Influences on Consumption
According to the Council for Agricultural Science and Technology (CAST), an international consortium of 34 scientific and professional societies, a number of factors continue to affect the relationship of diet composition to human health.
“Changes in dietary composition are occurring because of availability, price, disposable income, and advertising,” states Dr. Donald C. Beitz, Distinguished Professor of Agriculture at Iowa State University and chair of the recently released CAST task force report Contribution of Animal Products to Healthful Diets. “And, of course, because of associations of specific dietary constituents to specific degenerative diseases, consumers are concerned about the impact of their diets on personal health.”
In 1995, the U.S. Department of Health and Human Services and the U.S. Department of Agriculture published the pamphlet Dietary Guidelines for Americans. This pamphlet contains the most widely accepted set of recommendations for maintaining good health by Americans of all ages. In following the report’s recommendations to consume less fat (especially fats rich in saturated fatty acids) and cholesterol, Americans have cut down on their intake of certain animal derived foods or eliminated them from their diets altogether and have shifted to other food sources.
Changes in Consumption
Dairy Products. Per capita consumption of dairy products increased until about the mid-1900s, decreased slightly until 1975, and has increased slightly since. Consumption of lowfat milk has increased in recent years, and that of whole milk has decreased. Dairy product consumption is nearly 586 pounds per person annually. Consumption of animal fats, primarily as lard and butter, has decreased to about 10 pounds per year whereas consumption of vegetable fat has risen to about 54 pounds per year.
Red Meat. In women 19 to 50 years of age, mean intakes of beef decreased from 49 grams per day in 1977 to 29 grams in 1987 and 22 grams in 1989-1991. In men 19 to 50 years of age, mean intakes decreased from 80 to 36 grams per day. Pork consumption data in the 1977 and later surveys showed similar declines for men and for women.
Poultry. Per capita consumption of both chicken and turkey meat has increased steadily since the 1940s; the increase has been most pronounced since 1975. Americans consumed 48.8 pounds of chicken and 14.1 pounds of turkey in 1995, as compared with 26.4 and 6.5 pounds, respectively, in 1975. Thus, mean per capita consumption of poultry meat increased 30 pounds, or 91%, from 1975 to 1995 and tended to offset the drop in beef consumption during that period.
According to Beitz, the recent increase in poultry meat consumption probably can be attributed in part to the facts that broiler meat costs less than red meat does and that the number of fried chicken vendors has increased. “Skinned chicken also has become popular,” says Beitz, “as consumer concerns about fat have increased.”
Fish. The availability of fish and shellfish has increased since 1970. Per capita consumption of fish and shellfish increased from 11.7 pounds to 14.9 pounds, or 27%, from 1970 to 1995, with a peak of 16.1 pounds in 1987. Continued focus on foods perceived as healthful especially by older Americans and more fish vendors may explain in part the recent increase in fish and shellfish consumption.
Contribution of Nutrients in Animal Products to a Healthful Diet
Animal derived foods are a primary source of vitamins B6 and B12, riboflavin, niacin, zinc, phosphorus, and calcium. Nearly 70% of dietary protein and nearly 40% of dietary calories are of animal origin, as is between 30 and 40% of dietary thiamin, vitamin A, iron, and magnesium. All dietary cholesterol and about 75% of saturated fatty acids come from animal-derived foods. And the body often can process nutrients in food derived from animals more easily than it can nutrients in food derived from plants.
In the different meats commonly consumed by humans, fat is the component that varies most. Cooking meat usually decreases the content of fat as well as of water. These two principal changes result in a concentrating of constituent protein, minerals, and water-soluble vitamins.
Dairy products are important contributors of dietary protein, calcium, phosphorus, vitamin, and B vitamins, especially riboflavin. Eggs, having a nearly perfect balance of nutrients, are excellent dietary sources of protein, major and trace minerals, vitamins A and D, B vitamins, and essential fatty acids. To the dismay of people concerned about dietary cholesterol, eggs are relatively rich in cholesterol, with 548 milligrams per 100 grams, all of which is in the yolk. By comparison, meats contain less than 100 milligrams of cholesterol per 100 grams.
Aside from the fat and fat-soluble vitamins and iron contained therein and its fatty acid composition, fish muscle has a nutrient composition similar to that of land animal muscle.
The major health concern of consumers in regard to eating animal foods is the content of atherogenic saturated fatty acids such as lauric, myristic, and palmitic acids. “Because these fatty acids constitute only one-fourth to one-third of the total fatty acids in beef and pork fats,” Beitz says, “the overall effects of dietary fats from red meats need closer scientific study. Cholesterol in animal-derived foods is of less concern because compared with highly saturated fats, dietary cholesterol has only minor effects on the plasma cholesterol concentration of most people.”
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