Scientists Seek to Improve Fat Composition of Red Meat

22 Jan 2015 --- In the Western world, cardiovascular disease (CVD) is the main cause of mortality and it has been largely attributed to the amount of saturated fat in the diet of Western consumers. This type of fat, which has been reported to cause atherosclerosis, a narrowing of the arteries, is mainly derived from animal sources, such as red meat, butter and cheese.

A possible relationship between CVD and the quality of dietary fat intake has been established with further studies linking the incidence of developing colorectal cancer to red meat consumption. This has resulted in the development of dietary guidelines, which emphasize the need to reduce fat and specify recommended dietary fat intakes for each class of fatty acid. Reports published by a panel of leading scientists on behalf of the World Cancer Research Fund and the American Inst. of Cancer Research further recommend ingesting no more than 500g of red meat per week with limited processed meats.

Although public awareness has improved, the message regarding meat consumption is often misleading. Health professionals recommend moderate red meat consumption, because of its highly saturated fatty acid (SFA) content. However, there is now a greater understanding of possible confounding factors in previously reported studies, which found significant but weak incidences in epidemiological terms for the risk associated with developing heart disease and colorectal cancer due to high red meat consumption.

Health-conscious consumers following dietary fat recommendations require meat that is low in saturated fat with preferably high levels of long-chain omega-3 fatty acids. The best type of meat for this purpose is fish, while white meat such as chicken provides less saturated fat.

Scientists are now looking at ways to reduce the saturated fat content of red meat such as lamb so that consumers can enjoy this type of meat without the health concerns it usually carries.

One such study, ‘Opportunities and Implications of Pasture-Based Lamb Fattening to Enhance the Long-Chain Fatty Acid Composition in Meat’, published this month in Comprehensive Review in Food Science and Food Safety, examines the potential to enhance lipid composition through pasture-feeding. The role of fatty acids in plant and ruminant metabolism is discussed to highlight the complexity of ruminal digestion when trying to enhance fatty acids in meat.

Generally, ruminants that consume pasture diets have been shown to produce a more desirable fatty acid composition than those fed grain and offer potential to be further enhanced by using specific plant species. Elevated polyunsaturated fat content in meat, however, tends to increase susceptibility to oxidation, which influences other meat quality characteristics including shelf-life and color. The use of specific plant species may mitigate these negative effects due to vitamin E or other antioxidants in these plants, which protect polyunsaturated fats from oxidation. When assessing the potential of plants as a natural dietary fat source, consideration must be given to environmental influences on plant fatty acid composition to ensure consistent production of meat products with high nutritive value under a range of management practices. Another consideration is the potential impact of climate change on plant fatty acid composition, and the potential implications of this for meat quality.

Complex metabolic processes in the rumen constrain the ability to improve fatty acid content in meat products to meet recommendations for daily fat intake. Although an animal's diet significantly influences the composition of meat, most success has been achieved through encapsulation and protection against rumen biohydrogenation. However, in many areas this is not profitable and livestock are more economically finished on pasture. Pasture naturally enhances the proportion of long-chain fatty acids in meat and often enriches the meat with antioxidants, which is especially important for meat quality characteristics when there are high levels of PUFA. 

Red clover has been identified as a promising dietary source to elevate long-chain fatty acids in meat, as it does not undergo significant biohydrogenation in the rumen. However, studies on plants have demonstrated that fatty acid composition is largely determined by species, cultivar, climate, and management, which may or may not confound the effects seen in grazing animals. Therefore, it would be beneficial to assess whether there are other plant species that have the potential to favorably alter the fatty acid composition of meat, and to determine whether the effects of environment and seasonality on plant fatty acid contents are replicated in meat.

There is clearly a need for more research in this area, which will enable consumers to make more informed choices, but also give meat producers the tools they need to improve the dietary composition of their products and make them more desirable to the health-conscious consumer.