Nutritional Approaches To Aging Research

Gairdner B. Moment, Richard C. Adleman, George S. Roth, Moment

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9781315896021
• eBook ISBN: 9781351092029
• Edition: 1
• Topic: Medicine
• Subtopic: Biology

The general plan of this volume, Nutritional Approaches to Aging Research is for each chapter to present first a reasonably succinct state-of-the-art appraisal of present knowledge in the particular field or problem covered. This will vary considerable depending on the subject matter. Following this, each chapter will focus on the problems and pitfalls, both conceptual and technological, of work in the particular field and, no less important, present some of the opportunities and implications of work in that particular area.

Chapter 1

INTRODUCTION

G.B. Moment

TABLE OF CONTENTS

I.	Objectives of Gerontological Rescarch
II.	The Newly Discovered Importance of Nutritional Research
III.	Present Theories of Aging
IV.	Some Roadblocks to Nutritional Research
V.	Some Neglected but Important Problems
References

I. OBJECTIVES OF GERONTOLOGICAL RESEARCH

The stated aim of the National Institute on Aging is to gain the knowledge necessary to alleviate “the physical infirmities resulting from advanced age (and) the economic, social and psychological factors associated with aging which operate to exclude millions of older Americans from a full life and place in our society.” The importance of this in the U.S. where the proportion of older individuals continues to grow at the expense of younger must be clear to all. The cost of Social Security for those who have retired either by choice or from necessity is staggering, even excluding nursing home care. To make it possible for people everywhere to age well, both physically and mentally so that a satisfying old age can be the good fortune of us all is not only a humane goal but a realistic one.

What is not a realistic goal is the discovery of the Fountain of Ponce de Leon, the fountain of eternal youth, or perhaps of eternal middle age. However astronomically removed such a possibility, it cannot be excluded absolutely. Helmholtz, as a brash young man, measured the speed of a nervous impulse after the leading physiologists of Europe had declared that it would be forever impossible. Moreover, the truly shattering surprises in the history of knowledge have not been either foreseen or searched for. Roentgen did not intend to discover X-rays. He was as surprised as everyone else. Columbus did not set sail to discover a new world but to reach India by a shorter route.

It is conceivable that an aging chronometer process of some kind exists in every cell of the body or in the hypothalamus, the limbic, or some other region of the brain, and that this biochronometer could be slowed or even stopped. The discoverer might be investigating the cause of jet lag, or the timing mechanism of circadian rhythms which exist throughout most if not perhaps the entire living world. It might be, of course, that the biochemical machinery of the aging timepiece does not lie in the nervous system. Plants possess a circadian “clock” and no nervous system.

Three salient facts demand attention. The probability of stopping the hypothetical aging clock appears all but infinitely removed, while the benefits from age-related research are real. Secondly, if an aging process of whatever sort could be stopped, it would result in a watershed in human history fully comparable to the discovery of the use of fire or how to domesticate plants and animals. Unimagined population problems would arise at once, along with vast psychological, personal, and social problems. Strehler²⁴ has discussed these issues in the fields of physical health and survivorship curves from ancient times to the present, of mental health, of social effects, and of economic effects and polycareers. Lastly, for better or for worse, the only way to be sure of escaping such a discovery would be to halt most medical and physiological research, even on the plants. Serendipity in science is rare but very real.

We are left with the conclusion that gerontological research will provide a continuing flow of beneficial discoveries and that the hazard of a mega-breakthrough to permanent control of aging is as remote as the possibility of the existence of a single well somewhere that yields molasses. Only someone considerably more competent in Neo-Bayesian statistics than Lewis Carroll’s Alice or the present writer could say how remote that is.

II. THE NEWLY DISCOVERED IMPORTANCE OF NUTRITIONAL RESEARCH

One of the most remarkable and probably one of the most important facts so far discovered in the field of gerontology is that the maximum life span of certain warmblooded (endothermic or homoiothermic) animals can be extended by 50% or more by dietary restriction. This dramatic result has so far been tested only in rats and mice, but there is a high probability amounting almost to certainity that it could be replicated in all mammals including humans, a point to which we will return later.

This surprising result of what is often called “underfeeding” was recorded first by Osborne et al.¹⁸ in 1917. It was further investigated by McCay⁸ and associates in the 1930s, and Berg and Simms² in the 1960s; but even after Ross,²⁰ Barrows (this volume) and Goodrick’ began their contemporary work on this apparently paradoxical phenomenon, very few additional investigators have entered the field.

Nevertheless, the possible implications of dietary restriction studies are enormous on both the theoretical and practical sides. On the theoretical side it is quite possible that food restriction studies will prove to be a very useful probe to assist in understanding the biochronometer of animal development, whatever it may turn out to be, from sometime prior to reproductive maturity through the final stages of senescence. The mechanism or mechanisms by which food restriction extends lifespan are unknown. However, they appear to act at a very deep level because the 50% or more extension of life span is far greater than can be explained by the elimination or postponement of the diseases characteristic of the aging rodent, although dietary restriction does that.

There is some evidence cited by Everitt (this volume) and by others that dietary restriction results in a form of hypophysectomy which is the underlying cause of aging extension. Wurtman et al.²⁹ and Lytle and Altar¹² among others have shown that diet can influence brain catechol amines involved in the neuroendocrine system and even influence the choice of food. In this series, Ross²⁰ and associates have shown that self-selection of foods by rats influences the age of onset of renal, pulmonary, and other diseases of aging as well as the time of incidence of tumors. Restriction of food lowers basal metabolism somewhat so it is conceivable that specific metabolic rate is reduced more than the specific activity of superoxide dismutase and other enzymes protective against the destructive effect of oxidation. But whether the rate of aging is determined by some form of Orgelian wear and tear from radiation, thermal agitation or chemical accidents on the genetic material, or by some as yet unguessed process, dietary restriction will remain one of the probes in helping to distinguish between the multiplicity of aging theories.

On the practical side, the data now available present new research opportunities in the field of nutrition which promise new vistas for a future in which human life will be healthier and more productive and satisfying over the full 3 score and 10 years and probably a bit more.

Entirely aside from whether or not food restriction extends life span beyond the natural limit characteristic of the species, a reevaluation of the traditional nutritional guidelines is in order. The fact alone that the age of onset of specific diseases and of specific types of tumors of several organs is very significantly postponed justifies an investigative program not presently in sight.

A first order of business is to confirm and perhaps extend the studies of dietary restriction on mammals other than rats and mice. That food restriction would increase the health and longevity in all mammals seems extremely probable on general physiological principles, but there is at least one specific study on the human which supports such an extrapolation from the rat and mouse.

Ross,²⁰ Barrows, and Goodrick⁹ have each found that alternate feeding and fasting results in marked life extension in these laboratory rodents. Ross cites a study where E. A. Vallejo divided some institutionalized subjects (number unspecified) all over 65 years of age into two groups. One group was given the regular institutional food every day. The other was given the same food one day and on alternate days only milk and raw fruit. The caloric intake on the “lactopomaceous” days was 60% less and the protein intake 28% lower than on the standard diet days. During the 3 years of this study, the length of time spent in the infirmary by those fully fed was twice that of those fed every other day. Twice as many of those fed the standard diet every day died.

This is a single study and the details apparently are not available. Clearly, additional studies should be made and it should not be difficult to find volunteers if they are given the proper motivation.

Life span extension by dietary restriction has been known for many years in a number of invertebrates, insects, a crustacean (Daphina) and in rotifers. Neither this, nor the case cited by Ross, is enough to justify neglecting taking a hard look at the results of dietary restriction in some mammal other than the mouse and rat. The guinea pig comes to mind as a relatively short-lived animal having a life span of about 7 years. Although a rodent, it requires an outside source of vitamin C like the human but unlike rats and mice. Dogs would be especially interesting first because they are not rodents but also because of the puzzling way large dogs have a shorter life span than small ones.

The present data about the results of restriction indicate that a number of standard ideas about nutrition, at least human nutrition, will need to be reexamined. The long-held belief, for example, that the best of all possible diets is simply a well-balanced one may turn out to be only part of the story. Quantitative considerations may take on a new dimension. As far as protein is concerned, more may actually be worse for the best health and longest active life. It has been known for over 80 years through the pioneering work described by Matthews¹³ of Chittenden and his associates that a man can satisfactorily carry out “ordinary exertions” on less than an ounce of protein per day. Because in restriction studies it is uncertain whether reduction of calories or of protein or both is most effective in postponing diseases and increasing healthy life span, the whole question of the role and the amount of protein in the diet stands to be reexamined.

Before any restriction diet can be safely used for people, there is a host of questions which spring to mind and require answers. An important caveat to keep always in mind is that severe quantitative and qualitative protein deficiencies result in mental retardation and in kwashiorkor in children. That the mental retardation, as shown by the work of Brasel,³ Winick and others, can be at least partially reversed and kwashiorkor cured does not remove that caveat. Moreover, on some restriction diets the rats have been stunted in growth, undeveloped sexually, and, in some, scrawny. How are these undesirable effects to be avoided? The differences between restriction of calories and of amino acids remains to be clarified. When should the restriction begin? Soon after weaning, sometime before reproductive maturity, well after that event? Is alternate fasting and feeding more effective biologically and psychologically than level restriction? What role does exercise play? How can vitamin and trace element requirements be met? What is the role and significance of self-selection of diet? The number of variations, combinations, and permutations of these different approaches to the problem is certainly very large, even only counting those which appear especially significant.

After there are reasonably firm answers to questions of this sort, tests should begin on some of the smaller, i.e., shorter lived, primates and on human volunteers. Obviously this is an investigative program which can be undertaken only by workers in a large university or research institute able to make a firm commitment extending over several decades.

Meanwhile it appears highly important to begin at once a study of several quite different groups of people living on a low subsistence level along with a parallel study of control groups on what is considered an ample diet. How does the average life span of two sets of such groups compare? Do they die of the same diseases? How does their general level of physical and mental energy compare? Such a study could provide data unattainable in any other way.

In conclusion, there would appear to be no area with any greater potential than the study of restriction dietary programs for achieving the goal of gerontological resear...

Table of contents

• Cover
• Title Page
• Copyright Page
• Table of Contents
• Chapter 1 Introduction
• Chapter 2 Nutrition and Age-Related Changes of Carbohydrate Metabolism
• Chapter 3 Lipids In Nutrition and Aging
• Chapter 4 Human Aging: Protein and Amino Acid Metabolism and Implications for Protein and Amino Acid Requirements
• Chapter 5 The Vitamin Status and Requirements of the Elderly
• Chapter 6 Trace Elements in Aging Research: Emphasis on Zinc, Copper, Chromium, and Selenium
• Chapter 7 Dietary Antioxidants and Aging on Membrane Functions
• Chapter 8 Effects of Aging Upon Intestinal Absorption
• Chapter 9 Nutrition in the Development and Aging of the Skeleton
• Chapter 10 Aging, Arthritis and Food Hypersensitivities and Allergies: A Research Opportunity Revisited
• Chapter 11 The Important Interaction of Alcoholism with Nutrition in the Elderly
• Chapter 12 Dietary Restriction and Life Extension — Biological Mechanisms
• Chapter 13 Nutrition and the Hypothalamic-Pituitary Influence on Aging
• Index