Consumers have shown considerable interest in “healthy fats” and “bad fats” in recent years. The potential health attributes of conjugated linoleic acid (CLA) and omega-3 fatty acids have led to considerable media focus, marketing opportunities and consumer confusion.
Stores now place omega-3 labels on fish, yogurt, eggs and bagels. Beef contains both omega-3’s and CLA’s, but you will not find these labels on beef products because the current levels of omega-3’s do not meet the minimum requirement for a nutrient content claim, and there is no official health claim for CLA in Canada.
CLA’s are naturally produced trans fats that are primarily found in animal products. CLA has been called “the healthy trans fat” because some lab animal studies have shown that it may help reduce the risk of cancer, obesity and heart disease, and may improve immune function. The overall benefits and risks that CLA’s may pose to human health are not entirely clear.
Health Canada has recommended that the trans fat content of pre-packaged foods and food service menu items not exceed 5% of total fat content due to concerns that they may raise cholesterol levels and the risk of cardiovascular disease. However, fresh retail beef and other ruminant products are not included in this recommendation, primarily because trans-fats are naturally occurring in fresh beef and milk.
Omega-3’s are a family of at least nine different fatty acids. Omega-3’s are found in a very wide range of plant and animal products. Products containing omega-3’s can have a nutrient content claim, provided the product contains at least 300mg of omega-3 per serving (in Canada, one serving of beef is 75g).
Three members of the omega-3 family, ALA, DHA and EPA, have received particular attention. ALA is an essential fatty acid, meaning that it must come from the diet because the body cannot manufacture it. DHA and EPA can either come from the diet, or be manufactured in the body from ALA. DHA has a “biological role” claim in Canada due to its role in brain, eye and nerve development. EPA is believed to improve heart health.
ALA is far and away the most abundant omega-3 in beef, and very little of the ALA that a person consumes will be converted to either DHA or EPA. The levels of DHA and EPA are much higher in fish than beef.
Testing Feeding Strategies to Increase CLA and Omega-3’s Levels
Researchers have examined various feeding strategies to determine whether it’s possible to increase levels of CLA and omega-3’s in beef to consistently meet labeling requirements in a cost-effective manner without negative side-effects.
In monogastrics like humans, swine and poultry, fatty acids from the diet are absorbed as-is by the digestive system. If the diet contains more omega-3 or polyunsaturated fat, there will be more omega-3 or polyunsaturated fat in the animals’ meat or eggs. If the diet contains no trans fats, there will be no trans fat in the meat or eggs.
Modifying the fatty acid composition of meat is more difficult in cattle and other ruminants, because the rumen microbes first break down dietary fats and convert unsaturated fats (like omega-3’s and CLA’s) into saturated fats before the animal absorbs them. This challenge has led to considerable research interest in developing cost-effective feeding strategies to alter the fatty acid composition of beef.
Studies have found that the fat from forage-finished beef contains considerably more CLA and omega-3 than grain-finished beef. However, the majority of Canadian consumers trim the external fat from a steak before eating it, leaving only the marbling fat. Forage-finished beef usually has less marbling fat than grain-finished beef. When CLA and omega-3 levels are calculated on a per-steak basis, the difference between forage- and grain-finished beef virtually vanishes for CLA, although omega-3 levels are still considerably higher in grass-fed than in grain-fed steaks.
Because a nutrient content claim for omega-3 requires at least 300mg per 75g serving of beef, the total omega-3 content of Canadian beef would have to increase by five to eight times to reach the levels required for a nutrient content claim. Under the Beef Science Cluster, National Check-Off funds are supporting a study led by Dr. Ira Mandell at the University of Guelph to identify breed and forage combinations that may increase CLA and omega-3 levels in beef. Results of this study will be available in Summer 2013.
In addition to forage-finishing, another approach has been to feed sunflowers (for CLA) or flaxseed (for omega-3) to increase the dietary supply of the raw materials needed to manufacture these fatty acids in the rumen.
Rumen pH buffer
A third approach is based on the theory that rumen pH influences fatty acid levels in beef. Due to its lower starch content, dried distillers’ grains with solubles (DDGS) can act as a rumen pH buffer when used to replace grain in the finishing diet. A study led by Dr. Mike Dugan at the Lacombe Research Station received National Check-Off funds to examine whether adding a pH buffer (1.5% sodium sequicarbonate or distillers’ grains) to a barley-based diet would affect CLA or omega-3 levels.
Although there has been some progress, neither oilseeds nor buffers have successfully increased omega-3 levels enough to reach a nutrient content claim.
A fourth approach has been to feed fishmeal to cattle. This has been more successful in increasing DHA and EPA omega-3 levels in beef, however, feeding even low amounts of fishmeal to cattle can adversely affect the flavour, colour and shelf life of beef. Much of the flavour of meat comes from the fat. A change in the fatty acid composition that negatively affects the eating quality of beef is unlikely to benefit either beef producers or consumers.
Although it has proven difficult to increase omega-3 levels in beef enough to achieve a nutrient content claim, this research has vastly increased our knowledge of the fatty acid composition of beef. This is very important to ensure that the industry has the information that is needed by consumers, food retailers, and regulators.
To learn more about research on this topic, visit the Functional Fatty Acids page on BeefResearch.ca.
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