20th century AD

The variety and types of food commodities in the U.S. food supply and the nutrients they provide have undergone significant changes since 1909. In the 1930's, advancements in food-processing technologies introduced into the marketplace canned, frozen, and packaged food items, such as canned soups and vegetables, frozen vegetables and fruits, and packaged cereals. Nationally, the result led to an increase in the availability and shelf life of these foods. Also, in the 1930's margarine was fortified with vitamin A and its precursor beta-carotene (for color), and milk was fortified with vitamins A and D. This was followed in the 1940's with flour and flour products being enriched with thiamin, riboflavin, niacin, and iron. Such events ensured an adequate supply of some nutrients and enhanced the health benefits of the U.S. food supply. During the second half of the century, changes in animal husbandry and marketing practices ensured an adequate supply of red meat and poultry products.

Over the last three decades, changes in the demand for some foods and more variety of others were influenced by several factors: greater ethnic diversity, more elderly consumers, and effective nutrition policy--including mandatory nutrition labeling of food products, revision of grain fortification policy, the issuance of the Dietary Guidelines for Americans, and the release of the Dietary Reference Intakes (DRIs). These events resulted in changes in food supply commodities and nutrients. For example, the 1999 food supply provided a greater variety of grain products, fruits and vegetables, and reduced-fat meats and dairy products than did the 1970 food supply; however, the 1999 food supply also provided record-high amounts of caloric sweeteners and added fats. A change in micronutrient content was also evident in the 1999 food supply; for example, the increased variety and availability of grain products, along with changes in grain fortification policy during this period, were responsible for the record high levels of folate and iron in the food supply.

This article provides information about the availability or consumption of the major food supply food groups and highlights the nutrient availability and contribution of food energy, folate, calcium, and iron from these food groups for selected years--1909, 1945, 1975, and 1999. (1) The article also discusses critical events since 1909 that were responsible for changes in nutrients and food commodities in the U.S. food supply.

The Source and Importance of Food Supply Data

The U.S. food supply series measures the amount of food available for consumption per capita per year and the amount of nutrients available for consumption per capita per day. Extending back to 1909, the U.S. food supply series is the only continuous source of data on food and nutrient availability in the United States. Estimates of food supply nutrients were calculated for the first time during World War II to assess the nutritive value of the food supply for civilian use in the United States and to provide a basis for international comparisons with the food supplies of our allies (U.S. Department of Agriculture [USDA], 1949; Gerrior & Bente, 2001).

The Economic Research Service (ERS) of the USDA calculates annually the amount of food in the United States that is available for consumption on a per capita basis. Food supply data measures national consumption of several hundred basic commodities. For most commodity categories, the available food supply is measured as the sum of annual production, beginning inventories, and imports minus exports, farm and nonfood uses, and end-of-the-year inventories. Per capita consumption is calculated by dividing the available food supply by the total U.S. population as of July 1 each year. An estimated population is used between the years of the decennial census (Putnam & Allshouse, 1999).

Using per capita consumption data and information on the nutrient composition of foods from USDA's Agricultural Research Service, the Center for Nutrition Policy and Promotion calculates the nutrient content of the food supply. Per capita consumption for each commodity is multiplied by the amount of food energy and each of 27 nutrients and dietary components in the edible portion of the food. Results for each nutrient from all foods are totaled and converted to amount of nutrients per capita per day. Nutrients added commercially to certain commodities through fortification and enrichment are also included in the nutrient content of the food supply. Because food supply data represent the disappearance of food into the marketing system, per capita consumption and nutrient estimates typically overstate the amount of food and nutrients people actually ingest.

Per capita food supply estimates provide unique and essential information on the amount of food and nutrients available for consumption. They are useful in assessing trends in food and nutrient consumption over time, for monitoring the potential of the food supply to meet the nutritional needs of Americans, and for examining relationships between food availability and diet-health risk. In particular, food supply data provide useful information to policymakers who are responsible for establishing food and nutrition policy. Recently, ERS developed a method to adjust food supply data for losses and to express the data in terms of Food Guide Pyramid serving recommendations (Kantor, 1998). This method expands the usefulness of food supply data, because the availability of Pyramid serving estimates now allows researchers and policymakers to gauge the availability of food in terms of current dietary guidance and Americans' progress in following the Dietary Guidelines for Americans.

Availability of Food Supply Food Groups

During the 20th century, substantial changes occurred in the availability or consumption of many of the major food groups of the food supply. Many of these changes were linked to advances in food production and technology, Federal standards for enrichment and fortification, the Federal Dietary Guidance system, or increasing consumer demand for nutritionally improved foods.

Meat, Poultry, and Fish Group; Meat Alternates

Consumption from the meat, poultry, and fish group increased from 176 pounds per capita per year in 1909 to 188 pounds in 1945 and to 207 pounds in 1975 (table 1). In 1999 it reached a record high of 245 pounds--up almost 40 percent from 1909. While consumption of red meat reached a record high in 1971 at 162 pounds per person (data not shown), its consumption was much lower in 1999 at 134 pounds per person. Poultry consumption, however, increased dramatically from the mid-1970's--doubling from 47 pounds per person in 1975 to 95 pounds per person in 1999--and thus contributing to the overall increase in availability of this group in 1999. Fish consumption increased somewhat, from 11 pounds per person in 1909 to 15 pounds per capita in 1999.

The consumption of meat alternates-eggs--increased from 35 pounds per person in 1909 to record-high levels in 1945 (and the years immediately following World War II) to 48 pounds per person. During the early and mid-1990's egg use remained stable at about 30 pounds per capita per year (data not shown). By 1999 egg use had increased to 33 pounds per person. The consumption of other meat alternates--legumes, nuts, and soy--generally remained stable over the series with somewhat higher levels consumed in the more recent years. Consumption of legumes, at 13 pounds per person in 1909, gradually dropped to 9 pounds per person in 1999.

Milk and Milk Products

The demand for whole milk has declined; whereas, the demand for lowfat milks (2%, 1%, and skim) and yogurt has increased substantially, particularly in the past two to three decades. From an initial level of 229 pounds per person in 1909 to a record-high level of 344 pounds per person in 1945, whole milk plunged to 72 pounds per person in 1999--about a 79-percent drop, from its record high. The use of lowfat and skim milks, however, doubled from 65 pounds per person in 1909 to 131 pounds per person in 1999. Cheese consumption increased eight-fold between 1909 and 1999--from 4 pounds per capita to 32 pounds per capita (table 1). From 1909 to 1999, increases in ethnic diversity, demand for hard cheeses used in pizzamaking, cheeses used in prepared foods, and the development of the processed cheese market have increased the demand for cheese.

Vegetables and Vegetable Juices

Use of vegetables and vegetable juices in 1999 was 302 pounds per person, a somewhat higher level than the 279 pounds per person in 1975, but substantially lower than the 1909 level of 414 pounds per person. Consumption of vegetables has generally declined since 1909; however, vegetable use increased during World War II--as seen by the 1945 level of 400 pounds per person--because of the popularity of U.S. "victory" vegetable gardens.

The major reason for an overall decrease in the use of fresh vegetables has been the marked decline in the use of fresh white potatoes. In 1909 consumption of fresh white potatoes was 188 pounds per person; in 1999, consumption was 51 pounds per person (data not shown). In the past three decades, consumption of potatoes has shifted from fresh white potatoes to frozen potatoes, with an increase from 19 pounds per person in 1975 to 30 pounds per person in 1999 (data not shown). This shift is associated with the increased popularity of fried potatoes (especially french fries) at fast-food restaurants.

The decline in consumption of fresh vegetables has been slightly offset in recent years by the increased consumption of other fresh commercial vegetables, such as bell peppers, onions, and broccoli. Per capita use of darkgreen and deep-yellow vegetables was similar in 1909 and 1999 at 35 and 36 pounds per person, respectively.

Fruits and Fruit Juices

Consumption of fruits and fruit juices increased by 34 percent, from 173 pounds per person in 1909 to 232 pounds per person in 1999. Per capita availability of citrus fruits and juices nearly quintupled during this time, moving from 16 to 78 pounds per person; however, limited gains in the availability of citrus fruits have occurred since 1945. Since the mid-1970's, the use of noncitrus fruits and melons has generally increased, reaching the level of 153 pounds per person in 1999. Overall, increased availability of fruits is related to increases in juice consumption and the introduction of a greater variety of fruits, including tropical fruits such as kiwi fruit, pineapples, and mangoes into the food supply.

Grain Products; Sugars and Sweeteners

The use of grain products increased to 200 pounds per capita per person in 1999, up by 61 pounds from the 1975 figure. (2) Despite the recent 44-percent increase in grain consumption since 1975, its consumption in 1999 was still 33 percent lower than the 1909 level of 300 pounds per person. In contrast, the use of sugars and caloric sweeteners has skyrocketed, from 84 pounds per person in 1909 to 118 pounds per person in 1975 and then to 158 pounds per person in 1999. The 34-percent increase in average consumption of sugars and caloric sweeteners between 1975 and 1999 reflects huge increases in the consumption of carbonated soft drinks and other sweetened beverages, such as fruit drinks and ades. Use of corn sweeteners, which was minor (less than 5 pounds per person) in 1909, surpassed the use of refined sugar in the mid-1980's and reached an all-time high in 1999 of 85 pounds per person (data not shown).

Fats and Oils

Consumption of fats and oils was 41 pounds per person in 1909 and remained relatively stable through 1945. Then it increased 33 percent, from 42 pounds in 1945 to 56 pounds in 1975, and increased another 30 percent from the 1975 level to 73 pounds in 1999--78 percent more than in 1909. Over the series, a shift from the use of fats and oils from animal sources to vegetable sources has occurred and is due to substantial increases in the use of vegetable-fat products, such as margarine, shortening, and salad and cooking oils. The increase in total fats and oils, especially in the last three decades, probably resulted from the greatly expanded use of fried foods by the fastfood industry and food service outlets, as well as the increased use of salad oils on salads consumed both at home and away from home (Gerrior & Bente, 2001).

Availability and Contribution of Selected Nutrients

Food Energy

Food energy (kilocalofies), the energy released from the metabolism of foods, allows the production and maintenance of body tissue cells. Over the food supply series, energy levels have been as low as 3,100 (in 1975) kilocalories (kcal) and as high as 3,800 (in 1999) kcal per capita per day (table 2). In 1909 the energy level was 3,500 kcal per person; in 1945, it was 3,300 kcal per person. Energy levels continued to drop until reaching a low of 3,100 kcal per capita per day in the early 1950's through 1965 and rose between 1965 and the early 1970's (data not shown). They dropped again to 3,100 kcal in 1975. These lower levels of food energy are associated with a decreased consumption of grain products (Gerrior & Bente, 2001). By 1999 food energy levels reached a high of 3,800 kcal per capita per day.

Various food groups have fluctuated in their contribution to the food energy in the food supply; however, grain products have consistently provided a major share--although at fluctuating levels (fig. 1). The share of kilocalories from grain products decreased from 39 percent in 1909 to 24 percent in 1999. The 1999 share, however, is higher than its 1975 share (20 percent). The fats and oils group and the sugars and sweeteners group have simultaneously and similarly increased in their share of kilocalories. Both contributed 12 percent in 1909 and 13 percent in 1945. Fats and oils provided 18 percent of the kilocalories in 1975 and 19 percent in 1999; sugars and sweeteners provided 19 percent of the kilocalories in 1975 and 20 percent in 1999. The meat, poultry, fish, and meat alternates group fluctuated in its share but provided the same percentage of kilocalories available in 1999 as in 1909 (19 percent). The milk and milk products also fluctuated in its percentage share of kilocalories but provided about a 9-percent share in both 1909 and 1999.

[FIGURE 1 OMITTED]

Folate

Folate functions as a coenzyme and is essential for the biosynthesis of nucleic acids and normal maturation of red blood cells. Low levels of serum folate have been associated with elevated serum homocysteine, an independent risk factor for vascular disease and, during pregnancy, it is associated with the increased risk for neural-tube defects. Among the selected years studied, folate levels before 1999 ranged from 323 to 347 micrograms (gig) per capita per day. The lowest level of folate, 268 [micro]g per capita per day, occurred in 1965-66 (data not shown) and was caused by a decreased use of vegetables, mostly potatoes, and grain products. The highest level of folate, 641 [micro]g per capita per day in 1999, was mainly due to fortification of flour and breakfast cereal (table 2).

Vegetables were the leading source of folate in the food supply prior to 1974--accounting for 28 percent of the folate in 1909--whereas grain products provided 25 percent for the same year. In 1999 grain products were the leading contributors of folate, providing almost two-thirds of the total folate in the food supply (fig. 2). This increase, beginning in 1998, was due to fortification of flour and breakfast cereal with this nutrient. The meat, poultry, fish, and meat alternates group provided about one-third of the total folate in the U.S. food supply for the years 1909, 1945, and 1975, but by 1999 its share had dropped to 17 percent. Over the years, the contribution of folate from fruits has fluctuated. The 1999 contribution was almost double that of 1909, increasing from 4 to 7 percent. This reflected the increased use of fresh and processed citrus commodities. The contribution of milk and milk products to folate in the food supply dropped from 6 percent in 1909 to 4 percent in 1999.

[FIGURE 2 OMITTED]

Calcium

Calcium is essential for the formation of bones and teeth; its requirements are highest during adolescence, later adult years, pregnancy, and lactation. Calcium is very important from a public health perspective because inadequate intake of calcium may increase the risk of osteoporosis, a condition in which decreased bone mass weakens bones and leads to fractures.

The amount of calcium available in the food supply has shifted over the years. Calcium levels dropped from 760 milligrams (mg) per capita per day in 1909 to 690 mg in 1916 (data not shown), primarily due to decreased use of whole milk during that time (fig. 3). Increased use of whole, canned, and dried milk and cheese resulted in an increase in calcium levels by 42 percent between 1909 and 1946 when calcium reached a peak value of 1,080 mg per capita per day (data not shown). This increase is attributed to the production levels associated with the years around World War II. From the mid-1940's through the 1970's to the early 1980's, calcium levels generally declined. Since then, however, levels have tended to increase because of greater use of lowfat milks, yogurt, and cheese (fig. 3, table 2).

[FIGURE 3 OMITTED]

Dairy products have always been the predominant source of calcium in the food supply. While they remain so, a shift within the dairy group, that is a decreased use of whole milk and an increased use of lowfat milks, has occurred over the years (fig. 4). In 1909 whole milk accounted for 44 percent of the calcium in the food supply; in 1999 it accounted for 11 percent only. Even though the share of calcium contributed by lowfat milks has increased, it does not completely compensate for the calcium loss due to the decreased use of whole milk. The share of calcium provided by cheese was more than six times higher in 1999, at 25 percent, than in 1909, at 4 percent. The share of the vegetable group contributing to calcium in the food supply has generally declined, dropping from 9 percent in 1909 to 7 percent in 1999 (fig. 4).

[FIGURE 4 OMITTED]

Iron

Iron is found in all cells of the body. As a component of hemoglobin in the blood and myoglobin in the muscles, iron carries oxygen. Among Americans, iron deficiency anemia is the most common nutritional deficiency, with infants, adolescents, and women of childbearing age having the highest risk of developing anemia. Their greater need for iron, due to rapid growth or excessive blood loss during menstruation, usually cannot be met by dietary intake alone.

Iron levels increased from 14.2 mg per capita per day in 1909 to 16.4 mg in 1945 (table 2). By 1973 iron levels had dropped to 15.4 mg (data not shown). After changes in iron fortification in 1974, iron levels in the food supply increased to 16.4 mg per capita per day in 1975 and rose to 23.6 mg per capita per day in 1999. The increased use of enriched grains and fortified ready-to-eat breakfast cereals is the main reason for the higher iron levels in the food supply.

Even before the enrichment of white flour, the predominant source of iron was grain products. In 1909 grain products provided 34 percent of the iron in the food supply (fig. 5). When the use of grain products dropped, its iron share declined until the enrichment of flour began in the 1940's. With the enrichment of flour and fortification of breakfast cereals, grains remained the main source of iron despite the drop in their consumption. Grain use increased in the 1980's; by 1999, grain products accounted for over 50 percent of the iron in the food supply. After grain products, the meat, poultry, fish, and meat alternates group--particularly red meats--has ranked second as a source of iron throughout most of the years. This group provided 38 percent of the iron available in 1909 and 25 percent in 1999. The vegetable group, specifically white potatoes, was an important source of iron in earlier years. However, the share of iron from vegetables declined when the use of white potatoes declined. In 1909 the vegetable group furnished 18 percent of the iron in the food supply; in 1999, that share dropped to 10 percent. Other groups provided minimal iron to the food supply: fruits provided 3 percent over the course of the series; the dairy group, 2 percent; and "other foods," not more than 10 percent.

[FIGURE 5 OMITTED]

Conclusion

During the 20th century, advances in food production and fortification technologies resulted in more foods and nutrients being in the U.S. food supply. Americans should expect the food supply to continue to provide a safe source of nutritious foods and to reflect changes in marketing practices, food technologies, and nutrition knowledge. The U.S. food supply will also continue to reflect consumer demand for foods based on nutrition knowledge.

Table 1. Foods available in U.S. food supply (per person per year), by
major food group for selected years (1)

                                          1909   1945   1975   1999

                                              Pounds per person

Meat and meat alternates                   228    257    261    298
Meat, poultry, and fish                    176    188    207    245
  Red meat                                 148    153    148    134
  Poultry                                   17     26     47     95
  Fish                                      11     10     12     15
Meat alternates
  Eggs                                      35     48     35     33
  Legumes, nuts, and soy                    17     20     19     21
  Legumes                                   13     11      7      9

Milk and milk products                     345    552    453    502
  Whole milk                               229    344    181     72
  Lowfat milks                              65     40     60    131
  Cheese                                     4      9     19     32
  Other dairy                               29    130    129    138

Vegetables and vegetable juices            414    400    279    302
  White potatoes                           188    120     82     87
  Deep-yellow and dark-green vegetables     35     46     25     36
  Other vegetables                         145    174    127    134
  Tomatoes                                  46     61     44     45

Fruit and fruit juices                     173    207    189    232
  Citrus fruits                             16     71     77     78
  Noncitrus fruits                         157    135    112    153

Grain products                             300    204    139    200

Sugars and sweeteners                       84     92    118    158

Fats and oils                               41     42     56     73
  Butter                                    18     11      5      5
  Margarine                                  1      4     11      8
  Shortening                                 8      9     17     22
  Lard and beef tallow                      13     12      3      6
  Salad, cooking, and other oils             2      6     20     32

Miscellaneous foods                         10     20     13     13

(1) See box for information on weight basis.
Table 2. Nutrients available (per person per day) in U.S. food supply
for selected years

Nutrient                      Unit   1909    1945    1975    1999

Food energy                   kcal   3,500   3,300   3,100   3,800
Carbohydrate                    gm     500     425     381     500
Dietary fiber                   gm      29      26      19      24
Protein                         gm     101     104      92     111
Total fat                       gm     122     138     144     164
Saturated fat                   gm      52      55      49      52
Monounsaturated fat             gm      47      54      57      70
Polyunsaturated fat             gm      13      18      27      34
Cholesterol                     mg     450     540     420     430
Vitamin A                   mcg RE   1,240   1,540   1,590   1,780
Carotenes                   mcg RE     430     560     590     800
Thiamin                         mg     1.6     2.1     2.3     3.0
Riboflavin                      mg     1.9     2.6     2.6     2.9
Niacin                          mg      19      22      26      33
Vitamin [B.sub.6]               mg     2.2     2.0     2.0     2.5
Folate                         mcg     323     347     330     641
Vitamin [B.sub.12]             mcg     8.4     9.3     8.5     8.1
Vitamin E             mcg alpha-TE     7.2    10.5    14.0    17.8
Vitamin C                       mg      98     119     114     132
Calcium                         mg     760   1,070     870     990
Phosphorus                      mg   1,500   1,670   1,420   1,690
Magnesium                       mg     390     400     320     390
Iron                            mg    14.2    16.4    16.4    23.6
Potassium                       mg   4,060   4,270   3,450   3,890
Zinc                            mg    13.7    13.3    13.1    15.5
Copper                          mg     2.0     1.9     1.7     2.0
Selenium                       mcg     169     150     136     178

(1) The initial and final years of the food supply series for which data are currently available are 1909 and 1999. In 1945 increased food production of a number of foods is associated with World War II and advances in enrichment and fortification during the 1930's and early 1940's; 1975 reflects changes in enrichment policy for grain and cereal products made in the early 1970's.

(2) The record-level low of 129 pounds per person of grain products was in 1972.

References

Gerrior, S., & Bente, L. (2001). The Nutrient Content of the U.S. Food Supply, 1909-97. Home Economics Report. No. 54. U.S. Department of Agriculture, Center for Nutrition Policy and Promotion.

Kantor, L.S. (1998). A Dietary Assessment of the U.S. Food Supply: Comparing Per Capita Food Consumption With Food Guide Pyramid Serving Recommendations. Agricultural Economic Report No. 772. U.S. Department of Agriculture, Economic Research Service.

Putnam, J.J., & Allshouse, J.E. (1999). Food Consumption, Prices, and Expenditures, 1970-97. Statistical Bulletin No. 965. U.S. Department of Agriculture, Economic Research Service.

U.S. Department of Agriculture, Bureau of Agricultural Economics. (1949). Consumption of Food in the United States, 1909-48. Miscellaneous Publication No. 691. Washington, DC.

RELATED ARTICLE: U.S. food supply: foods in pounds per person by major food group for the years, 1909, 1945, 1975, and 1999.

Pounds of food per capita per year by major food groups in the U.S. food supply were adapted from data published in the ERS series, "Food Consumption, Prices, and Expenditures" (Putnam & Allshouse, 1999). The adaptations allow for the determination of nutrient estimates from the major commodity groups and the percentage contribution by nutrients for each of these groups.

Pounds of most foods are totaled on the basis of their retail weights to achieve consistency in grouping different foods. Summing dissimilar forms of foods--such as liquids, solids, and concentrated products--makes it difficult to interpret changes in these data. Because of increased processing of foods over the years, pounds of food measured in equivalent weights are more appropriate for analyses of food trends. Totals for other milk products, total dairy products, and total sugars and sweeteners are measured in equivalent weights. However, caution must be used in interpreting the pounds per capita for other foods in this report to avoid misleading implications from either their levels or trends. For information on levels of individual foods, see the references.

Meat: Reported as fresh retail cut equivalent, which includes all meat cuts obtained from a carcass and trimmed for retail sale. Includes game, organ meats, and fat cuts of pork.

Poultry: Reported as ready-to-cook weight. Ready-to-cook poultry weight is the entire dressed bird, which includes the bones, skin, fat, liver, heart, gizzard, and neck. Includes game birds.

Fish: Reported on edible-weight basis, which excludes such offal as bones, viscera, and shells. Includes game fish.

Eggs: Reported as shell-equivalent weight, which includes shell eggs and the approximate shell-egg equivalent of dried and frozen eggs.

Other milk products: Includes creams, evaporated and condensed milks (canned and bulk), dry milk, whey, yogurt, sour cream, eggnog, and ice cream and frozen desserts.

Reported as calcium-equivalent weight, which is the amount of fluid whole cow's milk that has the same quantity of calcium as other milk products. For example, the calcium equivalent of 1.5 pounds of cheddar cheese is calculated as follows:

1. Derive calcium conversion factor.

calcium in 1 pound cheddar cheese/calcium in 1 pound fluid milk = 3,275 mg/560 mg = 5.85

2. Multiply amount of cheddar cheese by calcium conversion factor.

1.5 pounds x 5.85 = 8.78 pounds

Total milk products: Reported as calcium-equivalent weight.

Total grain products: Includes wheat flour, rye flour, rice, corn flour, corn meal, hominy and corn grits, oat products, barley products, and ready-to-cook and ready-to-eat breakfast cereals.

Lard and beef tallow: Excludes use in margarine and shortening.

Total fruits: Reported as product weight except for concentrated juices, which are on a single-strength basis.

Total other fresh vegetables: Includes dark-green and deep-yellow types, tomatoes, and others.

Miscellaneous: Includes instant and regular coffee reported on roasted basis; tea reported as leaf equivalent; cocoa reported as chocolate-liquor equivalent of cocoa beans, which is what remains after cocoa beans have been roasted and hulled; and spices.

Lisa Bente, MS, RD
Shirley A. Gerrior, PhD, RD

U.S. Department of Agriculture
Center for Nutrition Policy and Promotion

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