Figure 1: Typical Population Growth Chart
Herbert W. Ockerman1
The Ohio State University
Department of Animal Sciences
Norma Pensel2
ITA-INTA Food Technology Institute
Argentine National Institute for Agricultural Technology
1 For more information contact at: The Ohio State University, 2029 Fyffe Rd., Columbus, OH 43210; 614-292-4317; fax: 614-292-2929.
2 ITA-INTA (Food Technology Institute-Argentine National Institute for Agricultural Technology), CC 77 (1708) Moron, Buenos Aires, Argentina.
To eat meat or not to eat meat? Although humans are omnivorous by design, our digestive and biochemical processes will allow us to survive without eating meat. If humankind can survive without meat, what then are the driving forces for meat eating and its desirability from the perspectives of the individual or the population? Questions arise such as:
These concerns are frequently raised in scientific, social, and political discussions.
It is well documented that the world population is growing, but are the resources to sustain such populations growing at the same rate? As an example, the population of Canada and the United States is almost the same as the world population in year 1 ad. Fortunately food supply has also increased, as since that time more land has been discovered and put into use for food production, particularly in the Americas, Australia, and New Zealand. New technology also permits higher production per unit area. However, the population is rising at one percent per year in developed countries and 2.5 percent in developing countries, and the projected world population for the year 2000 is six billion (Finley and Price, 1994), requiring an 18 percent increase in food production during the 1990s (Avery, 1991). There are no additional large land masses to be discovered that would be available for traditional agriculture. If the world's population growth curve parallels the standard curve for most biological systems, (Figure 1) it is expected that after this rapid increase there will be a decrease in the growth rate until it reaches a balance below the capacity of the environment to sustain that growth (Deatherage, 1975). What does that mean in terms of human population? Does it mean that this balance will be achieved by high mortality due to starvation, or that we will be able to manage an increase in production on existing land, or can the birth rate of Homo sapiens be decreased, or can there be better distribution of the resources without exhausting them? Herbert Ockerman, a professor in the Department of Animal Sciences at The Ohio State University, often quotes a US Secretary of Agriculture who was asked, "Will we be able to produce enough food for the large increase in the future population?" His candid answer was, "If we cannot, they will not be there?"
It is true that animals are inefficient at converting feed calories to animal product calories. However, calculations of efficiency should also take into account the utility of the initial product. Non-ruminants can and often do, consume plant and animal processing by-products that humans will not consume. This recycles calories that otherwise would be wasted, which is excellent efficiency. Ruminants, often considered inefficient by some, are probably the most efficient since their digestive systems can utilize cellulose and fibrous materials, the most abundant raw food material on earth, and even non-protein nitrogen, all of which are less well digested or indigestible by monogastrics, and convert them into well balanced food for people.
Also, a major percentage of the world's land cannot be cultivated due to steepness of the terrain or climatic conditions. The only way it can be harvested is with animals and, again, this is to maximum efficiency for the human population. It is true that animals in some countries are fed grain that could be consumed by humans. However, this will stop when grain becomes more expensive than alternative by-products which today's animal husbandry experts know how to use.
So, far from being inefficient, animals can be very efficient by converting undesirable material to well balanced protein and energy for human consumption.
Variety, diversity of foods, and the taste for them are as wide as those found in the human race, religion, and politics. There are also different ways of looking at food. It can be seen as necessary for our nutritional well-being and/or as contributing to the quality of life. Once our basic nutritional needs have been satisfied, food fulfils other roles. As an example, the public is becoming more demanding for information to assist them in making choices that will permit them to have a longer and healthier lifestyle. Finley and Price (1994) stated that people have many different needs. Agriculturists should, therefore, continue studying not just the food supply and preservation problem, but also the people who demand it. As an example, Indias middle class population (200 million) is expected to continue to increase in the near future, and will want to include more fresh fruits and vegetables, cooking, and high-protein food in their diets (Avery, 1991). Current technology has had more success at increasing the yield of feed grains than of protein meal-type crops.
This would suggest that the items in highest demand in the international food trade will be high-protein foods (Avery, 1991). Proof of that can be seen in the latest figures. Between 1985 and 1995, U.S. exports of beef, pork, and broiler meats, for example, each increased by more than 20 percent, while corn increased only moderately and soybean meal declined slightly (Fuller, 1996).
The word protein comes from the Greek proteios, meaning primary, which suggests the importance of proteins to the nutritional wellbeing of humans (Deatherage, 1975). Proteins are important because they are the only dietary source of amino acids. There are 20 amino acids (Ockerman, 1996), eight of which are classified as indispensable (necessary for maintaining a positive nitrogen balance in humans), though others become critical when members of these eight are lacking or only present at low levels in diets. Our bodies cannot produce these essential amino acids, which are needed in the proper ratio for many biological processes; food is our only source (Stryer, 1988). Meat, eggs, tofu, nuts, and legumes all have high protein content but not all of these foods are equal from a nutritional standpoint. In meat, the essential amino acids are well balanced (in the ratio the body needs) and that is why meat is considered a source of high-quality proteins. The use of meat substitutes (peanuts, peas, soybeans, etc.) on a daily basis requires a good understanding of their amino acid composition (Gallagher and Allred, 1992). If you wish to avoid meat, you need to know the amino acid content of alternative foods in order to be able to combine the right amounts of each kind of food to achieve the necessary balance of the eight essential amino acids. The consequences of consumption will also depend on the physiological and nutritional state of the individual. If a sufficient amount of protein is contained in our intake but disproportionate amounts of essential amino acids are contained in the diet, deficiency, imbalance, or excess of individual amino acids might result (Lawrie, 1970). From this point of view, meat is an ideal food, as it contains all the essential amino acids in the right ratio for maintaining a healthy body. This argument does not, of course, apply to individuals who, for religious or other reasons, choose not to eat meat or for people who have immunological disorders such as allergies to specific foods.
There are two viewpoints one can take when determining what food to produce. The first is to examine the global policies for food supply, which often leads to decisions on whether to grow food crops or cash crops, or whether to produce crops or animals. Food quantity is usually an important criterion. The second alternative is to allow individuals to select what they want to consume, usually based on individual preferences, and then to permit a free market to produce what is demanded. Political and religious entities often use the first approach, whereas individuals are usually concerned more with religion, nutrition and health-related problems, economic resources and capabilities for food preservation, ability of food to be transported, and food safety. Since some religions forbid eating certain meats, there cannot be a global rule for dictating the source of high quality proteins. The nutritional advice given to people of different cultures should take this into account.
As unbalanced protein items are concerned, more than one class of meat substitute needs to be consumed to supply all the essential amino acids in the proper ratio. Thus meat substitutes usually are called low-quality proteins (Gallagher and Allred, 1992). As Lawrie wrote, the striking difference between well-fed and ill-fed people is the greater consumption of animal products by the well-fed population. Protein supply is dramatically lower in tropical countries whose citizens consume primarily roots and tubers than it is in industrialized countries where meat products are consumed in quantity (Lawrie, 1970).
In most countries, meat consumption increases as economic development improves. Besides the obvious politically based interventions and no less important necessity for food in poor countries, economics can modify the diet of a country in other ways. For example, the depreciation (38% relative to other world currencies) of the U.S. dollar's value between 1985 and 1995 allowed foreign countries to import more meat products rather than feed grains (Fuller, 1996). In the case of Japan, diets are being modified by the addition of beef, pork, poultry, and dairy products to traditional meals. In general, it is expected that newly industrialized countries (Malaysia, Thailand, Turkey, etc.) will greatly increase their demand for meat as incomes rise (Avery, 1991).
In 1902, Atwater in the Principles of Nutrition and Nutritive Value of the Food stated that, "Unless care is exercised in selecting food, a diet may result which is one-sided or badly balanced .... and the evils of overeating may not be felt at once, but sooner or later they are sure to appear, perhaps in an excessive amount of fatty tissue, perhaps in general debility, or perhaps in an actual disease." It appears that times have not changed. The 1980, 1985, and 1990 Dietary Guidelines show that the approach is becoming more positive. For example, instead of recommending that individuals avoid too much fat, saturated fat, and cholesterol, the 1990 Guidelines recommended that one choose a diet low in fat, saturated fat, and cholesterol. However, one statement that did not change was, eat a variety of foods (DGAC, 1994). Despite that statement, meat consumption has been at the center of hundreds of discussions, primarily because of the cholesterol content of meat and chronicled link to heart problems, as well as a variety of other health problems. In one of his articles, Allred (1993) ironically states that since strokes are the major cause of death in Japan and that the Japanese have low serum cholesterol levels, then it could be recommended that they increase dietary cholesterol. This leads to the conclusion that diet must be considered on an individual basis, or at least a cultural basis. In other words, the possible benefits of dietary changes will differ for each of us. In nutritional science, the fat consumption issue and its relationship to health is considered to be one of the most important areas of concern and investigation. It is true that excessive fat must be avoided just like excessive sugar or salt, but adequate amounts of fat are essential for health since fat supplies energy, essential fatty acids and fat-soluble vitamins. What is "adequate" will once again depend on the individual. It will vary not only between individuals but also within one individual, requirements differing from normal, for example, during pregnancy, lactation, and vigorous energy-demanding physical activities, or with aging and metabolic disorders.
Apart from the cholesterol problem, the fat issue is far from static. At first there was concern about fats in general, then differences between saturated, polyunsaturated, and mono-unsaturated fats began to be investigated. Later, distinctions were drawn between particular fatty acids. Lauric, myristic, and palmitic fatty acids seem to elevate serum cholesterol and low density lipoprotein (LDL) levels (Keys et al., 1965; Zock et al., 1994), while stearic acid appears not to affect cholesterol or LDL (Bonanome and Grundy, 1988). Polyunsaturated acids moderately reduce cholesterol and LDL levels (Riemersma et al., 1986). There also seem to be differences between different isomers of fatty acids; trans isomers of oleic acid, which are found in partially hydrogenated vegetable oils, tend to elevate serum cholesterol (Mensink and Katan, 1990). Currently the position of a fatty acid in the triglyceride molecule seems to be important. For example, a triglyceride with a saturated fatty acid at position 1 and/or 3 has very different biological consequences from one with the fatty acid at position 2, because absorption of the former type is low (Decker, 1996). If a person is taking a calcium supplement, fat absorption can change, since calcium salts of saturated fatty acids are less well absorbed, and a reduction in cholesterol and LDL levels follows (Dencke et al., 1993). All of these apparent contradictions are very healthy for the research community, and consequently for the population in general, since they generate interest, research, and the search for an answer among scientists and the concerned public alike. In most cases these are not in fact contradictions, rather, they are partial findings often confounded. The pieces of the puzzle are still part of the whole picture necessary to understand the interrelationship between fat and human health. The completion of the puzzle will affect consumers, nutritionalists, educators, and food producers, processors, and distributors. That is why the Food and Agriculture Organization (FAO) states that extreme caution should be taken to avoid overemphasizing one component of an issue since one aspect of a diet-health relationship can affect others (FAO, 1994). Thus consumption of meat, like that of all types of food, should be in moderation. Even water, taken in excess, has ill effects.
Meat has been criticized for lack of fiber, but this can be elevated by consuming it with other food. A variety of dietary items is always recommended. In addition to these concerns it should be pointed out that there are many advantages of consuming meat since it is recognized as one of the most nutritious foods not only because of its high-quality proteins and excellent amino acid balance, and also, in most industrialized nations there are not many food items that can compete with it for the contribution to the diet. Meat is high in quality protein, bioavailable iron, and B vitamins (thiamine, niacin, riboflavin, vitamin B6, vitamin B12). The vitamin B12 requirement which is necessary in humans is primarily provided by meat consumption (Hedrick et al., 1994). The importance of meat in supplying this nutrient has been shown in different publications indicating that low levels of calcium, vitamin D, and B12 in vegetarian lactating women may cause maternal bone demineralization and neurological damage in children (Specker, 1994). Sanders and Reddy (1994) and Sabate et al. (1992) warned that if the perils of some vegetarian diets are not considered, they can result in impaired growth of children. Once again when the diet is limited in one of the six categories of the food pyramid (USDA, 1992) one must be extremely careful in balancing the diet.
Food poisoning has existed for centuries but the scientific community consequently has given us tools to aid in the control of the problem. As our scientific sophistication has improved and possibly as new pathogens have mutated, new concerns over safety arise. E. coli O157:H7 (a newly recognized pathogen), and Listeria monocytogenes (pathogen able to grow at refrigeration temperature) are both fairly heat sensitive and adequate protection can be obtained by proper cooking (Nesbakken and Skjerve, 1996). Bovine spongiform encephalopathy (BSE) is a disease caused by a new type of pathogen (prion) and seems to be related to scrappy in sheep. Consequently it appears that proper rendering (high temperature) of ruminant tissue can eliminate this problem (Prusiner, 1995). Even old problems such as foot and mouth disease seem to be coming under control with previously infected countries being considered free of this virus.
For all the previously stated reasons, and finding no cause except for religious doctrine to avoid eating meat, the decision to eat or not to eat meat should be made by the individual, without biased influence of the press, industry, or the scientific community. For example, Feinstein (1987) suggested that selection of ecological data can change the perception of the relationship between diet and health. He gives as an illustration the "cholesterophobia" era, that was introduced by the interpretation of epidemilogic data from six selected countries (Keys, 1953). The results imply a strong positive relationship between fat calories (as percentage of total calories) and death (per 1000) in males. However, a much less striking relationship (Feinstein, 1987) would have been noted if the epidemiologic data of 16 additional countries (total 22) had been analyzed (Yerushalmy and Hilleboe, 1957) along with the selected six countries (Figure 2).
Dr. Lawrie (1970) also explained that meat is eaten or added to other food to improve its biological value, to add flavor and to give a feeling of satiety or status. The power of liking and wanting to eat meat by carnivorous humans should not be overlooked, since this is a powerful physiological stimulant. Naturally, politics will always play a decisive role in how countries will be fed in the future, now more than ever with globalization. But political doctrines are relatively short term and the individual will in the long run have the last word. Food, when there is no starvation, is more than a bunch of nutrients. Consumption is one of the pleasures of life. Most people know what they like to eat. Therefore, the majority of people like variety and particularly meat, and meat adds variety. Countries that traditionally consume large amounts of meat will reduce their meat intake, trying new products to add variety to their diets. Nations that consume little meat will, as their economy increases, consume more meat for the same reason. The future for meat production, processing, and manufacturing and most important, eating satisfaction and health, looks extremely bright.
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