vitamin D of 100 iu daily. The researchers found a net gain in both spine and whole body bone mineral density during the summer/autumn period and a net loss in the winter/spring period. There was also a net increase in the spinal bone mineral density in the vitamin D supplemented group Vs the placebo group. The conclusion reached was that healthy post-menopausal women who live at the geographical latitude 42 degrees, and who have a dietary intake of 100 iu vitamin D daily, could reduce their winter bone loss and improve spinal bone density over a one year period by supplementing themselves with 400 iu of vitamin D each day. This is particularly true of elderly people who cannot or prefer not to expose themselves to sunlight as well as those living in northern latitudes. Vitamin B6 Many elderly populations have been found to have low levels of vitamin B6. In one Dutch study,(3) 10 per cent of those aged 65 or over were found to be deficient in this nutrient. Vitamin B12 Vitamin B12 requirements may be increased in a large number of elderly people suffering from atrophic gastritis, an age-related stomach condition that results in less acid and pepsin secretion. In the USA, 25% of elderly persons aged 60 – 69 and almost 40% over 80 years old have atrophic gastritis. This disorder may cause problems in vitamin B12 absorption either because of impaired digestion of cobalamin from food protein (due to the lack of acid pepsin digestion) as well as to bacterial uptake of vitamin B12 in the small intestine (due to the lack of acid to kill swallowed bacteria). Vitamin A There is some evidence to suggest that there is a lower requirement for vitamin A for the elderly than for younger people. Krasinski et al(4) have recently shown that this may not be due to increased absorption of the vitamin, but rather to its less efficient excretion by hepatic (liver) and other peripheral tissues. They found that the rate of vitamin A clearance from the blood was twice as fast in younger people as in the elderly. Minerals, Vitamin E and Vitamin C There is no clear evidence that mineral requirements are any different for elderly individuals as compared with younger individuals. The only exception is that post-menopausal females have lower iron requirements. Vitamin C needs are higher for older people than the current recommended daily allowance (NRV) which is 60mg. They need at least 125mg daily to reduce the chances of developing a cataract by four-fold. Ames et al(5) have recently shown that ascorbate is the most effective anti-oxidant in human blood and may be important in protecting against oxidant stress-related diseases and degeneration. So, to maintain tissue levels at full saturation may be desirable not only for the elderly, but throughout the life span, since many of the chronic diseases may have started years earlier. Conclusion Our knowledge of vitamin and mineral requirements of the elderly is continually evolving. What can be said is that not all vitamin and mineral requirements stay static over the adult life span. Each micronutrient needs to be examined individually and from this, specific recommendations will develop. References 1. Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D3. J Clin. Endocrinol Meta b1988;67;373-8 2. Dawson-Hughes B, Dallal GE, Krall EA, Harris S, Sokall LJ, Falconer G. Effect of vitamin D supplementation in winter time and overall bone loss in healthy postmenopausal women. Ann Intern Med 1991;115;505-12 3. Tolonen M, Schrijver J, Westermarck T, Halme M, Tuominen SEJ, Frilander A, Keinonen, Sarna S. Vitamin B6 status of Finnish elderly, comparison with Dutch younger adults and elderly. The effect of supplementation. Int J Vitam Nutr Res.1988;58;73-7 4. Kraskinski SD, Cohn JS, Schaefer EJ, Russell RM. Postprandial plasma retinyl ester response is greater in older subjects compared with young subjects. J Clin Invest 1990;85;883-92 5. Balz F, Stocker R, Ames BN. Anti-oxidant defence and lipid peroxidation in human blood plasma. Proc Natl Acad Sci SA 1988;85;9478-52.