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Monday Musings: New Grass-Fed Study

Posted By Mark Sisson On January 3, 2011 @ 9:00 am In Big Moo,Fat,Protein | 68 Comments

A new grass-fed meat study [7] (PDF) has just been brought to my attention, thanks to Aaron Blaisdell [8]. It’s pretty fascinating. Researchers wanted to see two things: whether eating grass-finished animals instead of grain-finished animals would provide a significant influx of dietary omega-3s and whether the potential influx would actually make a difference in lab numbers. They took two groups of people, regular Irish folks, and provided weekly portions of beef and lamb, either grass-finished or grain-finished. The animals were “finished” for a minimum of six weeks. Both groups were told to avoid fatty fish [9] and omega-3-rich oils for the duration of the study. All told, both groups ate roughly 469 grams of red meat a week for four weeks. Oh, and these were all healthy subjects with good cholesterol and blood pressure numbers and without prescriptions to any medications.

The results were impressive. Grass-finished eaters saw improved plasma and platelet fatty acid composition: less omega-6, more omega-3. This would presumably lead to a more balanced inflammatory response and, thus, better health.

A few takeaways:

1. The weeks leading up until slaughter appear to be the most crucial feeding period. Although the study’s authors don’t explicitly state what the animals’ pre-trial diets were, the cows and lambs were drawn from a region where the standard feed concentrate included “cereal, maize, and soya with a vitamin/mineral mix” and I think we can assume that both grass-finished and concentrate-finished animals shared the same diets before the trial. Whether those pre-trial diets were grass or grain-based isn’t clear. It is clear that grass-finishing is the key – at least enough to positively impact the omega-6:omega-3 ratios of whoever consumes the animals. Grass-fed and finished is probably optimal, but perhaps not absolutely necessary.

2. It’s interesting, but not really that surprising, that the intervention didn’t affect lipid numbers [10]. LDL, HDL, and triglycerides remained pretty much the same across both groups. The heaviest impact was felt in the serum and platelet fatty acid content. Grass-finished animal eaters enjoyed higher levels of stearic acid (a type of saturated fat [11]), EPA, DPA, DHA, long chain omega-3s, and total omega-3s, along with a reduced omega-6:omega-3 ratio. As we know from previous posts [12], the omega-6:omega-3 ratio of our fat cells determines what type of inflammatory cytokines will be secreted by platelets in the inflammatory response, and having too much omega-6 in our platelets results in a lopsided, overly inflammatory response.

3. If you look at the raw numbers, there’s not a huge difference between the omega-3 content of grass-finished and grain-finished, something on the order of mere mgs/100g. Beef and lamb, even the grass-finished stuff, just doesn’t have a whole lot of omega-3s to begin with. The folks consuming grass-finished meat ate, on average, 65 mg/d of long chain omega-3s, while those eating concentrate-finished meat ate about 44 mg/d of long chain omega-6s, yet the lab results – the big improvements in plasma and platelet fatty acid numbers – were lopsided. What’s the deal? This makes me wonder whether simply breaking food down into its various nutrients and fatty acids is missing the point. If you relied on that, you’d think grain-fed beef was essentially identical to grass-fed, but it’s clearly not, as the results of this study show. Maybe it’s the DPA, an often-ignored omega-3 fat that’s prominent in seal blubber and converts more readily to DHA, and that was increased in the grass-finished group. Maybe, and probably more likely, it’s the fact that omega-6 intake, especially linoleic acid [13] (arachidonic acid [14] intake was actually higher in grass-finished), was significantly higher in the grain-fed group than in the grass-finished group, about 8.5 g/day to 5.5 g/day. Or maybe it’s the fact that grass-finished animal flesh is a complex whole food that offers more benefits than can heretofore be identified and explained.

4. Oily fish is undoubtedly the most concentrated, most reliable source of long chain omega-3 fats in the diet, but you can’t live off fish forever. At least, I can’t. If I have fish more than a few times a week, I become physically repulsed by the thought of eating more. A three day stint of eating almost nothing but fresh sardines taught me that. That’s why I try to always eat grass-fed, grass-finished animals – because, the idea goes, when you’re eating grass-fed ruminants and avoiding concentrated sources of omega-6, you don’t need to supplement or worry about a steady fish intake. This study confirms it.

5. Grass-finished beef steak and mince samples actually had more saturated fat than grain-finished samples. The opposite was true for lamb, however.

All in all, this is just another reason to work grass-fed [15] and (especially) finished animals into your diet whenever possible.


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[7] study: http://cdn.marksdailyapple.com/wordpress/wp-content/uploads/2010/12/McAfeeGrassfedbeefbettern3thanconventionalbeefBJN2011-2.pdf

[8] Aaron Blaisdell: http://pigeonrat.psych.ucla.edu/

[9] fatty fish: http://www.marksdailyapple.com/omega-3-fatty-acid/

[10] lipid numbers: http://www.marksdailyapple.com/blood-test-markers/

[11] saturated fat: http://www.marksdailyapple.com/saturated-fat-healthy/

[12] previous posts: http://www.marksdailyapple.com/fish-oil-health-benefits/

[13] linoleic acid: http://www.marksdailyapple.com/nuts-omega-6-fats/

[14] arachidonic acid: http://www.marksdailyapple.com/arachidonic-acid/

[15] work grass-fed: http://www.marksdailyapple.com/where-to-buy-grass-fed-beef/

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