You probably have heard that grass-fed beef and dairy are ‘better’ their conventional counterparts but may be a little confused as to why. Animal rights are certainly one excellent reason to pick grass-fed (pastured) meats and that’s all well and good but ‘what’s in it for me?’ you ask...
Nutrition science deals with numbers upon numbers and in my degree we were given official looking charts detailing the ‘nutritional value’ of common foods like milk, beefsteak and butter. We were never once asked to consider whether a grass-fed New Zealand Angus steak might differ from a feedlot produced, corn fattened Maine-Anjou steer from the US of A. In undergraduate nutrition: a cow is a cow, is a cow. I have found that some of the best data on nutritional consequences of different livestock feeding regimes is hidden in obscure agricultural science journals.
If grass-fed beef and dairy are better for us then why are the vast majority of our bovine friends fed corn, barley, soy and other grains? North America boasts an impressive excess supply of grains and soybeans. Grain-fed cows grow faster, produce a higher carcass weight (more profit per head of cattle per unit time for the farmer) and are more likely to meet Canadian grade A standards for beef. Beef is graded on marbling, colour and taste and grain feeding produces a whiter fat, more marbling and a more ‘acceptable’ taste to the consumer. The higher the beef grade, the higher price a farmer can charge for his hard work. When you add in antibiotics and growth hormones it is no surprise that the Canadian Beef inc. boasts of achieving a 53% increase in average meat yield per cow between 1972 and 2008. This is all sounding pretty good for the farmer right? But what about for you, the consumer?
Omega 3:6 ratio
The Western diet typically has an overabundance of omega 6 fatty acids due to our large intake of seed oils and relatively low seafood intake. Omega 6 and omega 3 fatty acids compete for the same metabolic pathways that manufacture cell signalling molecules, modulators of gene expression and inflammation. The products of omega 3s tend to be anti-inflammatory while those of omega 6s tend to be pro-inflammatory. One of the aims of the paleo diet is to bring down our omega 6 intake and increase our omega 3 intake to improve our metabolic health.
Grass-fed beef has an average omega 6:3 ratio of ~1.53 whereas grain-fed beef has an average of ~7.65. This huge difference is because, like humans, cows incorporate the fats from their diet into their tissues. Corn and soy are rich in omega 6 fats while grass fats are largely omega 3s.
While eating more fatty fish and avoiding refined seed oils will have a bigger impact on your dietary omega 3 and 6 intake, if you do eat conventional grain fed meat it is prudent to choose the leanest cuts available to further minimize your omega 6 intake.
Micronutrients and antioxidant compounds
If you closely inspect a grass-fed meat cut you may notice a yellowy tinge to the fat. The yellow colour come from carotenoids, vitamin A precursors derived from grass. Grass-fed beef is higher in carotenoids (~8x higher) and vitamin E. These micronutrients are abundant in grass but not so in the diets of feedlot cows. Together with higher concentration of the antioxidant compounds glutathione and superoxide dismutase, these nutrients help to keep grass-fed meat fresh for longer (antioxidants fight oxidative damage not only in your body but in the meat itself after the cow is butchered) and provide you, the consumer with a more nutritious meat.
Conjugated Linoleic Acid (CLA)
CLAs are a group of trans fatty acids found in very tiny amounts in the human diet. These recently discovered fats that have been shown experimentally to reduce body fat, inhibit cancer growth and reduce heart disease risk. CLA research is going gangbusters recently and you can even buy CLA supplements at your local gym junkie haven (the drug store). While these supplements can induce weight loss they also can interfere with blood sugar regulation and increase oxidative stress. Supplementation may even increase breast cancer risk. Natural sources of CLA haven’t been shown to induce these negative effects so it’s best for now to stick to meat and airy for your CLA intake.
Bacteria in the cow rumen produce CLA from fats in the cow’s diet. Grass-fed animals have a less acidic rumen environment which helps bacteria to form CLA, in fact, grass fed cows have 4-6 times more CLA in their meat and milk than grain fed cows. In summer, grass fed dairy has the highest levels of CLA as this is when cows have access to the most grass.
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