Diets for the Aging
Born in Paris in 1920, JEAN MAYERreceived his MS. from the University of Paris when he was nineteen years old. After serving for fire years with the Free French forces, he came to Yale for his Ph.D. and is now a U.S. citizen. Dr. Mayer is associate professor of nutrition at the Harvard School of Public Health and a member of the FAO-WHO Joint Expert Committee on Nutrition.
THERE is little doubt that the prevalence of obesity in the United States is on the increase and that it is accompanied by increased mortality from a number of diseases, particularly diabetes and diseases of the heart, liver, and kidney. While this association of obesity and degenerative disease is properly, and depressingly, publicized, insufficient attention has been paid to the direct effect of obesity on functional disabilities. In the aged, obesity often makes moving about and self-care difficult or impossible in hemiplegia, in arthritis, and in fractures of the legs. And physicians are frequently reluctant to institute a weight-reduction program in a very old patient who has done well in spite of excessive weight.
While sympathizing with the desire not to upset a time-tested physiological and psychological balance, I must point out that a slow and progressive weight reduction is usually accompanied by improved ease of movement. A decrease in weight of not more than twenty pounds may be sufficient to increase considerably the rate and extent of ambulation, and thus the enjoyment of life. Even in the absence of any visible improvement in muscular strength, a weight reduction also decreases the probability of further locomotor disabilities consequent to arthritis, cardiovascular disorders, or accident. Weight reduction in the aged is admittedly difficult. Where activity must be limited, decrease in food intake may be the only way to create a deficit in the energy balance.
If weight reduction is necessary in an aged patient. the diet may not only have to be severely restricted, but it may also have to be changed qualitatively so that the intake in protein, vitamins, and minerals can continue to be or begin to be adequate. Understandable resistance to changes in patterns of nutrition which have been in existence for several decades, mastication difficulties, and cost factors all make difficult the devising of a successful reducing diet.
Finally, the always undesirable practice of repeated crash weight reduction followed by weight gain may work an even greater stress on the elderly than it does on younger people. Follow-through with reduction programs on the part of the aged patient and follow-up by the physician are even more necessary than in other individuals.
It is both difficult and dangerous to generalize on just what foods — and how much of each of them — older people should have for optimum health and efficiency. Nevertheless, the best proof of the demand for some general guidance is the enormous volume ol advertising, often of doubtful veracity, specifically directed toward our senior citizen. Available facts do not support the idea that older people have specific nutritional needs. Any generalization about how much the aged should eat must be cautious.
Back in 1949 the first committee on calorie requirements convened by the Food and Agriculture Organization of the United Nations (of which I was a member) recommended that after the age of twenty-five, the caloric allowance suitable for a human being should be decreased by 7.5 percent in each successive decade. For example, if at twenty-five the individual is in good health, good weight, and in good fat-to-weight ratio (judgments to be professionally determined) and is consuming around 3000 calories a day, he should start to cut that amount down so that it is 225 calories less by the time he is thirty-five; by the time he becomes forty-five, calorie consumption should be decreased by another 225 calories per day; and so on in each succeeding decade.
During the eight years that followed the committee’s original pronouncement, however, there was an impressive accumulation of facts which refuted the assumption that energy expenditures decreased steadily during the earlier stages of aging. The new data showed that the decrease was not as great as we had believed. In other words, people in the age groups concerned were, in the main, spryer and busier than had been thought, and therefore they should not be put too sternly on such short rations.
When the second committee met in 1957, we were convinced that, provided the adult remained normally active or continued to work at an occupation which demanded physical labor, the decrease in food requirement we had recommended previously was too great during the middle years. In the intervening period, it had been unofficially determined that only after forty-five, at the earliest, did energy requirements decrease significantly. Accordingly, the committee proposed that the caloric allowance be cut by only 3 percent of the requirement at twenty-five for each of the next two decades. For the decades from forty-five to fifty-five and fifty-five to sixty-five, a cut in food intake of 7 percent was suggested, and for the decade from sixty-five to seventy-five, a further decrease of 10 percent. These successive percentages are not applied to each new base but are applied to the requirements obtaining at twentyfive, and it will be reassuring to the vigorous and food-fond reader of seventy-five that the committee urged no further tampering with the amount of food it was willing to apportion him.
But the 1957 dicta are far from the final words on this vital subject. Still more recent information argues for both a more progressive and a more individual basis for the caloric allowances of those who are no longer young. Dr. J. V. G. A. Durnin believes it useful to try to classify with more precision differing degrees of aging. He calls people between sixty and seventy-five “elderly” and calls people seventy-five and over “old.”His main concern is with the elderly. His own studies, as well as those of other contemporary authorities, show that in such Western countries as Great Britain and the United States, physical activity changes little between the ages of thirty and sixty to seventy. During this same long stretch, however, muscular efficiency appears to decrease with age, in part because of the slow loss of precision in muscular coordination. This decrease in strength and proficiency leads an older person to require more energy for a particular task than a younger person. In other words, if the older person continues to do what he did when he was younger, he will need to be nourished sufficiently to provide him with the extra energy required.
Finally, while there are progressive changes of an unhelpful nature in body composition with each year after the body reaches maturity, such as a progressive replacement of protein by fat, these are not (except in really old or excessively sedentary people) quite as marked as is commonly believed. Replacement of muscle tissue by fat proceeds relatively slowly in individuals who remain physically active.
The slowness in the decrease in physical activity, in the changes in body composition, and in the reduction in efficiency of muscular movement thus accounts for the slight change in the total metabolism of large groups of men. This is particularly true for men whose work entails physical exertion which varies little over decades. For them, decreasing the amount of food usually becomes appropriate only when abrupt retirement brings to a stop customary physical activity. The cut in food intake, rarely in our culture an attractive program, often can be made less burdensome if a pattern of sufficiently demanding and interesting activities is substituted for the familiar ones.
The limitation on food intake is, in general, more applicable to aging women, particularly housewives. For them the physical tasks of housework usually show a marked drop in later fife. And for them, too, some kind of regular exercise will permit them to have more of their customary cake by providing an outlet for its calories. We may conclude that if the caloric intake of the aged, particularly men, was not excessive in their early middle age, and if they have retained the same schedule of work and other activities, there is no reason to add the burden of eating less to the difficulties which getting old can bring.
If activity drastically diminishes because of chronic disease, change in occupation, or confinement, then, obviously, caloric intake must be decreased to prevent obesity, itself a pathological condition and, too commonly, also chronic. This, however, is true at any age. And what is good for people in general is in most instances good for old people, too.
BECAUSE of the very fact that so few of the obese live to an old age, it is not surprising that undernutrition, and resultant emaciation, is more frequently seen in old age, particularly extreme old age. In fact, there appears to be general agreement that admissions to general hospitals with partial or serious malnutrition are more numerous in old patients than in young and middle-aged ones. But despite the voluminous propaganda that declares it, vitamin deficiencies are not common in the aged. They are usually found in oldsters who are subsisting on monotonous and nondiversihed meals. In many cases normal foods have been replaced by diet fads, perhaps supplemented by expensive miracle preparations or by too much alcohol.
There are physiological, psychological, and sociological factors involved in this kind of malnutrition. A combination of factors is often seen in the same person. Structural disease of the esophagus or stomach may cause discomfort and result in the patient’s never eating adequate meals. Lack of teeth may make proper mastication difficult and may be a very serious problem in the aged. Disinterest in eating because of loneliness is not infrequently observed, particularly in patients who live alone and are unable or unwilling to go through even cursory meal preparation. Economics is paramount in many cases. It has been estimated that in the United States at present, 75 percent of the people over sixty-five have a cash income ofless than $1000 per year, and 15 percent of those most in need of dietary improvement, less than $500 per year.
Finally, an important factor in the determination of the diet of many older patients is food faddism. Their often incurable complaints cannot be eliminated by medical treatment; in their search for relief they grasp at the irresponsible promises of wonder healers. The treatment of arthritis, for example, is infested by these quacks, and a great deal of the propaganda for youth elixirs, nature foods, and fad diets is directed toward the aged. Such expenditures may work great hardship on limited budgets and may be made at the cost of variety in the diet and proper medical care.
Hospitalization, with particular attention to diet, often results in gains of tip to 15 percent of body weight or more in chronically emaciated persons. A number of ill-defined deficiency symptoms also disappear. Such treatment is by no means always successful; irreversible physiological and psychiatric conditions and often insurmountable social problems continue to operate to restrict the intake of the patient. Nevertheless, there is little doubt that lack of appetite is common in the aged. By weakening the patient and making him feel sick, his malnutrition may be self-perpetuating and even self-accelerating. Undernutrition not only decreases the enjoyment of life but may make the older patient more difficult to care for and less likely to resist infections or surgical traumas.
The possible relationship to heart disease of fat content and kind of fat is of obvious relevance to the problem of nutrition in the aging. This subject has received a great deal of popular attention recently and need not be reviewed here. There is general agreement that, by and large, saturated fatty acids, found in milk, butter, most margarines and shortenings, meats, and eggs, tend to elevate serum cholesterol, usually regarded as the villain in coronary heart disease. Incidentally, it may be useful to point out that a number of other factors, ranging from dietary cholesterol to types of carbohydrates, fiber content, trace elements, and various vitamins, have also been found in certain experimental studies to have some effect on serum cholesterol. The applicability of these findings to the prevention or treatment of heart disease is, however, still open to question.
Recent studies emphasize also the possible influence of exercise in preventing heart disease, and the unfavorable effect of cigarette smoking. From a practical viewpoint, it appears reasonable to suggest that aging individuals and probably all adults, male in particular, should consume a diet not too high in fats and should adopt methods of food preparation which will minimize the total saturated-fat content of the diet.
The advisability of a drastic decrease in salt intake in the treatment of many cardiovascular diseases — the salt-free diet — is well documented, and its practice is familiar to many readers. Available experimental data on rats and data on men are, however, at best suggestive that limitations of salt intake are useful in the prevention, rather than the treatment, of hypertension and coronary accidents.
R. C. Garry, professor of physiology at the Glasgow Medical School and an excellent gerontologist, has said, “Above all, we must see the elderly in continuity with youth and middle age. We accept that the child is father of the man. We could equally well say the elderly person is the child of his youth and years of maturity. The elderly do not form a special isolated section of the community: we must continually hark back to the earlier years.”
Nowhere is this more true than in the field of nutrition and in that of personal hygiene. Consumption of a varied diet, adapted in amount to the need of the moment, avoidance of dietary excesses, avoidance of an excessively fat diet, moderate salt intake, generous fluid intake, sufficient exercise and rest — these recommendations are as valid for old age as they are for young adults and the middle-aged.