Grass-fed vs. grain-fed: surprising results
Our recently updated database includes listings for new foods that many of you have been asking about. For example, the USDA now has nutrient information for grass-fed beef and bison. For the past several years, grass-fed meat has been promoted as a healthier alternative to the more typical grain-fed sources. For one thing, it is much leaner.
Livestock get fatter eating corn and other grains than they do eating grass and other greens. (Many would point out that the same is true of humans!) When you compare the new listings for grass-fed bison and regular bison, for example, you'll see that the grain-fed has twice as much fat.
But it has also been widely promoted that meat from grass-fed bison is higher in omega-3 fats and/or lower in omega-6. In fact, the proportion of omega-3s to total fat and to omega-6 fats appears to be virtually the same. An ounce of grass-fed bison has about half as much omega-3 as an ounce of grain-fed bison. (Remember that it also has half as much total fat.) And the ratio of Omega-6 to Omega-3 is about 7:1 for both types. I also detected virtually no difference in other nutrients such as vitamin E, selenium, or zinc.
The differences between grass- and grain-fed beef are slightly more compelling. The listing for grass-fed ground beef contains close to the same amount of fat as 90% lean ground beef. However, the grass-fed contains more omega-3 fats and has a slightly better omega ratio (5:1 for grass-fed versus 7:1 for grain-fed). The total amount of omega-3 fats, however, is fairly small. There are no significant differences in vitamin and mineral content.
For those looking for leaner sources of red meat, grass-fed definitely fits the bill, and is becoming more widely available. I also believe that raising livestock on pastures instead of feed lots is more humane and better for the environment and, for that reason, I go out of my way to choose grass-fed on those rare occasions when I eat meat.
However, if you are looking for a way to increase your intake of omega-3s or other nutrients, you may need to look elsewhere.
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Posted by: Michael | May 10, 2009 9:05:00 AM
My concern is about the so-called "free range" animals. I can imagine they're allowed to roam about at will in non-grassy quarters but they return to soybean or other grain feeders. And just because meats are "vegetarian" or "grain" fed doesn't mean much. Does the producer think a vegetarian will eat "vegetarian-fed" meat? Probably the grain is soybean or corn? This only tells me to avoid such omega 3 low & 6 high meats.
Other than internet sites, healthy pasture or grass fed meats are hard to come by in grocery stores. I see it at Whole Foods, beef at Wegmans, but only misleading "free-range" or "grain fed" at Trader Joe's. Recently I learned that New Zealand lamb is only pasture-fed but check the ranch where it comes from and check that online.
Posted by: ttraynor | Mar 2, 2009 8:16:34 PM
WOW on that last comment. Grass fed/natural meats/healthy food can really taste delicious--better even. I'll take the 6-months of life included with the delicious meats, thank you very much! AND be more vital and robust along the way. Do your strength training and turn that meat into functional muscle!
Posted by: unknown | Mar 2, 2009 10:57:28 AM
dont worry about being healthy! we all die someday. might as well eat what tastes good and REALLY satisfies your taste. its been proven that a "healthy eating" person lives only 6 months longer. that isnt worth eating bad tasting foods for a lifetime. So, might as well eat that GOOD grain fed, fat, tasty beef!
Posted by: Family Nutritionist (http://familynutritionist@blogspot.com) | Jan 15, 2009 2:43:51 PM
Isn't the grass-fed ground beef (http://www.nutritiondata.com/facts/beef-products/10526/2) even more similar to the 85% fat-free ground beef (http://www.nutritiondata.com/facts/beef-products/6198/2)?
Posted by: Robert Brown | Jan 11, 2009 2:57:43 PM
I like Evelyn Tribole would like to see more data on the feed and lifestyle of the bison.
Do these animals get concentrate feed top ups.
What quality of pasture are they on.
I would expect ratios closer to 1:1 than those cited. I will recheck the trials I have seen.
New Zealand lamb has an Omega 3:6 ratio of not far off 1:1.
http://www.nutritiondata.com/facts/lamb-veal-and-game-products/4539/2
In a one ounce serving
Total Omega-3 fatty acids
356
mg
Total Omega-6 fatty acids
437
mg
Robert Brown
Author Omega Six The Devils Fat
www.Omegasixthedevilsfat.com
Posted by: Evelyn Tribole, MS, RD | Jan 9, 2009 8:26:37 PM
Some cattle are fed primarily a corn-grain diet, and then get "finished" on a grass diet just before slaughter. Would these meats be categorized as grass-fed?
The omega-3 fat increases with more days of grazing in the pasture, which also results in a decrease in the proportion of omega-6 to omega-3 fats.*
Also, grazing animals get more activity than those eating the corn-grain feedlot cuisine.
*Noci, F et al.The fatty acid composition of muscle fat and subcutaneous adipose tissue of pasture-fed beef heifers: Influence of the duration of grazing. J Anim Sci 2005 83:1167-1178.
[http://jas.fass.org/cgi/content/full/83/5/1167]
Evelyn Tribole, MS, RD
Author Ultimate Omega-3 Diet
Posted by: Craig W | Jan 8, 2009 1:10:09 PM
Monica cites USDA as the source for the numbers, in the first PP.
Posted by: Dave | Jan 7, 2009 2:27:54 PM
Hmmm, I wonder what they called "grass fed". There's no standardization of that designation, and there's a big difference between 100% pastured beef and those who spend time on feedlots, possibly finished on grass (which in turn may be dried, also a big difference). It is known, for example, that the more time spent in a feedlot, the lower the omega-3 (J Animal Sci (1993) 71(8):2079-88). There is substantial literature backing these conclusions, see e.g. http://www.thepaleodiet.com/newsletter/PDUpdate0407.shtml and references.
What is the source of this data?
Another point: pastured cattle have very low levels of acid-resistant E-coli, the strain that seems to cause various outbreaks. See e.g.
Diez-Gonzalez, F., et al. (1998). "Grain-feeding and the dissemination of acid-resistant Escherichia coli from Cattle." Science 281, 1666-8.
