Т е к с т 5. The Role of Red Meat in the Australian Diet

(4.800)

September 2007

Summary

1. Meat has long played a central role in the diet of humans. Human evolution is marked by changes to cranio-dental features and the development of a larger brain balanced by a smaller, simpler gastrointestinal tract. When considered with fossil stable isotope analyses, these developments indicate a growing reliance on the consumption of meat as humans evolved. The extreme reliance on hunted and fished animal foods in more recent hunter-gatherer societies, needed to provide the energy return for survival, is consistent with this view.

2. In Australia, the term ‘red meat’ refers to beef, veal, lamb and mutton meat. The production of quality red meat makes a significant contribution to the economy of the country, the national cuisine and, importantly, the national diet. In nutritional terms, lean red meat is:

• An excellent source of bioavailable iron and zinc, vitamin B12, high biological value protein, niacin, vitamin B6 and phosphorus;

• A source of long-chain omega-3 polyunsaturated fatty acids, riboflavin, pantothenic acid, selenium and, possibly, vitamin D;

• Mostly low in fat and sodium.

3. Lean red meat has an important role to play in diets throughout the life cycle, being crucial for optimal growth and development in childhood and in helping maintain health and wellbeing later in life.

• In childhood and adolescence, iron-deficiency anaemia is associated with serious adverse outcomes that may not be reversible. Children with iron deficiency should be identified and treated at an early stage. As a source of readily absorbable iron and other nutrients, red meat has an important role to play in preventing this situation.

• In adolescence, higher-protein/lower-glycaemic load diets may help ameliorate acne.

4. Higher-protein diets are now a valid option for weight management.

• Dietary protein is more satiating, than carbohydrate, which may assist with compliance.

• Serum triglyceride levels are lowered on higher-protein, lower-carbohydrate diets, especially in those with initial high triglyceride levels. Loss of muscle mass during energy restriction may be minimised.

• Research into the efficacy of higher-protein diets in the management of type 2 diabetes is underway and, in particular, needs to consider long-term effects in those with micro-albuminuria and renal disease.

5. When considering the management of blood cholesterol and the prevention of coronary heart disease:

• Lean red meat is relatively low in total fat, with a higher ratio of polyunsaturated to saturated fatty acids than previously thought.

• Moderate amounts of red meat, provided it is lean, may be included in diets to lower blood cholesterol. Selvedge fat, on the outside of meat, raises blood cholesterol.

• Blood pressure is lowered, when protein (of animal or vegetable origin) replaces refined carbohydrate in diets. Whether this is driven by a beneficial effect of protein or a detrimental effect of carbohydrate remains to be determined.

• The hypothesis, that people with high iron stores are at increased risk of heart disease has not been confirmed in epidemiological studies.

6. With respect to the prevention and management of cancer:

• Evidence, that lean red meat increases the risk for colorectal cancer remains weak and inconsistent. Few individual cohort studies have found an association.

• In meta-analyses of cohort studies, when red meat plus processed meat is considered as a single category, a modest increase in risk of colorectal cancer is observed. However, two out of three analyses of data pooled across cohort studies have found no association.

• Proposed mechanisms, by which red meat or processed meats may affect the risk of colorectal cancer relate primarily to how meat is preserved and cooked. Despite inconsistencies between epidemiological findings and proposed mechanisms, it may be prudent to limit the consumption of processed meats, such as salami and bacon, and to avoid very high-temperature cooking and charring of meat.

• People living with cancer should aim to maintain a healthy weight, be physically active, limit alcohol consumption, and eat more fruit and vegetables. Recommendations for red meat intake are the same as for the general population.

7. Improving the overall diet of a population requires an understanding of cuisine - the cultural use of food. Combinations of core foods make up cuisines, but these combinations are constantly changing. Red meat is a core food in most Australian cuisines.

8. Consumer behaviour is being driven by two trends: an increased understanding of diet as a preventative health tool, and the increasing concern for the integrity of the food. There is an emerging preference for fresh, unprocessed foods, purchased from greengrocers and butchers, then fashioned into meals in the home.(...)