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Celebrating 25 years of nutrition research and education.
 

Good Nutrition is Ageless

Good Nutrition

The fastest growing segment of the population in most industrialized countries is the elderly; and too often this is also a group most susceptible to many health risks from a nutrient poor diet. Evidence from numerous sources indicate that a significant number of elderly fail to get the amounts and types of food necessary to meet essential energy and nutrient needs. There are a wide range of reasons why older individuals might not be eating the most nutritious diet which is all the more reason why health professionals and care providers need to be constantly aware of the necessity for maintaining an optimal nutritional health status in the elderly. Physiological, psychological and economical changes in the later years can all contribute to poor nutrition among the elderly, and accordingly establishment of healthy nutritional habits often requires a multifaceted intervention approach to address the wide range of factors contributing to suboptimal nutrient intakes.

After age fifty there are many metabolic and physiological changes which impact on the nutritional needs of an individual. The metabolic rate slows and can decline as much as thirty percent over a lifetime. This results in decreased caloric needs which can be complicated by changes in an older person's ability to balance food intake and energy needs. Even with a decreased caloric need, many older people have difficulty getting sufficient calories which can eventually lead to chronic fatigue, depression, and a weakened immune system. As we age our body composition changes with a decrease in lean tissue mass (as much as 25%) and an increase in body fat. Such changes can be accelerated because older adults utilize dietary protein less efficiently and may actually need a greater than recommended amount of high quality protein in their diet to maintain lean tissue mass. These changes in metabolism and physiology can be exaggerated due to complications from digestive difficulties, oral and dental problems, and medication-related eating and nutrient problems.

And while there are many physical and clinical factors that can contribute to undernutrition in the elderly, there are as many equally important social and economic factors which can further complicate the nutritional well-being of an older individual. Contributing factors include loneliness, lack of cooking skills, depression, economic concerns, weakness and fatigue, and, in too many cases, an unwarranted fear of many high quality, nutrient dense, affordable foods. All these factors can contribute to the fact that a significant number of older men and women consume less food than required to meet energy and nutrient requirements, and are at moderate to high nutritional risk.

The nutritional risk of the elderly is no doubt affected by the fact that the low-fat, low-cholesterol diet message has been heard loud and clear by this population. Many elderly readily accept the fear of fat and cholesterol message because of their heightened concern regarding their own health, and the knowledge that the risk for chronic diseases increases with age. And while dietary limits on fat and cholesterol consumption are widely assumed to be effective risk-reduction interventions in young and middle-aged adults, the appropriateness of such dietary restrictions in older individuals has become an area of considerable debate.

There is evidence that good nutrition promotes vitality and independence whereas poor nutrition can prolong recovery from illness, increase the costs and incidence of institutionalization, and lead to a poorer quality of life. Good nutrition is ageless and the message to older people must be that the quality of your nutrition is basic to the quality of your life. And while the evidence of the value of nutritional balance is clear, the nutritional status of many older individuals lacks that balance and the problem is often complicated by a fear of foods and over-emphasis on single nutrient issues. In this review we will look at the relative benefits of cardiovascular risk reduction with dietary restrictions versus the potential risks to the nutritional well-being of the elderly when these interventions often result in reductions in many nutrient dense foods. The real question which must be addressed is whether the "one diet fits all" approach readily fits both the nutritional needs and health concerns of the elderly.

Dietary restrictions of fat and cholesterol are implemented in order to lower plasma cholesterol levels and the associated cardiovascular disease risk. The bases for this dietary intervention approach to risk reduction are studies in middle aged populations which indicated that an elevated plasma cholesterol level is an independent risk factor for heart disease and that reduction of an elevated cholesterol reduced relative risk. To date, however, there have been no long-term drug or dietary plasma cholesterol lowering intervention trials in healthy patients older than 65 years. Some investigators have presented data indicating that while total cholesterol levels are an excellent predictor of CHD risk in middle-age, they are a poor indicator of events in elderly patients [Corti et al. 1995]. Krumholz et al. (1994) followed 997 subjects 65 years and older for 4 years and was unable to document a graded and continuous association between plasma cholesterol levels and CHD mortality or all-cause mortality in persons older than 70 years. Studies by Kronmal et al. (1993), using data from the Framingham Heart Study, indicated that HDL cholesterol levels are a better predictor of risk in the elderly than LDL cholesterol. Analysis of the data to determine the relationship between the various causes of mortality in the different age groups and specific plasma lipoprotein cholesterol levels indicated that for CHD mortality the positive association with LDL cholesterol decreased with age. HDL cholesterol was a strong negative predictor of CHD mortality until past 80 years of age. For total mortality the relationship with LDL cholesterol showed a significant age-interaction with relative risk of death crossing from positive to negative at 62 years of age. In contrast, HDL cholesterol levels were positively associated with better survival at all ages. Similar results have been reported by Corti et al. (1995) showing that the relative risk of death from CHD in persons 71 years and older is 2.5 times higher with an HDL less than 35 mg/dl compared to those with levels greater than 60 mg/dl. The authors estimated that for each unit increase in the total:HDL cholesterol ratio there was a 17% increase in the risk of CHD death.

One of the unfortunate consequences of the lower-fat diet message is that often the replacement for fat calories are calories from simple carbohydrates which can elevate plasma triglyceride levels resulting in lower HDL cholesterol concentrations which has been shown to be an important determinant of CHD risk in the elderly. An additional effect of a low-fat, high simple carbohydrate diet is to increase the expression of small, dense LDL particles (Krauss and Dreon 1995) which are relatively more atherogenic than larger, more buoyant particles (Gardner et al. 1996). There are also concerns that low-fat diets may in some individuals exacerbate insulin resistance leading to hyperinsulinemia which is an independent risk factor for CHD (Despres et al. 1996). It should also be noted that calorie dense foods too often are the easiest replacement for the higher fat, nutrient dense foods. With a diminished sense of caloric balance the intake of high carbohydrate foods can readily lead to obesity and its associated risk of CHD (Rimm et al. 1995). Intake of calorie dense, nutrient poor foods can also lead to decreased intakes of many important nutrients thought to play important roles in decreasing CHD risk. These include the fat and water soluble antioxidants to minimize production of oxidized LDL (Hodis et al. 1995, Kushi et al. 1996), vitamins B12 and folate to reduce the risks associated with elevated levels of plasma homocysteine (Boushey et al. 1995, Herzlich et al. 1996), and other vitamins and minerals thought to play roles in the regulation of plasma lipoproteins and blood pressure.

In too many cases it is simply easy for the elderly individual to reduce consumption of the many valuable nutrients found in abundance in the food groups they have been advised to restrict or in some cases actually eliminate. Repatterning dietary choices in an elderly individual can result in elimination of major food groups from the diet without any real nutritional benefit, and with some nutritional risk. It is for reason such as this that it is essential that the impact of dietary modifications for fat intake on the overall quality of the diets of elders be carefully evaluated. It has been recommended that dietary modifications for older adults not be overly restrictive and that the major emphasis should be on dietary needs to address immediate problems such as diabetes, food allergies and renal problems. Nutrition advise for older adults should be designed to respond to the changing physiological, psychological, social and economic capabilities of the individual while assuring that the overall nutritional needs are meet with the freedom to keep meals and eating an important aspect to the quality of life during the later years.


REFERENCES

Boushey, C.J., Beresford, S.A.A., Omenn, G.S. et al. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease: probable benefits of increasing folic acid intakes. JAMA 1995;274:1049-1057.

Corti, M-C, Guralnik, J.M., Bilato, C. Coronary heart disease risk factors in older persons. Aging Clin Exp Res 1996; 8:75-89.

Depres, J-P., Lamarche, B., Mauriege, P. et al. Hyperinsulinemia as an independent risk factor for ischemic heart disease. N Eng J Med 1996;334:952-957.

Gardner, C.D., Fortman, S.P., Krauss, R.M. Association of small low-density lipoprotein particles with the incidence of coronary artery disease in men and women. JAMA 1996;276:875-881.

Hodis, H.N., Mack, W.J., LaBree, L. et al. Serial coronary angiographic evidence that antioxidant vitamin intake reduces progression of coronary artery atherosclerosis. JAMA 1995;273:1849-1854.

Krauss, R. M., Dreon, D. M. Low-density-lipoprotein subclasses and response to a low-fat diet in healthy men. Am J Clin Nutr 1995;62:478S-487S.

Kronmal, R.A., Cain, K.C., Ye, Z., Omenn, G.S. Total serum cholesterol levels and mortality risk as a function of age. A report based on the Framingham data. Arch Intern Med 1993; 153:1065-1073.

Krumholz, H.M., Seeman, T.E., Merrill, S.S. et al. Lack of association between cholesterol and coronary heart disease mortality and morbidity and all-cause mortality in persons older than 70 years. JAMA 1994;272:1335-1340.

Kushi, L.H., Folsom, A.R., Prineas, R.J. et al. Dietary antioxidant vitamins and death from coronary heart disease in postmenopausal women. N Eng J Med 1996;334:1156-1162.

Rimm, E.B., Stampfer, M.J., Giovannucci, E. et al. Body size and fat distribution as predictors of coronary heart disease among middle-aged and older US men. Am J Epidemiol 1995;141:1117-1127.

 

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