The Nutriture of People

AGNES FAY MORGAN AND LURA M. ODLAND.

GOOD, solid information about the actual nourishment of a sizable part of a population not merely the amounts and kinds of food one person or a family eats is of value to many.

Those who produce, process, and distribute food need data on the effects of diet on the health of people and the effects of their health and well-being, or lack of it, on their use of food.

Nutritionists and biochemists use the information to estimate recommended dietary allowances and the kinds and amounts of food that provide the necessary nutrients. Along with studies of animals and more laboratory observations of human beings, they also need large-scale investigations of groups of people in order to assess factors of individual variation, environment, habits, geography, origin, and knowledge of the importance of food.

Medical and dental doctors know how vital it is to penetrate the twilight zone between good and poor nutrition--the zone which lies between robust health and deficiency diseases like scurvy and rickets and in which may lie tooth decay and anemia. The observation of one or some persons may help them penetrate that zone, but a wider knowledge, such as that which comes from extensive surveys, is needed.

Homemakers would like to have some baseline for measuring what they have accomplished and where changes or improvements may benefit themselves and their families.

Government and military authorities get from surveys a better insight into social and economic trends and the comparative vigor and stamina of men who enter the armed services from the various sections of the country.

We have also an interest in the nutrition of people in other countries. A basic association which we all will do well to know more about exists between the health of a people and the development of a favorable economic, social, and political climate among them. Vast numbers of people still live amid severe stresses, one of which is malnutrition.

Guiding principles for studies on the nutrition of population groups were outlined in 1939 in a publication of the Health Organization of the League of Nations by Dr. E. J. Bigwood. At that time it was recognized that much basic information was needed to define more clearly the relationships between die-tart', clinical, and physiological observations in large-scale investigations of nutrition.

The National Academy of Sciences-National Research Council, through its Committee on the Diagnosis and Pathology of Nutritional Deficiencies, published in 1943 the first comprehensive summary of dietary surveys and nutritional appraisals that had been reported for population groups.

It summarized the available information on nutritional status on a uniform, authoritative, and comparable basis.

The information on the intake of nutrients of persons of all ages in many localities was compared with the recommendations. Many of the diets provided less than half of the recommended dietary allowances for several essential nutrients, but most of the diets provided more than 50 percent of the recommended levels.

Reliable data based on studies of blood serum were available in 1943 for only hemoglobin, protein, and ascorbic acid. All studies in this and other countries indicated a notably high prevalence of anemia, especially among children and pregnant women of the low-income groups. This was thought to indicate an inadequacy of iron in diets. Levels of vitamin C in the blood serum were low in a large proportion of the groups, especially among schoolchildren in all parts of the United States.

Together, the dietary, chemical, and physical-examination surveys in many regions showed that there were few indications of severe, acute deficiencies, but accumulated evidence pointed toward many mild or moderate states of deficiency.

The Council reported in 1943: "All evidence is in agreement that deficiency states are common among the Population of the United States. Most Of them are not the severe acute type. Rather they are less intense in degree and very much slower in their course. Predominately the deficiency states here are mild, moderate, or severe chronic forms. Because of their slow, gradual development, their presence is commonly unsuspected. In frequency and severity they increase with age and with lowered economic level. As yet optimum nutrition throughout the Nation has not been achieved; on the contrary, deficiency states are present on a large scale."

There has been further development of basic information since 1943 on which to base recommended dietary allowances for healthy people in the United States. Tables of food composition, which indicate the kinds and amounts of nutrients in food, have been expanded. Methods have been developed for determining the levels of essential nutrients in tiny amounts of blood, which can be taken easily from large numbers of people. There has been increased recognition of physical signs and symptoms that may be associated with low intakes of one or several nutrients.

A number of agencies have undertaken joint fieldwork and appraisals of the findings of surveys. Some of the surveys were organized by private research foundations. Others have been made by the Interdepartmental Committee on Nutrition for National Defense, representing nine departments of the United States Government that are concerned with health, agriculture, and defense; the State agricultural experiment stations individually and in regional cooperative efforts; medical and public health units, brought together under the Food and Agriculture Organization of the United Nations; and State and city departments of public health.

The procedures for determining nutritional status have been fairly well agreed upon, but the interpretation of the results is still somewhat variable. Statistical calculations usually must be used because of the bewildering variability of the observations. For that reason also the size of the sample must be large. The interpretation of even the most elaborate examination of the individual is beset by uncertainties, but group examinations may yield clearcut results.

Nutritional status--that is, the degree of well-being of a population as it is affected by food intake usually is appraised through coordinated studies of health statistics, particularly those on morbidity and mortality, the growth rates of children, birth rates, infant death rates, principal causes of death, and life expectancy;

data on food consumption that is, amounts of food that are available and that disappear and are presumably consumed;

detailed dietary records and histories;

clinical examinations, with special attention to changes in the skin, eyes, mouth, tongue, gums, muscles, blood pressure, and pulse rate;

biochemical tests of blood for various constituents associated with nourishment and tests of samples of urine, with or without preliminary administration of certain nutrients.

The population studied may include everyone in a city, county, State, or country, or it may be persons of a given age, sex, or physiological condition. The status of an individual can be assessed only by repeated and detailed clinical examinations, biochemical tests, and dietary records.

We divide this presentation into three main parts: Studies made by research workers in colleges, agricultural experiment stations, and independent organizations in the United States and other countries; reports of the cooperative studies on relationships of health, well-being, diet, and environment in the four regions of the United States, conducted by workers in agricultural experiment stations; and the findings of special studies and surveys.

MOST OF THE STUDIES of population groups until 1946 were concerned primarily with the relationships between the kinds and amounts of foods eaten and the general physical condition.

The composition of the blood may reflect nutriture, but taking samples of blood of large numbers of persons was not feasible before 1946 because of the amounts of sample necessary, the inconvenience to the person, and the time required for processing and analyzing the samples.

Microchemical methods of analyzing blood were developed by 1945 by O. A. Bessey, O. H. Lowry, and their associates in the Public Health Research Institute of the City of New York for eight of the dietary essentials or their important tissue derivatives.

The few drops of blood that were required could be obtained easily by puncturing the fingertip. The small--"micro-" samples could be analyzed efficiently and quickly. These analyses were particularly easy to use in nutritional studies of large groups.

The first extensive studies to use the microchemical methods of blood analysis were carried out in eight high schools in New York State during the fall of 1946. The New York State Joint Legislative Committee on Nutrition requested the survey in order to get data on the nutritional status of schoolchildren. The survey also gave research workers a chance to test the new microchemical methods.

Blood samples were collected from about 1,200 children, 11 to 19 years old, in schools of differing social and economic circumstances.

There seemed to be a fairly even distribution of vitamin A levels in blood serum. On that basis, the intakes of vitamin A were considered satisfactory for nearly all of the children. Serum carotene values, which indicate recent intake of green and yellow vegetables, varied somewhat more than serum vitamin A levels and revealed that some of the children in all the schools were not receiving recommended amounts of green and yellow vegetables.

Among 50 percent of the students in seven schools, low amounts of ascorbic acid (vitamin C) also indicated that fresh fruit and vegetables were not being eaten in recommended amounts.

The amounts of riboflavin in the blood samples varied, but no outstanding differences were found that could be taken to reflect high or low economic levels among the students.

Boys between 12 and 19 years old showed progressive increases in hemoglobin. The hemoglobin among girls remained practically the same as during childhood, although variations in hemoglobin were more pronounced among the girls. The amount of hemoglobin was related to the iron concentration of the serum and suggested the presence of an iron deficiency among girls that had low values of hemoglobin. Only a few boys and girls had hemoglobin values that could be classified as poor, but a significant percentage in most of the schools was classified as only fair.