Fat in animal products: facts and perceptions

Abstract

Early research in man at the end of the fifties and beginning of the sixties indicated that the composition of dietary fat influenced plasma cholesterol levels. In effect this research showed that plasma cholesterol was raised by saturated fatty acids (SFA), was lowered by polyunsaturated fatty acids (PUFA) and was not influenced by monounsaturated fatty acids (MUFA). Within the SFA it was also observed that the greater the chain length, the lesser the cholesterol raising effect. A quantitative relationship between the change in blood cholesterol (AC) resultant from changes in the percentage energy from SFA (AS) and PUFA (AP) was established as AC = 1-3 (2AS -AP). For the ensuing tivo decades this association dominated nutrition education programmes with the message that 'saturates or animal fats raise blood cholesterol and polyunsaturates or vegetable oils lower blood cholesterol'.In the 1980s it became evident that the two main fractions of blood cholesterol yielded different risks for coronary heart disease. Low-density lipoprotein (LDL) cholesterol raised the risk and high-density lipoprotein (HDL) cholesterol lowered the risk. Earlier work on the qualitative effect of dietary fat was now repeated to examine the direction of change of the LDL and HDL subfractions of plasma cholesterol. Broadly speaking these data showed that SFA raised LDL cholesterol and had little effect on HDL cholesterol. PUFA lowered LDL cholesterol but when the intake was high, also lowered HDL cholesterol. Whilst this summarizes events leading up to current thinking on dietary fats and blood cholesterol, it is likely in the near future to be linked to another area of research involving the antioxidant vitamins and pro-vitamins (vitamin E, vitamin C and ^-carotene). A growing body of data in the literature indicates a protective effect of antioxidant vitamins in epidemiological trials.Notwithstanding these findings, it is likely that dietary advice will continue to seek a lowering of SFA intake. PUFA intake will be capped and MUFA intake will be a more acceptable alternative. However, with increasing emphasis on antioxidant vitamin status, such advice is likely to be coupled with advice on increased consumption of fruit and vegetables.

Modification of Fatty Acid Composition in Meat Through Diet: Effect on Lipid Peroxidation and Relationship to Nutritional Quality – A Review

“…Research on heart disease in humans has tended to implicate high intakes of saturated fat and cholesterol as contributory factors with a possible protective effect of polyunsaturated fat and a neutral effect of monounsaturated fat [45]. Overall, the advice to consumers has been to control the level of energy consumed as fat to under 35% and in particular, to limit saturated fats to 10%of energy intake [13].…”

“…Overall, the advice to consumers has been to control the level of energy consumed as fat to under 35% and in particular, to limit saturated fats to 10%of energy intake [13]. It is also recommended that the proportion of short-and medium-chain saturated fatty acids be reduced and that intake of n-6 fatty acids be reduced relative to n-3 [45].…”

Producing tender and flavoursome beef with enhanced nutritional characteristics

“…Such a perception has probably contributed to the decline in beef consumption, since medical authorities worldwide recommend that energy intake from fat should not exceed 30-35 % total energy intake, that energy intake from SFA should not exceed 10 % total energy intake, and that energy intake from monounsaturated fatty acids and PUFA should be approximately 16 and 7 % total energy intake respectively. Furthermore, an increase in n-3 PUFA consumption such that n-6:n-3 PUFA is 4:1 has also been recommended (Gibney, 1993;Department of Health, 1994; US Department of Agriculture, 2000). Such recommendations have provided impetus to develop strategies to alter the total fat concentration and the fatty acid composition of beef fat to be more compatible with consumer requirements.…”

Factors influencing fatty acids in meat and the role of antioxidants in improving meat quality

“…In the UK recent recommendations are 35 % of energy for fat and 10 % of energy for saturated fatty acids (Department of Health, 1994). Within these general guidelines more particular advice is to reduce the intake of short-and medium-chain saturated fatty acids and the intake of n-6 polyunsaturates relative to n-3 (Gibney, 1993). Although it is the dietary balance of fatty acids in the total diet which is physiologically important, attempts have been made with many individual foods to change them in line with the new dietary guidelines in order to make them more attractive to consumers.…”