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C. EDITH WEIR Overview of the Role of Animal Products in Human Nutrition This overview of the role of animal products in human nutrition begins with a look at the limitations of the available data. First, we need to know what quantities of animal products are being consumed. Reliable, precise data on the present consumption of meat and animal products that can be used to express the nutritional contribution of these foods in U.S. diets are not readily available. MAJOR SOURCES OF DATA Several sources of data provide information on the amount of meat and animal products in the U.S. dietary. The five major sources are: na- tional per capita estimates, surveys of foods used by households, sur- veys of foods ingested by individuals, the Ten-State Nutrition Survey, and the Health and Nutrition Examination Survey. The national per capita estimates of the number of pounds of the various food commodities available for use by the civilian population are developed annually by commodity specialists of the USDA (Clark, 19751. These estimates, often referred to as "disappearance data," are obtained by adding the total quantities of food produced in the country each year, the quantities of food carried over from the previous year, and all imported food. Deducted from these totals are the quantities that are exported, left over at the end of the year, taken by the armed forces, and used for feed, seed, or nonfood purposes. Estimated losses occurring in distribution channels are deducted. The remaining food is considered s

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E DI TH WEIR to have "disappeared" into civilian channels and to approximate annual civilian consumption. Per capita consumption is obtained by dividing total civilian consumption by the number of people eating out of civilian food supplies (based on current census data). The nutritive value of the per capita food supply is obtained by multiplying the quantities of foods consumed (about 250 items measured on a retail weight basis) by appropriate food composition values. Most of the values are taken from Table 2 of USDA Agriculture Handbook No. 8, Tables of Food Composition. Estimates of the nutritive value of the food supply cover only food commodities. Annual consumption and nutrient estimates are available starting with 1909 (USDA, 19701. Cur- rent estimates are published annually in the November issue of National Food Situation, published by the USDA's Economic Research Service. Estimates of food consumption and of the nutritive value of the food supply are used chiefly to study trends (Friend, 1967; Clark, 1975~. They show the marked changes that have occurred in our food con- sumption and the nutrient content of the average diet over the years. Table 1, showing a dramatic change in sources of protein, is an example of how the data can be used. Although the estimates show the quantities of specific nutrients avail- able for consumption in the country as a whole, they do not take into account losses and waste after food leaves the retail outlet or variations in the distribution of food among different population groups. Neither do they deduct for food fed to pets. Hence, these nutrient levels provide only an indirect measure of the food actually consumed by people and of the nutritional adequacy of the national food supply. The estimates of nutrients in the food supply, published each No TABLE 1 Protein Available per Capita per Day and Sources (Se- lected Years, United States ~ a Total Protein Animal Vegetable Year (g) (%) (%) 1901-1913 102 52 48 1925-1929 95 55 45 1935-1939 90 56 44 1947-1949 95 64 36 1957-1959 95 67 33 1965 96 68 32 1972 101 70 30 a SOURCE: Clark ( 1975) ~

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Role of Animal Products in Human Nutrition 7 vember in National Food Situation, do have an advantage over national survey data (USDA, 1967) in that they are developed annually rather than every 10 years. They also are easier to use when one wishes to obtain estimates of certain proportions for example, proportions of animal and vegetable protein. Surveys of foods used by households are made periodically by the U.S. Department of Agriculture (USDA, 1967; Clark, 19751. The first nationwide survey based on statistical sampling of households was made in 1936-1937. Since then, four large-scale studies have been made- in 1942, 1948, 1955, and 1965-1966. The latest nationwide study in- cluded about 15,000 households and obtained information that could be used to classify families by income, size of household, and geo- graphic region. The "list recall" method was used to obtain data on food bought, produced, or obtained from other sources and used up during a 7-day period. No deduction was made for loss or waste of edible food. Food fed to pets was presumably excluded. Many persons think that estimates made by this method are too high. These studies provide food-consumption data only on household averages, not on individuals. They are useful in evaluating regional and economic differ- ences, dietary adequacy, and shifts or trends in intake of food groups. Table 2, based on the 1965-1966 food consumption survey, estimates the percentage of different meat products used per person in four geo- graphic regions. Beef intake was higher in the western states (41% of all meat eaten) than in the southern states (32% ), and more pork was used in the north central states (25%) and southern states (26%~. Surveys of food used by households should be made at least every 10 years. Food prices, food habits, life-styles, and food supplies have changed markedly since the last survey in 1965-1966. Even so, these are the best data on household food consumption that we have. TABLE 2 Percentage of Different Meat Products Used per Capita in Four Regions a North Northeastern Central Western Southern States States States States Beef 35 39 41 32 Pork 21 25 21 26 Poultry 19 17 18 20 Lunch meat 10 11 9 9 Fish, shellfish 8 6 7 10 Other meat 7 2 4 3 ~ SOURCE: USDA (1967) .

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8 C. EDITH WEIR In 1965-1966 the USDA (1969) also made a survey of foods ingested by individuals. It differed from the household study in that the food was measured at the menu level the so-called food intake of individuals- in which there is presumably no loss. About 14,500 persons were in- cluded. Data from this survey are likely to underestimate results be- cause of the difficulty in getting respondents to report on all the day's food in an unstructured schedule. When the results of the nutrient in- take of individuals (suitably weighted together) are compared with the household data, a considerable gap exists. The household data are larger by a margin that is even greater than might be expected to result from considerable waste of food. The Ten-State Nutrition Survey, 1968-1970, was made by the De- partment of Health, Education, and Welfare (USDHEW, 1972a,b). The survey included selected populations from 10 states and New York City. It was the largest survey of nutritional status ever made in the United States; 40,000 persons had some type of examination to evaluate their nutritional status. Primary emphasis was on lower-income groups. Dietary data were provided for 11,000 persons. Only a limited amount of statistics on foods consumed is given in the reports. These are pri- marily on the frequency with which food groups are consumed. Tables on the percentage contribution of food groups to the total nutrient con- tent are shown for all sex-age groups in the survey. Two types of 24-h food-recall information were obtained. One was on household use of food without regard to distribution among household members. The other was on selected individuals from the groups most likely to be at nutritional risk: persons 60 years of age or older, pregnant and lactating females, boys and girls 10-16 years of age, and children under 3 years. The main purpose in obtaining this dietary information was to relate to the biochemical and clinical data. Although the food-intake data are not representative of the national picture, further analysis could be useful in defining the role that selected or fabricated animal products might have in improving the nutritional status of this population group within existing economic constraints. The Health and Nutrition Examination Survey, which is now part of the National Health Survey authorized by Congress in 1956, is an ongoing program of the Department of Health, Education, and Welfare. Its purpose is to measure and monitor the nutritional status of the U.S. population (USDHEW, 19741. The nutritional aspect was in- troduced in 1971, and preliminary findings for 1971-1972 have been published. Dietary information is of two types: a 24-h recall of food intake of individuals and information on frequency of use of major food groups. Information to date does not include data on food groups or commodities.

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Role of Animal Products in Human Nutrition All of the food consumption studies have a common basis for cal- culating the nutrient contributions of the food groups. All the studies rely on USDA Agriculture Handbook No. 8, Tables of Food Composi- tion, for converting food intake to nutrient intake. Estimates of nutrient contributions are no closer to actual ingestion of nutrients than are the values given in the tables. Future estimates will be no closer to actual ingestion figures than the values in the Nutrient Data Bank are to the character of the food supply unless reliable methods are developed to measure biologically available forms of nutrients. Other sources of in- formation, including manufacturing, retail store, and marketing statistics on consumption of animal products, were examined as possible sources of information; but none of these had the consistency and completeness necessary to provide reliable indications of change on a national scale. 9 FOODS OF ANIMAL ORIGIN Available data do provide much useful information on consumption of meat and animal products (Table 31. The total consumption of beef and veal per person has increased for several years. On a carcass-weight basis, beef consumption increased from 59.1 lb in 1920 to 63.4 lb in 1950, 85.1 lb in 1960, and an esti- mated 115.4 lb in 1974. Resistance to price increases caused a drop TABLE 3 Consumption of Meat, Chicken, and Turkey (lb per Capita per Year) ~ Lamb and Year Beef b Veal b Pork b Mutton b Chicken c Turkey 1920 59.1 8.0 63.5 5.4 13.7 1.3 1930 48.9 6.4 67.0 6.7 15.7 1.5 1940 54.9 7.4 73.5 6.6 14.1 2.9 1950 63.4 8.0 69.2 4.0 20.6 4.1 1955 82.0 9.4 66.8 4.6 21.3 5.0 1960 85.1 6.1 64.9 4.8 28.1 6.1 1965 99.5 5.1 58.7 3.7 33.4 7.5 1970 113.7 2.9 66.4 3.3 41.5 8.2 1971 113.0 2.7 73.0 3.1 41.4 8.5 1972 116.1 2.2 67.4 3.3 43.0 9.1 1973 109.6 1.8 61.6 2.7 41.4 8.7 1974 115.4 1.9 66.0 2.3 41.5 9.4 a SOURCE: November issues of National Food Situation, published by Economic Research Service, USDA. b Carcass weight. c Ready-to~ook weight.

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10 C. EDITH WEIR to 109.6 lb in 1973. Veal consumption declined from 8 lb in 1920 to l.91bin 1974. Pork consumption has not changed a great deal. Lamb and mutton make up only a small part of the meat intake, and their consumption declined from 5.4 lb in 1920 to 2.3 lb in 1974. Chicken and turkey con- sumption increased mainly during the years 1970-1975. On a ready-to- cook basis, chicken increased from 13.7 lb in 1920 to 20.6 lb in 1950, 28.1 lb in 1960, and 33.4 lb in 1965. It has stayed around 41.5 lb in all but one year since 1970. Turkey increased from 1.3 lb in 1920 to 4.1 lb in 1950, 6.1 lb in 1960, 7.5 lb in 1965, and 9.4 lb in 1974. Per capita estimates of egg consumption showed a steady decline from 334 in 1960 to 294 in 1973. Table 4 shows the quantity of meat, poultry, and eggs purchased per week on a household-use basis in 1965-1966 (USDA, 19671. The average size of households in the 1965- 1966 survey was 3.29 persons. Purchase of meat, poultry, and fish increased 1105to between 1955 and 1965. On an average, the amount of dairy products used by a household in 1965 (Table 5) is 905to of the amount used in 1955. Data on con- sumption of milk and milk products by individuals in 1965 are given in Figure 1. The consumption is expressed as calcium equivalents. In examining the data, one should be mindful of the 1974 recommended dietary allowances (RDA), which are 360 g for infants 0-6 months, 540 g for infants 6 months to 1 year, 800 g for children 1-10 years, and 1,200 g for children 11-18 years and for all adults (NRC, 1974~. For men over age 19, milk consumption decreases from 2-3 cups a day to about 1 cup. Milk provides the recommended amount of calcium for infants, about three fourths of that needed by young children, and one half of that needed by young men until 19 years of age, but less than one half of that needed by young women 11-19 years of age. Less than TABLE 4 Quantity of Meat, Poultry, and Eggs Purchased (per Household per Week) a Meat Total Beef Pork Lunch meat Poultry Total Chicken Eggs 11.05 lb 5.43 lb 3.61 lb 1.42 lb 2.81 lb 2.62 lb 1.84 doz a SOURCE: USDA (~967) .

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Role of Animal. Products In Human Nutrition 11 TABLE 5 Quantity of Dairy Products Purchased (per Household per Week) a Milk Fresh fluid, total Fresh fluid, skim Evaporated Nonfat dry Cream Fresh fluid Ice cream, sherbet Cheese Total Cottage 8.90 qt 0.62 qt 0.62 lb 0.13 lb 0.14 qt 1.36 qt 1.16 lb 0.48 lb a SOURCE: USDA (1967). One third of adult needs for calcium are being met by milk and milk prod- ucts. Girls begin to decrease their intake of milk at 12 years, while their calcium needs are still high, and, as women, continue to consume less milk than is needed to meet their calcium needs. Meat, poultry, and fish intake increases through ages 20-34, then decreases (Figure 21. Highest consumption is during the years 20-34. Over 85% of the persons in each sex-age group used some meat, poultry, or fish during the day of the survey. GRAMS 800 600 400 200 o Quantity per Person in a Day Male and ~ ~ i ~ I I i i 1 1 1 i U11051 1 2 IS ~t-11 12 14 lS 17 1~1, 2~4 ~S-Sl Scow IS 74 IS . ~ 0~! ' AGE IN YEARS FIGURE 1 Calcium contribution to the diet by milk and milk products. Agri- cultural Research Service, USDA.

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12 GRAMS 300 250 200 150 100 50 o C. EDITH WEIR Quantity per Person in a Day Male and _ Female Mile ! :-:-:- :-:-: :-:-: :-:-: :-:-: ....... :-:-: :-:-: :-:-: :-:-: .~ :-:-: :-:- :-:-: :-: .~. ._ .:.:- ~ ..'.'.1 21 ...-. _ ..2. 1 _ Female In AL ... ~ ~ ~ Lo UNDER 1~2 ' ~11 12-14 1~17 1~19 AGE IN YEARS 2~34 As' s~64 6~' IS 0VE! FIGURE 2 Meat, poultry, and fish consumption by men, women, and children in 1965. Agricultural Research Service, USDA. According to USDA "disappearance" statistics (Friend, 1974), foods of animal origin (meat, dairy products, and eggs) supplied the following percentages of calories and specific nutrients to the average American's diet in 1973: energy, 34; protein, 66; fat, 52; calcium, 82; phosphorus, 66;iron, 36; magnesium, 36; vitamin A, 44; thiamine, 39; riboflavin, 70; niacin, 43; vitamin Be, 55; and vitamin B12, 90. These values reflect the great importance of foods of animal origin in our diet. When con- sidering the values for energy and fat, we should remind ourselves that these are disappearance data not values for actual ingestion. They do not take into account the amount of fat removed during trimming, processing, cooking, and so on. AVAILABILITY OF FOOD ENERGY Food energy available per capita (3,290 calories per day) was about 5% lower in 1973 than the 1909-1913 high (3,490 calories) (Fig- ure 31. (These are disappearance data, not estimates of calories in- gested.) However, from 1910 until the late 1960's, available food energy trended downward. It was estimated that 10% fewer calories were available in 1969 than in 1910. The recent increases in calories available in the food supply represent increases in protein and fat (Figure 41. From 1910 to 1973, the proportion of calories derived

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Role of Animal Products in Human Nutrition Per Capita Civilian Consumption OF 1909-13- 150 125 100 75 50 FIGURE 3 Estimated energy sources Agricultural Research Service, USDA. 13 Food energy . Fc t ca vies _ I '_. a-` I I ,--,-R , _ Proteins | ~~ 1 Carbohydrate 1,,,,1,,,,1,,,,1,,,, ... .. , , , , 1 ,, ,, ' 1910 1920 1930 1940 1950 1960 1970 1980 5-YEAR MOVING AVERAGE A PRELIMINARY in the available food supply, 1910-1980. from fat increased from 32% to 42%, the proportion derived from carbohydrate decreased from 56% to 46%, and the proportion derived from protein remained fairly stable at 12%. The amount of protein from animal sources (Figure 5) has increased, and so has the amount of fat from vegetable sources (Figure 6) . Energy from carbohydrate sources has decreased, with starch showing the greatest change. Referring again to the survey of food ingested by individuals (USDA, 1967), milk products provided for adult males 10.7% of the food energy; meat, poultry, and fish, 31.2%; and fats and oils, 6.7% (Table 61. Adult females obtained 11.9% of food energy from milk; 28.9% from meat, TABLE 6 Contribution of Food Groups to Energy Intake a Food Energy ( % ) Food Group Males Females Milk, milk products 10.7 11.9 Meat,poultry,fish 31.2 28.9 Green, yellow vegetables 0.4 0.6 Fats, oils (table fats, other fats and oils) 6.7 6.2 a SOURCE: USDA (~969).

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75 50 25 14 % OF FOOD ENERGY (calories) ~2" ~"2 "I "''2';;; ' ' ' '"' I C. EDITH WEIR ~ ~-~ A\\\\\\\ ~. NOUN ~\\~` `~.~` COCA - `~ - O _ 1910 1920 1930 1940 PER CAPITA CIVILIAN FOOD SUPPLY 1950 1960 1970 1980 1973 PRELIMINARY DATA FIGURE 4 Changes in source of calories in the diet, 1910~1973. Agricultural Research Service, USDA. % 80 60 40 20 O a ................ . ................ ............... ................. ............... ................ ............... a ............... ................ ............... ................ ............... . ................. ............... , ............... ................ ............... ................ ............... ................ ............... ................ .............. ............. -. .............. ................ .............. ................ _ .;;;FLOUR ~ CEREAL PRODUCTSe 2 ............... ..:..:::: A - ............... :: .: : .............. ........ , ............... ~ ~ e Us////// . , ................ ,............... ................ ,............... ............... l ............... ................ ............... ~ Hi* :1"" 1910 1920 1930 1940 1950 1960 1970 1980 CIVILIAN FOOD CONSUMPTION. ~ TOTAL ANIMAL SOURCES. ^1973PRELIMINARY. FIGURE 5 Sources of dietary protein, 191~1973. Agricultural Research Ser v~ce, USDA.

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Role of A nimal Products in Human Nutrition 15 poultry, and fish; and 6.2% from fats and oils. Meat, poultry, fish, and eggs provide about 42% of the total energy ingested. AVAILABILITY OF PROTEIN Overall estimates of available protein have not changed a great deal since 1910 (Figure 31. The overall consumption was highest in 1909- 1913 (102 g), lowest in 1935 (58 g), and for years fluctuated around 95 g. The 1974 RDA for protein were revised downward and are now 56 g per day for men over 23 years (NRC, 19741. RDA'S for other groups also are less. Shifts in the sources of protein have taken place (Figure 51. Over two thirds of the protein in 1973 came from animal products compared with one half in 1910. In 1973, meat, poultry, and fish provided the largest share of the protein, and dairy products the second largest share. Together they provided more than the RDA for an adult man. Higher consumption of beef and poultry accounts for most of the gains in protein from the meat, poultry, and fish group. Beef consump- tion in 1973 was about 50% higher than in 1910. Poultry consumption was almost three times as great. Beef furnished one tenth of the total protein in 1910 and one seventeenth in 1973 (Friend, 19741. Protein provided by dairy products increased from 16% in 1909- 1913 to 24% by the early 1960's but has since decreased 1%. Some dairy foods have steadily increased their proportionate contribution of protein. Cheese and frozen dairy foods are among the gainers. Fluid and evaporated whole milk steadily increased their share from 1909- 1913 into the 1940's. Since then, their share has declined, but in 1973 it remained considerably higher than in earlier years. CONSUMPTION OF FAT The U.S. consumption of fat from food increased from 125 g per capita per day in 1909-1913 to 156 g in 1973- an increase of 25% (Fig- ure 6~. The increase in total consumption of fat has taken place at the same time that the intake of fats from animal sources has been steadily decreasing. Animal sources declined from 104 g in 1909-1913 to 93 g in 1973. This may be somewhat higher in 1974 because of the drop in meat consumption in 1974. The increases in fat from vegetable sources reflect the increased use of margarine and salad and cooking oils (Rizek et al., 19741. (See Figure 7.) During the same period, the proportion of fat consumed as butter, lard, and edible beef fat decreased from almost 75% in

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16 1909-13 1935-39 ~- C. EDITH WEIR (Grams) , __ 2 I/// ~ 1 2 5 Do. ::. . ~ ^~\~\~M ~:.~: ~ ~/~//~ 133 1947-49 ::: ~ ~ At, .s.:~< .~. a.. i~ ~ ~t ~ // 141 1965 1972 1973^ ~Vegeta ble l ~ ~ 145 ~\~\\\-\~\\\\\\\\\\\\\\\\\\\\\\\Nw ////////////////,//~ 156 ~//~/~1156 - ~Animal PER CAPI HA PER DA Y. ~ PREL NINA ~ Y. FIGURE 6 Changes in amount of fat in the diet from vegetable and animal sources. Agricultural Research Service, USDA. % 75 50 25 o AIL 1909-13 1947-49 1957-59 1972^ PER CAPI TA C/ VILIAN FOOD SUPPL Y PRELIMINARY Edible beef fat (indiren use) ~ ~ Lard (direct use) J Butter M argarine Shortening Salad ~ cooking oil FIGURE 7 Contribution of various types of fats and oils to available food supply. Agricultural Research Service, USDA.

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Role of Animal Products in Human Nutrition 17 1909-1913 to about 255to in 1972. Changes in the amount of nutrient fat available from meat sources also occurred during this period (Rizek et al., 1974) (see Figure 81. Again, it is well to remember that these data do not take into account trimming, processing, cooking losses, or plate waste and are considerably higher than the quantities actually in- gested. For data more indicative of individual and household con- sumption, the nationwide food consumption surveys are essential. The most recent data on this basis are from 1965-1966. Since then, many changes have occurred in eating habits and in foods available in the market. The source of dietary fat from dairy products has also changed (Rizek et al., 1974) (see Figure 91. About 25% now comes from cheese, slightly less than 50% from whole milk, and the remainder from other types of milk, cream, and frozen desserts. The contribution by cream decreased from about 25% in 1909-1913 to about 5% in 1972, and the contribution by frozen desserts increased. SOURCES OF VITAMINS AND MINERALS Meat and animal products also are major contributors of vitamin A, providing about 37.5% of the dietary vitamin A in the diets of males 0' an 50 25 ///// ii at at m ~8~ ~ooo X ~ ~ . 1909-13 1957-59 1965 1972 PER CAPITA CIVILIAN fOOD SUPPLY ~ PRELIMINARY Other Fish Pou Itry Lamb, Veal Beef (fat cuts) Pork (lean) FIGURE 8 Contribution of meat, poultry, and fish to nutrient fat in available food supplies. Agricultural Research Service, USDA.

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18 75 50 25 C. EDITH WEIR % ~ ~ ~ _~ _ . ~1 V// ////A E~ , ~Wholes o Cheese Frozen desserts Evaporated Low fat milk Cream 1909-13 1947-49 1957-59 1972 ~ PER CAPITA CIVILIAN fOOD SUPPLY O INCL UDES CONDENSED ~ PREL IMINA R Y FIGURE 9 Contribution of fat from dairy products based on estimates of the civilian food supply. Excludes butter. Agricultural Research Service, USDA. and about 43.2% in the diets of females (Table 71. Per capita esti- mates from the period 1925-1929 to 1973 show the increasing im- portance of the meat group as a source of this vitamin (Figure 10~. We are almost entirely dependent on eggs, dairy products, poultry, fish, and meat for dietary sources of vitamin By, except for fortified foods (Figure 111. The meat, fish, and poultry groups provide about 70% of this vitamin, dairy products 10%, and eggs 10%. Per capita avail- ability of vitamin By in the food supply was 9.7 ,ug per day in 1973, 15% more than in 1909-1913 (Friend, 19741. Vitamin By, for which TABLE 7 Contribution of Food Groups to Vitamin A Intake a Vitamin A Value ( % ) Food Group Males Females Milk, milk products 9.8 8.5 Meat, poultry, fish 27.5 34.7 Green, yellow vegetables 16.7 17.8 Fats, oils (table fats, other fats, and oils) 8.2 6.0 a SOURCE: USDA (~969).

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Role of A nimal Products in Human Nutrition PERCENT 10( 8 60 40 20 n .... ... 1957 59 1925 29 1947 49 19 FATS, OILS ~ OTHER DAIRY EGGS MEAT, POULTRY 8 F I SH SWEETPOTATOES FRU I TS VEGETABLES 1973 FIGURE to Vitamin A contribution from food groups based on estimates of the per capita civilian food supply. PERCENT 80 60 40 20 o 1909-13 1957-59 1973 ''73 D4rA PaEL`alu4Rr. EGGS DAIRY PRODUCTS FISH POULTRY MEAT FIGURE 11 Vitamin BE contribution from food groups based on estimates of per capita food supply. Agricultural Research Service, USDA.

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20 C. EDITH WEIR the 1974 RDA was 3 fig for adults (NRC, 1974), is available in ample amounts in the food supply. Animal sources provided three fifths of the vitamin Be in 1973, but vegetable sources were the main contribu- tors 60 years ago (Figure 12~. Decreased consumption of flour, cereal products, potatoes, and sweet potatoes accounts for most of the decline in vitamin Be from vegetable sources. The total available amount per capita of vitamin Be, 2.25 mg per day in 1973, has not changed ap- preciably since 1909-1913. The 1974 RDA for adults was given as 2 ma. The increasing amounts of thiamine, nboflavin, niacin, and iron available in the food supply within the past IS years have been at- tributed to increased consumption of beef and poultry (Figure 13~. The per capita estimate for iron in the food supply in 1973 was 17.7 mg per day, 16% higher than in 1909-1913 but down from 18.2 mg in 1946 and 18 main 1972 (Friend, 19741. Meat, poultry, andfishpro- vide slightly more iron than grain products (Figure 14~. Together these two groups furnish almost 60% of the iron in the food supply. Beef alone provides only 10% and pork 8%. Liver and other edible offal used in luncheon meats are an excellent source of iron. They amount to 10 or 11 lb per capita and about 3 % of the total iron. How- ever, most of these animal products do not enter the food chain. Calcium is one of the nutrients most likely to be below the RDA in diets. The per capita estimate for calcium in available food sources was PER CENT 80 60 40 20 o GRAIN PRODUCTS VEGETABLES & FR UIT * F . . .. .. . ,,, L'""x All' 1909-13 1957-59 1973 EGGS DAIRY PRODUCTS POULTRY & FISH MEAT TIC INCLUDES DRY BE4NS, PEAS, NUTS, SOYA PRODUCTS. J973 DATA PRELIMINARY. ~ INCLUDES LESS THAN O.S PERCENT frog OTHER FOODS. FIGURE 12 Vitamin Be contribution from food groups based on estimates of the per capita food supply. Agricultural Research Service, USDA.

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Role of Animal Products in Human Nutrition ~ of 1909-13 150 _ 100 50 Per Capita Civilian Consumption _ ~/' ~ O If._._ ,;, - ~ i _ 1 1 1 1 1. IRON RIBOFLAVIN NIACIN THIAMIN 1 ~. 1910 1920 1930 1940 1950 1960 5-YEAR HAVING AVERAGE 21 _ 1970 1980 oPrelimineq FIGURE 13 B vitamins and iron available in the per capita civilian food supply, 191~1973. Agricultural Research Service, USDA. PERCENT 80 60 40 a 111 ' ~ 20 ~ ~ ~ ~ 1925 29 1947 49 1957 59 FIGURE 14 Contribution of iron by food group. 1973 SUGARS AND SWEETS EGGS AND DAIRY MEAT AND POULTRY FLOUR AND CEREAL POTATOES (WH I TE AND SWEET) VEGETABLES AND FRU I T

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22 MILLIGRA MS I 750 500 250 C. EDITH WEIR Per Capita Per Day ~777~ - _ rid- 0~ - ~ LO-DA. OOAA OAA BOA OTHER FROZEN DESSERTS | CHEESE | DRY MILK _ I EVAPORATED ~ CONDENSED MILK LOW-FAT FLUID MILK WHOLE FLUID MILK 1 909-1 3 1 947-49 1 973 FIGURE 15 Contribution of dairy products to calcium available in the food supply. Excludes butter. Agricultural Research Service, USDA. 952 mg per day in 1973, compared with 816 mg in 1909-1913 and the 1974 RDA of 800 mg (Friend, 1974~. Dairy products increased from two thirds of the total supply in 1909-1913 to three fourths in 1973 (Fig- ure 1S). During this period, there were changes in the types of dairy products providing calcium. Although contributions from cheese, frozen dairy products, and nonfat dry milk have increased steadily with in- creased consumption, the contribution from nonfat dry milk has been slowly decreasing since the early 1960's. Meat and animal products also supply major amounts of other nutrients, particularly minerals, and we have grown to depend on these products to supply nutrients for which food sources are not well identi- fied. Animal products are the sole sources of some nutrients and pro- vide half or more of a number of others. This is not to say that the cur- rent high levels of intake are essential to ensure adequate nutntion. The composition of foods and diets can be adjusted to provide good nutn- tion at lower intake levels if economic or health reasons should indicate the need. ACKNOWLEDGMENTS The Consumer and Food Economics Institute, Agricultural Research Service, USDA, furnished much of the information presented in this overview. I am particularly indebted to Berta Friend, who developed the data on contributions of the different food groups to the available amounts of nutrients.

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Role of Animal Products in Human Nutrition REFERENCES 23 Clark, F. 1975. National Studies of Food Consumption and Dietary Levels: An Evaluation of Research in Human Nutrition in the United States. U.S. Depart- ment of Agriculture, Washington, D.C. Friend, B. 1967. Nutrients in U.S. food supply: a review of trends, 1909-13 to 1965. Am. J. Clin. Nutr. 20:907. Friend, B. 1974. Changes in nutrients in the U.S. diet caused by alterations in food intake patterns. Paper prepared for the Changing Food Supply in America Con- ference, sponsored by the Food and Drug Administration, May 22, 1974. Avail- able from Consumer Food Economics Institute, Hyattsville, Md. 20782. NRC (National Research Council), Food and Nutrition Board. 1974. Recom- mended Dietary Allowances. National Academy of Sciences, Washington, D.C. 128pp. Rizek, R. L., B. Friend, and L. Page. 1974. Fat in today's food supply level of use and sources. J. Am. Oil Chem. Soc. 51(6):22~250. USDA. 1967. Household Food Consumption Survey, 1965-66. Food Consumption of Households in the United States, Spring 1965. ARS Publ. No. 62-16. Agri- cultural Research Service, U.S. Department of Agriculture, Washington, D.C. 28 pp. USDA. 1969. Household Food Consumption Survey, 1965-66. Food Intake and Nutritive Value of Diets of Men, Women, and Children in the United States. ARS Publ. No. 62-18. Agricultural Research Service, U.S. Department of Agriculture, Washington, D.C. 97 pp. USDA. 1970. Food: Consumption, Prices, Expenditures, 1968. Agricultural Eco- nomics Report No. 138. Economic Research Service, U.S. Department of Agri- culture, Washington, D.C. 193 pp. USDBW. 1972a. Ten-State Nutrition Survey, 1968-70. Highlights. USDHEW Publ. No. (HSM ) 72-8134. U.S. Department of Health, Education, and Welfare, Washington, D.C. 12 pp. USDBW. 1972b. Ten-State Nutrition Survey, 1968-70. V. Dietary. USDBW Publ. No. (HSM) 72-8133. U.S. Department of Health, Education, and Welfare, Washington, D.C. 340 pp. USDBW. 1974. First Health and Nutrition Examination Survey, United States, 1971-72: dietary intake and biochemical findings. USDBW Publ. No. (HRA) 7~1219-1. U.S. Department of Health, Education, and Welfare, Washington, D.C. 183 pp.