I’m aware that a lot of readers here do not eat meat, either for religious reasons (Buddhist), ethical reasons (animals are more sentient than we are taught), or environmental reasons (traditional meat raising damages the environment in many ways). Still, I eat meat, and sometimes (about once a week or less), I eat beef – grass fed beef.
A new study reveals the health benefits of grass-fed beef that many of us already knew about, but which has not yet permeated mainstream culture. Nutrition Journal (an open source publisher) recently posted A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef, a study by Cynthia A Daley, Amber Abbott, Patrick S Doyle, Glenn A Nader. and Stephanie Larson. Here is the abstract:
Nutrition Journal 2010, 9:10doi:10.1186/1475-2891-9-10
|Published:||10 March 2010|
Growing consumer interest in grass-fed beef products has raised a number of questions with regard to the perceived differences in nutritional quality between grass-fed and grain-fed cattle. Research spanning three decades suggests that grass-based diets can significantly improve the fatty acid (FA) composition and antioxidant content of beef, albeit with variable impacts on overall palatability. Grass-based diets have been shown to enhance total conjugated linoleic acid (CLA) (C18:2) isomers, trans vaccenic acid (TVA) (C18:1 t11), a precursor to CLA, and omega-3 (n-3) FAs on a g/g fat basis. While the overall concentration of total SFAs is not different between feeding regimens, grass-finished beef tends toward a higher proportion of cholesterol neutral stearic FA (C18:0), and less cholesterol-elevating SFAs such as myristic (C14:0) and palmitic (C16:0) FAs. 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. Fat conscious consumers will also prefer the overall lower fat content of a grass-fed beef product. However, consumers should be aware that the differences in FA content will also give grass-fed beef 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). It is also noted that grain-fed beef consumers may achieve similar intakes of both n-3 and CLA through the consumption of higher fat grain-fed portions.
If you don’t speak science-geek, this may not mean much to you, so let me break it down a bit, into info you can use.
First, let’s look at saturated fat content. In traditional feedlot beef, the saturated fat levels are quite high, and there is considerable evidence that an imbalance of dietary cholesterol and fats are the primary cause of atherosclerosis and cardiovascular disease (CVD) . Grass-fed beef is higher in tends to be healthier in this respect.
Here is a summary of the fat content of grain-fed beef (traditional beef):
animal fats contribute approximately 60% of the SFA in the American diet, most of which are palmitic acid (C16:0) and stearic acid (C18:0). Stearic acid has been shown to have no net impact on serum cholesterol concentrations in humans[17,19]. In addition, 30% of the FA content in conventionally produced beef is composed of oleic acid (C18:1) , a monounsaturated FA (MUFA) that elicits a cholesterol-lowering effect among other healthful attributes including a reduced risk of stroke and a significant decrease in both systolic and diastolic blood pressure in susceptible populations .
Based on this summary, even traditional beef seems less the health scourge that so many claim it is. However, the real issue is in the saturated fatty acids (SFA):
For instance, lauric acid (C12:0) and myristic acid (C14:0), have a greater total cholesterol raising effect than palmitic acid (C16:0), whereas stearic acid (C18:0) has a neutral effect on the concentration of total serum cholesterol, including no apparent impact on either LDL or HDL. Lauric acid increases total serum cholesterol, although it also decreases the ratio of total cholesterol:HDL because of a preferential increase in HDL cholesterol [5,7,9].
Grass fed beef is higher in stearic acid, which has no real effect on serum cholesterol levels. Grain fed beef is higher in lauric acid, palmitic acid, and myristic acid, the more harmful fatty acids associated with heart disease and high cholesterol levels raising the risk for heart attack and stroke. Further, the study reports on research by Garcia et al (2008), showing that grass fed beef contains 40.3 of cholesterol/100 grams of tissue and grain fed beef contains 45.8 grams of cholesterol/100 grams of tissue, not a huge difference, but statistically important.
However, in terms of oleac acid, an omega-9 fatty acid associated with reductions in heart disease risk, grain fed beef does better, sort of.
Interestingly, grain-fed beef consistently produces higher concentrations of MUFAs as compared to grass-fed beef, which include FAs such as oleic acid (C18:1 cis-9), the primary MUFA in beef. A number of epidemiological studies comparing disease rates in different countries have suggested an inverse association between MUFA intake and mortality rates to CVD [3,21]. Even so, grass-fed beef provides a higher concentration of TVA (C18:1 t11), an important MUFA for de novo synthesis of conjugated linoleic acid (CLA: C18:2 c-9, t-11), a potent anti-carcinogen that is synthesized within the body tissues .
This is where the differences in health outcomes may become most obvious. CLA is gaining more and more attention for its health benefits (from being anti-cancer to helping with weight loss). There are many isomers of CLA, and it remains unclear which ones are the most beneficial, although the “cis-9, trans-11 CLA isomer,” which accounts for up to 80-90% of the total CLA in grain fed beef, is one of the most studied and beneficial isomers.
The authors of this study point out that dietary intake of CLA should consider “native 9c11t-C18:2 (actual CLA) as well as the 11t-C18:1 (potential CLA) content of foods,” because the human body can convert this potential CLA, known as TVA, to CLA at a rate of 19 to 30% . The highest levels of CLA c9t11 and TVA in meat is generated through a diet high in grasses and “lush green forages.”
Here is a section from the study on the health benefits of CLA:
Optimal dietary intake remains to be established for CLA. It has been hypothesized that 95 mg CLA/day is enough to show positive effects in the reduction of breast cancer in women utilizing epidemiological data linking increased milk consumption with reduced breast cancer. Ha et al. (1989) published a much more conservative estimate stating that 3 g/day CLA is required to promote human health benefits. Ritzenthaler et al(2001) estimated CLA intakes of 620 mg/day for men and 441 mg/day for women are necessary for cancer prevention. Obviously, all these values represent rough estimates and are mainly based on extrapolated animal data. What is clear is that we as a population do not consume enough CLA in our diets to have a significant impact on cancer prevention or suppression. Reports indicate that Americans consume between 150 to 200 mg/day, Germans consumer slightly more between 300 to 400 mg/day, and the Australians seem to be closer to the optimum concentration at 500 to 1000 mg/day according to Parodi (1994) .
There is obviously no agreement on how much CLA we need, but the consensus is that we do get enough in the American diet.
Grass fed beef tends to be higher in pro-Vitamin A/β-carotene, which is a powerful antioxidant. This may change the color of the fat, making it more yellowish, which is one way to differentiate grass fed from grain fed beef.
Grass fed beef is also higher in the antioxidant vitamin E. It turns out that this is a good thing for us, as one of the things that vitamin E can do is prevent omega-3 fats from becoming rancid. Grass fed beef is much higher is omega-s fats than grain fed beef.
In fact, the ratio of omega-3 fatty acids to omega-6 fatty acids in grass fed beef is 1:2, which is the ideal ratio for the human diet (this is also true of eggs and meat from chicken raised on grass fed diets). The current American diet is generally 1:10 at best to 1:30 at worst in the omega-3:omega-6 ratio. This imbalance in the diet has been associated with a range of health issues, from high cholesterol, risk of stroke, cancer, ADHD, depression, and even autism. We need more omega-3 fats, and grass fed beef is a good source.
Finally, grass fed beef is high in Glutathione (GT), an antioxidant produced naturally in the liver, but also available from food sources. Research in this area is new, but we know that “dairy products, eggs, apples, beans, and rice contain very little GT (< 3.3 mg/100g).” However, “fresh vegetables (e.g., asparagus 28.3 mg/100g) and freshly cooked meats, such as ham and beef (23.3 mg/100g and 17.5 mg/100g, respectively), are high in GT “.
Because GT compounds are elevated in lush green forages, grass-fed beef is particularly high in GT as compared to grain-fed contemporaries. Descalzo et al. (2007) reported a significant increase in GT molar concentrations in grass-fed beef .
So the take away knowledge here is this:
1. While grass fed and grain fed beefs have comparable levels of saturated fat, the SFA in grain fed beef are associated his health risks that are not present in grass fed beef.
2. Grass fed beef is much higher in CLA and TVA (a CLA precursor) than is grain fed beef, and CLA has been associated with body composition changes for the better and decreased risk of various cancers.
3. Grass fed beef is much higher in antioxidants, including vitamin A precursors, vitamin E, and glutathione.
4. Grass fed beef has the optimal 2:1 ratio of omega-3 to omega-6 fats that we need in the human diet.
So if you eat meat, and if you like beef, make sure you are eating grass fed beef. It’s healthier, it’s more organic, and it’s more sustainable. But try to limit your consumption to once a week (or less) – even if it’s more sustainable, it’s a land intensive way to produce our food.
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