Column #162 September 28, 2018
There are many more differences between grass-fed and grain-fed beef than just their balances of Omega-6 (n6) to Omega-3 (n3) essential fatty acids (EFAs). In 2010, Cynthia A. Daley and her team of researchers examined some of the differences in a review study based on 30 years of research. It’s titled: “A Review of Fatty Acid Profiles and Antioxidant Content in Grass-Fed and Grain-Fed Beef.”
The goals of the review were to investigate the nutrient claims for grass-fed beef and discuss the effects these specific nutrients have on human health.
A medley of quotes from their report tells the story.
● Red meat, regardless of feeding regimen, is nutrient dense and regarded as an important source of essential amino acids, vitamins A, B6, B12, D, E, and minerals, including iron, zinc and selenium.
● Regardless of the genetic makeup, gender, age, species or geographic location, direct contrasts between grass and grain rations consistently demonstrate significant differences in the overall fatty acid profile and antioxidant content found in the lipid depots and body tissues.
● Pasture raised beef is lower in overall fat, particularly with respect to marbling.
● Grass-fed beef consistently shows higher concentrations of n-3 FAs as compared to grain-fed contemporaries, creating a more favorable n-6:n-3 ratio. There are a number of studies that report positive effects of improved n-3 intake on CVD and other health related issues.
● Data in the review studies shows significant differences in n-6:n-3 ratios with an overall average of 1.53 and 7.65 for grass-fed and grain-fed, respectively.
● Grass-based diets have been shown to enhance total conjugated linoleic acid (CLA a.k.a C18:2) isomers, trans vaccenic acid (TVA a.k.a. C18:1 t11), a precursor to CLA, and n-3 FAs on a g/g fat basis.
● Several studies suggest that grass-based diets elevate precursors for Vitamin A and E, as well as cancer fighting antioxidants such as glutathione (GT) and superoxide dismutase (SOD) activity as compared to grain-fed contemporaries.
● Over the past two decades numerous studies have shown significant health benefits attributable to the actions of CLA, as demonstrated by experimental animal models, including actions to reduce carcinogenesis, atherosclerosis, and onset of diabetes.
● Grass-fed beef has a distinct grass flavor and unique cooking qualities that should be considered when making the transition from grain-fed beef. In addition, the fat from grass-finished beef may have a yellowish appearance from the elevated carotenoid content (precursor to Vitamin A).
● Although yellow carcass fat is negatively regarded in many countries around the world, it is also associated with a healthier fatty acid profile and a higher antioxidant content.
● Plant species, harvest methods, and season significantly impact the carotenoid content of forage. In the process of making silage, haylage or hay, as much as 80% of the carotenoid content is destroyed.
● Carotenes (mainly beta-carotene) are precursors of retinol (Vitamin A), a critical fat-soluble vitamin that is important for normal vision, bone growth, reproduction, cell division, and cell differentiation. Specifically, it is responsible for maintaining the surface lining of the eyes and also the lining of the respiratory, urinary, and intestinal tracts.
● Pasture-fed steers incorporated significantly higher amounts of beta-carotene into muscle tissues as compared to grain-fed animals. Concentrations were 0.45 μg/g and 0.06 μg/g for beef from pasture and grain-fed cattle respectively, demonstrating a 7-fold increase in b-carotene levels for grass-fed beef over the grain-fed contemporaries.
● Grass only diets improve the oxidative enzyme concentration in beef, protecting the muscle lipids against oxidation as well as providing the beef consumer with an additional source of antioxidant compounds.
● Antioxidants such as vitamin E protect cells against the effects of free radicals. Free radicals are potentially damaging by-products of metabolism that may contribute to the development of chronic diseases such as cancer and cardiovascular disease.
● The concentration of natural a-tocopherol (vitamin E) found in grain-fed beef ranged between 0.75 to 2.92 μg/g of muscle whereas pasture-fed beef ranges from 2.1 to 7.73 μg/g of tissue depending on the type of forage made available to the animals. Grass finishing increases a-tocopherol levels three-fold over grain-fed beef
● Glutathione (GT), is a relatively new protein identified in foods. Within the cell, GT has the capability of quenching free radicals (like hydrogen peroxide), thus protecting the cell from oxidized lipids or proteins and prevent damage to DNA. GT and its associated enzymes are found in virtually all plant and animal tissue and is readily absorbed in the small intestine.
Here are some of the antioxidants in beef:
6. Vitamin A
7. Vitamin C
8. Vitamin E
The biochemistry of grass-fed beef differs from grain-fed in its aroma and flavor. Because of its lower lipid content and high concentration of PUFAs, cooking times are less.
Since people prefer the foods they grew up eating, the transition from grain-fed to grass-fed beef usually requires some adjustment. Acquiring new taste preferences requires repetition which can mean eating it as many as 15 times before the taste is acquired.
These differences between grain-fed beef and grass-fed beef illustrate what happens to animal bodies when their diets deviate from having the green leaf at the bottom of the food chain. The same thing happens to humans. When people eat a lot of grains, seeds, nuts, fruit, and grain-fed animal products (meat, eggs, dairy) compared to grass-fed/Omega-3 meats, wild-caught seafood, and green leafy vegetables they too will experience a variety of nutritional deficiencies and excesses. These deviations from the grass-based norm lead to various body failings that come under the heading of chronic diseases.
Interestingly, many important nutrients such as n-3 EFA, CLA, beta carotene, vitamins E and A are two to seven times higher in grass-fed over grain-fed beef. Being grass-fed certainly has it’s advantages. That’s why this comparative study underscores my emphasis on the importance of complete foods which have the nutrient diversity and density of dark green leafy vegetables such as kale, spinach, and broccoli. These foods are also low glycemic with close to 1:1 EFA balances. Deviations in the diet from these fundamentally complete foods only dilutes the nutrients a body requires for proper function. Therefore we can rest assured that over time our bodies will respond accordingly to what we decide to eat.
To your health.
Ted Slanker has been reporting on the fundamentals of nutritional research in publications, television and radio appearances, and at conferences since 1999. He condenses complex studies into the basics required for health and well-being. His eBook, The Real Diet of Man, is available online.
Don’t miss these links for additional reading:
A Review of Fatty Acid Profiles and Antioxidant Content in Grass-fed and Grain-fed Beef by Cynthia A Daley et al.
Antioxidants: Beyond the Hype from Harvard T.H. Chan School of Public Health
Key Nutrients Delivered by Red Meat in the Diet by Peter Williams