The functionality of meat

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Typical Western omnivorous diets over the last 40 years have been relatively high in protein and fat with insufficient dietary fibre, fruit and vegetables. Meat intake is by definition the key difference between vegetarian and omnivorous diets, thus comparative studies have tended to exaggerate the health benefits of a vegetarian diet so reinforcing a negative health image for meat. It has long been recognized (Burr, 1988) that although vegetarianism seems to confer some protection against heart disease, it is not clear if this is due to abstinence from meat or high consumption of vegetables. Meat intake has provided a marker for a generally 'unhealthy' diet in the past (American Dietetic Association, 1993; COMA, 1991; Sanders and Reddy, 1994; Thorogood, 1994). Furthermore, vegetarians have tended to be more health conscious, they traditionally smoke less, consume less alcohol, tea, and coffee, and tend to exercise more, thus their good health could be attributed to any or a combination of these habits. CHD and cancer are mul-tifactorial; diet is one factor playing a role in these conditions, but diet alone is a very broad term, because within diet there are protective and causative factors. Comparing current omnivorous and vegetarian diets shows that the meat content of the former is not responsible for its higher fat content. Australian research has shown that when the meat component was removed from an omnivore diet, the remaining part of the diet was still significantly higher in total fat, saturated fat and cholesterol than was a vegetarian diet (Li et al, 1999). This suggests that the overall diet rather than the meat is responsible for these diet characteristics.

The significance of meat to nutrient intake depends on the importance given to meat in an individual's, or in a society's diet and culture. With a limited range of foods available in primitive societies throughout history, meat provided a concentrated source of a wide range of nutrients (Davidson and Passmore, 1969; Sanders, 1999). Considering the diet of modern man, where meat is excluded within traditional vegetarian cultures, the nutrients it provides can be supplied from a combination of other foods and this appears at least adequate, provided the diet is not too restrictive and dependent on nutritionally inferior staples such as maize or cassava (Sanders, 1999). With the range and abundance of foods available to developed societies today, the nutritional significance of any one food is reduced.

Traditionally, the vegetarian was likely to consume a wider range of foods than the meat eater. Consequently, vegetarians in Europe and North America historically had similar energy intakes to meat eaters and greater intakes of vitamins B1, C, E, folic acid, b-carotene, potassium and fibre (Sanders, 1999). Today, vegetarianism cannot be assumed to provide a favourable fatty acid intake. Comparative studies of vegetarian and omnivorous children surveyed from 9 to 17 years old found that saturated fat intakes were no lower in the vegetarian children (Nathan et al, 1994; Nathan et al, 1997; Burgess et al, 2001). There was no significant difference between energy intakes and the percentage energy from fat, or saturated fat intakes between vegetarian and omnivore adolescents in northwest England (Burgess et al, 2001). Vegetarian women have lower zinc intakes and status than their omnivore counterparts (Ball and Ackland, 2000). A recent study in Australia showed vegetarians had a lower intake of beneficial very long chain n-3 PUFAs (Li et al, 1999). A study comparing meat eaters with vegetarians has shown that levels of plasma homocysteine, an independent risk factor for heart disease, among vegetarians were significantly higher than their omnivore counterparts, and this was correlated with a lower intake of vitamin B12 among the vegetarians (Mann et al, 1999; Krajcovicova-Kudlackova et al, 2000; Mann 2001b). Vegans have significantly lower intakes of protein, vitamin D, calcium, and selenium but no difference in energy and iron intakes from those of omnivores and the vegans have significantly lower vitamin B12 blood concentration (Larsson and Johansson, 2001).

Modern eating habits contribute to erosion of the traditional vegetarian diet in developed countries because there is now a greater dependence on vegetarian convenience foods, coinciding with increased availability and choice. Whilst vegetarian convenience foods may appear attractive in terms of health as well as for ease and speed of preparation, they are not necessarily of superior nutritional value compared with meat-containing equivalents. There is wide variation in the fat content of vegetarian products, ranging from 2% to 58%, with nearly a third supplying more than 50% of their energy from fat (Reid and Hackett, 2001).

Excluding meat whilst paying little attention to selecting appropriate alternative food combinations, to ensure adequate nutrients are supplied, is cause for concern, especially in children and adolescents. Today's busy lifestyles give rise to more erratic dietary practices making it easier to obtain all nutrients required for health by including meat as a component of the diet. The time spent planning and preparing meals is minimal and an increasing proportion of our daily food intake is consumed outside the home as snacks and quick meals. NFS data suggest that in 1998 28% of total expenditure on food and drink was outside the home (MAFF, 1999). Data on the dietary intakes and nutritional status of young people aged between 4 and 18 years in Britain show that energy intakes of young people are now approximately 20% below estimated average requirements (EAR) for age. Growth patterns suggest such intakes are adequate and merely reflect the corresponding lower activity levels of youngsters today, which in itself is a concern. Reduced energy intakes must increase the emphasis on a more nutrient dense diet, particularly in growing children. The survey has recorded intakes of iron, zinc and copper below the RNI particularly in older girls (Gregory et al, 2000). It is possible that the recorded lower meat intakes are partly responsible for this. The decision to become vegetarian should be accompanied by adequate nutritional information and education. Despite popular opinion, vegetarianism per se does not guarantee a nutritionally adequate diet. Conversely, using meat as a significant protein source in the diet provides a concentrated nutrient supplement, thus ensuring the diet is nutritionally adequate (Department Of Health, 1994a; Millward, 1999). The potential for producing nutritionally superior, convenience products, that include meat as a functional ingredient, is enormous and deserves more thorough exploitation.

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