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Do you know the difference between grass-fed and grass-finished meats? Maybe it's because I've eaten a plant-based diet for the last 8 years, but I don't remember ever hearing the term "grass-finished" throughout naturopathic medical school. Shouldn't the terms be interchangeable? Unfortunately, they are not...
Grass-fed versus Grass-finished: what's the difference?
The terminology of "grass-fed" meat implies that the animal ate grass. It doesn't explain any length in time or the conditions that the animal ate grass, just that they ate it at some point. In fact, most cows in Canada are started on a grass-based diet. However, at some point these animals are often introduced to grains, either supplementary or a full grain-based diet, which allows them to quickly gain weight before being slaughtered. Additionally, "grass-fed" does not imply "pasture raised" or any other claims in regards to their living conditions.
According to the Canadian Food Inspection Agency (CFIA), it is up to the farm or company to provide accurate claims on their labels that are not misleading to the public. Currently, there are no regulations to guide such claims and no standardization of the term "grass-fed" or how long an animal was fed grass to be allowed to use that label.
In comparison, "grass-finished" meat is from animals that ate a grass-based diet for the entirety of their lives. Meaning they weren't introduced to grains at any point. More to come on why that is important. It wasn't until recently when I decided to start reintroducing a small amount of meat into my diet, that I was introduced to the idea of grass-finished meat by my amazing farmer Stacey (Coghlan Cottage Farm). After learning the difference, I thought it was important to research into the regulations and the implications of animal feed on the nutrient profiles of their meat. And here we are!
So, why does it matter?
Previously, I touched on the idea that grain is used as feed to help promote quick growth of an animal, especially their fat content. Grain-fed meat often has a marbled appearance because the grain increases the intramuscular fat content. It gives the meat a tender texture and a different taste. Some would argue that its more desirable meat for these reasons; there's no doubt that fat content makes foods taste good!
I want to be clear that fat isn't the enemy. We need fat in our diet as a longterm energy source and to build cell membranes, hormones, vitamin D, bile, and more! Certain fats can't be made by the body and therefore must come from our diet; these are referred to as essential fatty acids (EFAs). The EFAs are known as linoleic acid (an omega-6 fatty acid) and linolenic acid (an omega-3 fatty acid). From these two molecules the body can make other necessary fatty acids and molecules by using a series of enzymes. However, these two different families compete for the same enzymes, which means the balance between the two is extremely important. Omega-6 fatty acids are converted into predominantly pro-inflammatory molecules, whereas omega-3 fatty acids are converted into anti-inflammatory molecules. Here's a simplified diagram for my visual learners:
Studies have shown that Western diets have a very high omega-6 to omega-3 ratio; approximately 11 to 30 times more omega-6. This imbalance has been shown to increase the risk of heart disease, arthritis, depression, cancer, and other inflammatory diseases. The current recommendation of a balanced omega-6 to omega-3 ratio is 1-4:1. Not only does a more balanced ratio prevent some inflammatory conditions, omega-3 fatty acids can also be used to treat inflammatory conditions including eczema, psoriasis, post-concussive syndrome, endometriosis, IBD, and many more!
While studies have shown that grass-finished meat has a lower total fat content, the clinical importance is that grass-finished meat has a better overall fatty acid profile. Not only is it higher in omega-3 fatty acids, but it has a more favourable omega-6 to omega-3 ratio compared to grain-fed meat. "In fact, as the concentration of grain is increased in the grass-based diet, the concentration of omega-3 fatty acids decreases in a linear fashion" (1). Similarly, the level of trans fat increased linearly with an increased length of time that the animals were fed a grain-based diet (7). Dietary trans fat has been correlated to many conditions including heart disease, liver disease, obesity, and infertility.
Additionally, the linoleic acid in grass-finished meat translates to having approximately 2-3 times higher conjugated linoleic acid (CLA) content due to how grass effects stomach acidity in ruminant animals compared to grain-fed animals (2,3). CLA has been shown to reduce the risk of cancer, heart disease, and onset of diabetes. Other than the favourable fatty acid profile in grass-finished meat, it is also higher in beta-carotene (a precursor to Vitamin A), and Vitamin E; both of which are fat-soluble vitamins and have anti-oxidant effects in the body.
The take home points:
There is a difference in the nutrient content between grain-fed, grass-fed, and grass-finished meat; this includes higher levels of omega-3 fatty acids, CLA, beta-carotene, and Vitamin E.
There is a linear increase in the amount of these nutrients the longer an animal is fed grass. Furthermore, there is a lower amount of trans fat, the longer an animal is fed grass.
Grass-fed doesn't equal grass-finished, and there is no guideline for how long an animal has to eat grass in order to be labelled as "grass-fed". They may have been started on grass and transitioned to grains after a few months old.
Therefore, it's important to look into the claims your meat makes on the package, or better yet, find a local farmer where you are confident in the quality of meat you are buying. Not only can it improve your health, the animals are typically treated more ethically, and it is better for the environment!
References:
Daley, C. A., Abbott, A., Doyle, P. S., Nader, G. A., & Larson, S. (2010). A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutrition Journal, 9(1). doi: 10.1186/1475-2891-9-10
Duckett SK, Wagner DG, Yates LD, Dolezal HG, May SG: Effects of time on feed on beef nutrient composition. Journal Animal Science. 1993, 71: 2079-88.
French P, Stanton C, Lawless F, O'Riordan EG, Monahan FJ, Caffery PJ, Moloney AP: Fatty acid composition, including conjugated linoleic acid of intramuscular fat from steers offered grazed grass, grass silage or concentrate-based diets. Journal Animal Science. 2000, 78: 2849-55.
Gaby, A. (2017). Nutritional medicine. Concord, NH: Fritz Perlberg Publishing.
Government of Canada / Gouvernement du Canada. (2019, March 8). Retrieved from https://www.inspection.gc.ca/food-label-requirements/labelling/industry/method-of-production-claims/eng/1389379565794/1389380926083?chap=8#s4c8.
Marmer WN, Maxwell RJ, Williams JE: Effects of dietary regimen and tissue site on bovine fatty acid profiles. Journal Animal Science. 1984, 59: 109-21.
Ponnampalam, E. N., Mann, N. J., & Sinclair, A. J. (2066). Effect of feeding systems on omega-3 fatty acids, conjugated linoleic acid and trans fatty acids in Australian beef cuts: potential impact on human health. Asia Pac J Clin Nutr, 15(1).
Whitney, E. N. (2012). Understanding nutrition. Toronto: Nelson Education.
Wood JD, Enser M: Factors influencing fatty acids in meat and the role of antioxidants in improving meat quality. British Journal of Nutrition. 1997, 78: S49-S60. 10.1079/BJN19970134.