Nutrient Based Dietary Guidelines for Older People

By Robert M Russell, MD

Up until the late 19th century, about 50% of all persons died while giving birth or in infancy, and people did not generally live long enough to become at risk for contracting chronic non-communicable diseases, such as cardiovascular disease and cancer, which are characteristic of middle and old age. Before the 20th century, human mortality was caused primarily by starvation, infections, and trauma. However, in the 20th century, there has come about a shift in the causes of disease mortality in many countries, which has been termed an "epidemiologic transition." Indeed, in certain areas of the world, this has been more like an "epidemiologic revolution". This change has been especially apparent in Europe and North America. In these developed areas of the world, the increasing number of people with chronic non-communicable diseases is not just the result of decreasing mortality rates but also, in part, because of improved medical care and improved public sanitation. Even in countries with emerging economies, the rise in numbers of people with chronic non-communicable diseases is apparent, since decreased child mortality and the resulting increase in life expectancy allows more people to reach late-middle and old age - the ages at which chronic non-communicable diseases arise.

Thus, prevention of chronic disease is not only an issue of developed countries but is also increasingly becoming an issue for developing countries, and should be of concern to health agencies in countries throughout the world. For example, the growth in colon cancer rate is projected to be greatest in the formerly socialist countries of Europe.¹ The death rate from colon cancer is projected to grow in the 1990s by 1.2% in countries with established market economics, whereas death rates from colon cancer in Eastern European countries is expected to grow by 6.5%. Since nutrition can play a role in the prevention of such chronic non-communicable diseases, the provision of adequate nutrients to people as they age should be among the foremost concerns of health planners.

With the rise in importance of non-communicable diseases, scientists have begun to look at the contribution of nutrition in the prevention of diseases that are associated with the ageing process. It has long been known that older people are at an increased risk for developing nutrient deficiencies, although nutritional assessment of older populations is complicated due to: 1) problems in defining appropriate population samples that represent the various strata of older persons; 2) limitations of food intake assessment methods in older populations; and 3) the paucity of metabolic studies that have been performed directly on older people. The first two issues remain problematic, but over the last 15 years much has been learned about the nutritional requirements of older persons as well as the relationship between nutrients and the chronic diseases, which diminish the quality of life and life expectancy of older people.

Examples of nutrients that have been studied specifically in older people are riboflavin and vitamin B6. It had previously been thought that riboflavin requirements would be lower in older people as compared to younger people, because riboflavin is metabolically tied to energy expenditure, and older people expend less energy than younger people. However, in a recently performed depletion-repletion experiment on older people, it was found that riboflavin requirements were the same in older people as compared to younger people.² It should be noted that riboflavin intakes have been linked to at least one chronic non-communicable disease, esophageal cancer. In Linxing, China, the incidence of this cancer is 100 times that of the United States and Western Europe, and 95% of people in this region have riboflavin deficiency as defined by blood-testing (elevated erythrocyte glutathione reductase coefficient). In a Chinese intervention study that used a riboflavin and niacin supplement, esophageal cancer incidences and mortality over a 6-8 year period dropped significantly. Thus, in this region of China, meeting the riboflavin requirement could be an important factor to reduce the burden of this chronic disease.

In contrast, vitamin B6 requirement was previously thought to be the same in older people as in younger people; however, recent studies performed in elderly people have shown that the vitamin B6 requirement is increased with advancing age, although the reasons for this finding is uncertain.³ In one study, it was found that when an older person is vitamin B6-depleted, interleukin II levels drop significantly.⁴ Thus, deficiency of vitamin B6 in an older person might result in immune dysfunction and an increase in infectious diseases or other chronic immune related disorders.

Because of the recent accumulation of such new data, there are two new and major changes in how nutrient requirements in elderly people are being viewed. First, nutrient requirements for the elderly are no longer simple extrapolations from data derived on younger people. Rather, as has been stated, nutrient requirements are being defined on the basis of data derived directly from studies conducted on elderly people. Secondly, scientists are now interested in the amount of nutrient that it takes to prevent a chronic disease or chronic disease marker from appearing, rather than just the amount of a nutrient that it takes to prevent a deficiency state from occurring.

Looking upon nutrients as modulators of chronic disease risk represents an important paradigm shift. For example, how much of a nutrient does it take either to affect a marker of a chronic disease (such as homocysteine for atherosclerotic cardiovascular disease) or to help prevent the chronic disease itself, (for example, bone demineralization and osteoporosis)? Indeed, the newly evolving Recommended Dietary Intakes in the United States will define nutrient intake levels that should decrease an individual's risk of developing chronic diseases and degenerative conditions that are related to specific nutrients and associated with negative functional outcomes.⁵ Examples of strong links that have been made between specific nutrients and particular chronic illnesses are: the B vitamins (folate, vitamin B6 and vitamin B12) and the prevention of atherosclerotic cardiovascular disease and stroke;⁶ vitamin D and calcium and the amelioration of bone demineralization or osteoporosis;⁷ the antioxidant nutrients vitamins C and E and selenium and the prevention of atherosclerotic cardiovascular disease and/or certain site-specific cancers;^8,9 and the carotenoids, zeaxanthin and lutein, and the prevention of age-related macular degeneration.¹⁰

Since prevention of specific non-communicable diseases has been shown to be related to specific nutrients, the key element in planning diets for the elderly should be nutrient based dietary guidelines; that is, in order to reduce the burden of chronic disease by nutritional means, nutrient based guidelines in fact, become, essential to develop, Elderly people have distinctly different metabolic processes that do not allow for easy extrapolation of nutrient needs from results of experiments performed on younger adults. Because adults over 70 years consume less food than younger people (primarily because of decreases in energy expenditure) it is important to emphasize for old people:

à Foods that are nutrient dense in vitamins and minerals. For example, whole grain and enriched or possibly fortified breads and pastas are preferred to refined grain products for provision of adequate amounts of B vitamins. This is especially important since cereals and bread comprise the bulk of the diet of elderly people, many of whom are at risk for malnutrition.

à In the fruit and vegetable category, elderly should choose those that are deeply colored for provision of folate and antioxidant nutrients.

à Within the milk, yogurt, and cheese food group, emphasis should be placed on low-fat dairy products for the provision of adequate amounts of calcium and vitamin D.

à Within the nutrient rich meat, poultry, fish, dried beans, eggs and nuts food group, variety should be the key principle to follow with individual choices being made according to availability, affordability, chewability, individual preference and ease of preparation.

à Foods high in dietary fiber should be stressed and the fluid intakes of elderly people should be emphasized since thirst sensation is decreased in older people.

In order to reduce the burden of chronic non-communicable disease globally in our increasingly ageing world population, it is essential to develop and promulgate nutrient-based dietary guidelines. The best evidence to date is that specific nutrients or combinations of nutrients are related to specific chronic non-communicable diseases. In order to use this nutrition knowledge most effectively, geographically-specific dietary guidelines based on nutrient content and nutrient bioavailability are the best hope for maintaining elders in the healthiest state possible - and for as long as possible.

References

1.	Murray CJL, Lopez AD, eds (1996) Global Health Statistics In Global Burden of Disease and Injury Series Volume II, WHO and the World Bank, Harvard University Press.
2.	Boisvert BA, Castaneda C, Mendoza I, Langeloh G, Solomons NW, Gershoff SN, Russell RM (1993) Riboflavin requirement of healthy elderly humans and its relationship to macronutrient composition of the diet J Nutr 123:915-925.
3.	Ribaya-Mercado JD, Russell RM, Sahyoun N, Morrow FD, Gershoff SN (1991) Vitamin B6 requirements of elderly men and women. J Nutr 121:1062-1074.
4.	Meydani SN, Ribaya-Mercado JD, Russell RM, Sahyoun N, Morrow FD, Gershoff SN (1990) Effect of vitamin B6 on immune response of healthy elderly Annals NY Acad Sci 587:303-306.
5.	Food and Nutrition Board, Institute of Medicine (1994) How Should the Recommended Dietary Allowances Be Revised? Washington, DC. National Academy Press.
6.	Siri PW, Vewrhoef P, Kok FJ (1998) Vitamin B6, B12, and folate: association with plasma total homocysteine and risk of coronary atherosclerosis J Am Coll Nutr 17(5);435-441.
7.	Chapuy MC, Arlot ME, Duboeuf F, Brun J, Crouzet B, Arnaud S, Delmas PD, Meunier PJ (1992) Vitamin D3 and calcium to prevent hip fractures in elderly women. N Engl J Med 327:1637-1642.
8.	Stephens NG, Parsons A, Schofield PM, Kelly F, Cheeseman K, Mitchinson MJ, Brown MJ (1996) Randomised controlled trial of vitamin E in patients with coronary disease: Cambridge Heart Antioxidant Study (CHAOS) Lancet 347:781-786.
9.	Cancer Causes & Control. An International Journal of Studies of Cancer in Human Populations. (1996) Volume 7, No. 1, January.
10.	Seddon JM, Ajani UA, Sperduto RD, Hiller R, Blair N, Burton TC, Farber MD, Gragoudas ES, Halter J, Miller DT, Yannuzzi LA, Willett W (1994) Dietary carotenoids, vitamins A, C, and E, and advanced age-related macular degeneration. JAMA 272:1413-1420.
11.	Mclaughlin J, Holick MF. (1985) Ageing decreases the capacity of human skin to produce vitamin D3. Clin Invest 76:1536-1538.
12.	Klein PD, Graham DY, Gaillour A, Opekun AR, Smith EO (1991) Water source as risk factor for Helicobacter pylori infection in Peruvian children. Gastrointestinal physiology working group Lancer 337:1503-1506.

Dr Robert M Russell is Professor of Medicine and Nutrition, Associate Director, USDA Human Nutrition, Research Center on Aging, Tufts University, 711 Washington St. Boston Mass 02111 USA; email cquine@hnrc.tufts.edu