An Unjustified Knock Against Grass Fed BeefDecember 2nd, 2010
Animals raised in a natural environment and on their natural diet are likely be healthier, and in turn, be a source of higher quality meat. Based on this premise, choosing meat from pasture raised animals makes a lot of sense and is supported by research that has identified a number of ways in which this type of meat is superior. However, a recent study done by researchers from Texas A&M is being used to claim the opposite, that beef from grain fed cattle is healthier than beef from pasture fed cattle.
Although there are many great reasons to choose meat from pasture raised livestock, eating conventionally produced meat is not necessarily a guarantee for poor health. Someone who primarily eats whole foods, is active, and manages stress well will still be likely to enjoy good health despite the concerns associated with conventionally produced meat. However, to insinuate in a general sense that beef from grain fed cattle is healthier than that from pasture fed beef is quite a stretch in my opinion.
Does HDL Cholesterol Define Overall Health?
Unfortunately, the full text of the Texas A&M study hasn’t been published, but the abstract1 provides enough of an overview to understand the basis of the research. 27 men each consumed 3 types of ground beef with each type being consumed exclusively for a 5 week period. The men were split into 3 groups to alter the order of the 5 week periods. One type of ground beef was from pasture fed cattle while the other two were from cattle fed corn for either a short or long duration.
The researchers found a statistically significant correlation between the amount of monounsaturated fat in the ground beef and the participants’ plasma levels of high density lipoproteins (HDL). This is considered to be beneficial because higher levels of HDL, which is often referred to as “good cholesterol,” have been associated with a reduced risk for heart disease. The beef from the cattle fed corn for the longest duration contained the most monounsaturated fat while the beef from the pasture raised cattle contained the least. From this, the researchers concluded that “consumption of high-oleic acid ground beef can increase HDL-C.”1 Fair enough.
Although this conclusion is specific and reasonable, at least based on the information provided by the abstract, the authors made a major and inappropriate projection by stating in the study’s title that “ground beef from corn-fed cattle provides greater health benefits than ground beef from pasture-fed cattle.” The vagueness of “greater health benefits” can easily be misconstrued to mean that beef from grain fed cattle is healthier in general than beef from pasture fed cattle. If you search for articles based on this research, you can see that this is exactly what happened. In fact, there’s even an article about the study on the Texas A&M website titled “Study shows ground beef from grain-fed cattle healthier than grass-fed.”2
HDL is only one of many factors associated with heart disease, and it’s not even one of the more important ones.96 Furthermore, although heart disease is the leading cause of death in the United States,3 it’s only one of many conditions that result in poor health and compromised quality of life. As such, I consider it inappropriate to use improved HDL levels as the justification for implying that beef from grain fed cattle is better for overall health. Besides, the Texas A&M researchers failed to acknowledge a number of other differences between the two types of meat that are arguably much more important.
Balance of Essential Fatty Acids
It’s estimated that the relative intakes of the omega-3 and omega-6 essential fatty acids throughout human evolution were roughly equivalent. However, due to changes in agricultural methods and an increase in the use of vegetable oils, we now consume as much as 20 times more omega-6 fatty acids than omega-3 fatty acids. Essential fatty acids have many important physiological roles, and because the human body cannot produce them, we must obtain them through diet. However, the imbalanced intake that is now common has been shown to be a significant concern due to its association with heart disease, cancer, asthma, arthritis, and mental illness.4-10
Research has shown that meat from pasture raised animals tends to have a much more favorable ratio of omega-6 to omega-3 fatty acids than meat from grain fed animals.11-14 In one case, the ratio in meat from grain fed animals was shown to be nearly 5 times greater.14 In this regard, meat from grain fed animals presents more of a risk for heart disease and other serious health concerns.
Vulnerability to Lipid Oxidation
Polyunsaturated fatty acids, including the omega-6 and omega-3 essential fatty acids, are very susceptible to oxidation.15-17 The oxidation of these fatty acids produces free radicals that are damaging to cells and are associated with a number of health concerns including heart disease, stroke, cancer, arthritis, asthma, and accelerated aging.18-23 They’re believed to cause damage to the endothelial cells that line arteries and induce the lesions associated with atherosclerosis.24,25 Low density lipprotens (LDL), which are often given the misleading designation of “bad cholesterol,” contain these easily oxidized polyunsaturated fatty acids. When they’re oxidized, the LDL molecules that contain them are referred to as “oxidized LDL.” Although it’s somewhat questionable to refer to LDL in general as “bad cholesterol,” oxidized LDL in particular is believed to be a significant cause of artery damage and increase the risk of atherosclerosis.26-30
Unfortunately, the polyunsaturated fat in food can become oxidized when exposed to oxygen, light, or the high temperatures of cooking,15-17,22,23,31 and the consumption of this oxidized fat has been shown to increase the concentration of oxidized LDL in the blood.32,33 The fat in meat from grain fed animals has been shown to be more susceptible to oxidation than the fat in meat from pasture fed animals.13,34 This is believed to be a result of meat from grain fed animals containing less vitamin E13,34 which is known to protect against the oxidation of fatty acids.17,22,35,36 Based on this, meat from grain fed livestock poses a greater risk of increasing oxidized LDL levels, and in turn, increasing the risk of atherosclerosis.
Even if polyunsaturated fatty acids are not oxidized when consumed, an excessive intake increases the polyunsaturated content of LDL molecules which makes the LDL more susceptible to oxidation.37-39 Although the meat from grain fed animals tends to contain an unfavorable ratio of omega-6 to omega-3 fatty acids, it doesn’t necessarily contain more polyunsaturated fatty acids in general. However, this less desirable ratio could encourage one to consume more omega-3 fatty acids, and in turn, consume more polyunsaturated fatty acids overall.
In regard to the results of the Texas A&M study, one of the benefits of HDL is that it protects against LDL oxidation.26,29,40,41 However, the improved HDL levels observed by the researchers are negated and of little value if the meat that promotes this improvement also increases the risk of LDL oxidation and its harmful effects.
Hormones, Antibiotics, and Pesticides
Despite being fed an unnatural diet, some grain fed livestock are raised with great care and may only be fed such a diet for a brief period. However, it’s more likely for the meat commonly found in grocery stores to be of poorer quality and come from animals raised under the questionable conditions of factory farms. These animals may be given hormones to accelerate or increase their growth, and they may be exposed to pesticide residues and mold toxins from being fed low quality feed. Because such conditions are likely to impair their health, they may also be given antibiotics on a regular basis to reduce the incidence of illness.
This is a moral dilemma to say the least, but the focus of this discussion is nutritional quality. Research has shown that the residues of pesticides, hormones, and antibiotics that conventionally raised livestock are commonly exposed to can be found in their meat.42,97-99 This presents a number of health concerns and is obviously not synonymous with a high level of quality.
Misrepresentation of Trans Fat
There’s little doubt that trans fat is unhealthy and increases the risk for heart disease. However, this is a generalization that applies to the trans fat that’s artificially derived from vegetable oils. During this process, which is referred to as hydrogenation, hydrogen atoms are added to unsaturated fatty acids to give them the more solid and stable properties of saturated fatty acids.43
Although the harmful nature of the trans fat found in hydrogenated vegetable oils has become common knowledge, not as many people realize that there are natural forms of trans fat that exist in the meat and milk of ruminant animals.44 However, it’s important to realize that these trans fats differ in structure than those derived from vegetable oils. Elaidic acid is the primary trans fat found in hydrogenated vegetable oils while trans-vaccenic acid is the primary trans fat found in ruminant animals. Although these two fatty acids are isomers of each other, which means that they share the same chemical formula, they have different structures based on a double bond being located in different positions.45 Although this might sound trivial, it’s not uncommon for such a seemingly small difference in molecular structure to have a significant impact.
Although both of these fatty acids are technically trans fatty acids, only one of them is deserving of the negative connotation associated with trans fat. Research has shown that it’s the elaidic acid in hydrogenated vegetable oils that’s associated with an increased risk of heart disease, not the trans-vaccenic acid naturally found in the meat and milk of ruminant animals.45-47 In addition, the meat and milk of ruminants also contain another type of trans fat called conjugated linoleic acid (CLA) which is believed to have many health benefits including the potential to reduce body fat, increase lean body mass, protect against cancer, heart disease, and diabetes, and enhance immune function and bone development.11,48-51 Trans-vaccenic acid, the dominant trans fatty acid in animal fat, is believed to be a precursor to CLA in both animals and humans, and consumption of trans-vaccenic acid has been shown to increase levels of CLA.52
Beef from pasture fed animals tends to contain more trans-vaccenic acid and CLA than animals fed grain.12,53 Based on the potential benefits of CLA and the evidence of trans-vaccenic acid not being harmful, this can be regarded as a benefit. However, one of the Texas A&M researchers seems to have put a negative and misleading spin on the issue as if there’s no difference between these natural trans fatty acids and the trans fat artificially derived from vegetable oils. On the university’s own website, he’s quoted as saying that “as we talked to some user groups and told them that we had found pasture-fed beef is higher in saturated [and] trans-fat, they were shocked.”2 (I added [and] to the quote assuming a transcription mistake based on the fact that there’s no such thing as a “saturated trans fat.” The existence of such a fat is contradictory by definition and isn’t even possible.)
Good Science or Just Clever Language?
Most people are probably not aware of the differences between trans fat from ruminant animals and hydrogenated vegetable oils, and if not, they’re certainly not aware of the different health implications. Based on this, they’re likely to assume that all trans fats are bad and interpret “shocked” as a negative response. I truly hope that this statement about trans fat wasn’t made with malicious intent, but either way, the potential for it to be misleading is still the same.
Along with the projection of improved HDL levels defining overall health, this is an unfortunate example of how subtle language choices made by researchers can encourage information to be misconstrued by the media. Good science relies on seeking truth and presenting it clearly to minimize the potential for misinterpretation. Unfortunately, it seems to me that this research is lacking these qualities.
A Side Note About Saturated Fat
Although I don’t consider the difference in saturated fat content to be an important comparison between the meat from pasture fed and grain fed animals, I feel obligated to acknowledge it since it’s mentioned in the quote about trans fat that I referenced.
Some research confirms that beef from pasture fed cattle contains more saturated fat,14 but other research has shown it to contain less.53 Either way, this is only relevant if you believe that saturated fat is inherently unhealthy. Despite the popularity of the belief that it’s harmful and is a significant risk factor for heart disease, there is quite a bit of convincing support indicating that saturated fat is misunderstood.54-66,96 In fact, it’s essential for important aspects of health. Saturated fat is a component of adipose tissue,67-69 and as such, contributes to energy storage and thermal insulation.70 Its concentration has been found to be higher in visceral fat which indicates its importance in protecting and supporting vital organs.69 It’s also essential for proper function of cell membranes,71-73 the brain and nervous system,74,75 and even the lungs.76-78 In addition, saturated fat contributes to the resiliency of skin,79,84-87 can enhance immunity,79-83 and has ironically been shown to be a significant if not dominant source of energy for the heart.88-92
Saturated fat also relates to the previous discussion about oxidized LDL. Research has shown the blood concentration of oxidized LDL to increase after after consuming a supposedly healthy diet that decreases saturated fat and overall fat intake while increasing polyunsaturated fat intake.93
A Different Outlook on What’s “Healthy”
Improved HDL levels are generally a byproduct of living a truly healthy lifestyle with the intent of promoting optimal health. For example, exercising is an important part of maintaining and promoting good health, and it has also been shown to improve HDL levels.94,95
One of the Texas A&M researchers claimed that “we looked at the scientific literature and could not find any justifications for the statement that pasture-fed beef is better for you.”2 I won’t make any assumptions about why they didn’t find any of the research that I referenced in this article, but the point remains that it exists, isn’t difficult to find, and in my opinion provides plenty of justification.
Because of the multitude of factors that can influence health, making healthy decisions requires a broad perspective. The Texas A&M researchers found that ground beef from grain fed cattle improves HDL levels, and from this very narrow and focused perspective concluded that meat from grain fed cattle is healthier than meat from pasture fed cattle. However, with a broader perspective that considers essential fatty acid imbalance, susceptibility to oxidation, and the existence of chemical residues, it seems to me that it’s their statement that isn’t justified.
If anything, the Texas A&M study supports the benefit of consuming monounsaturated fatty acids. However, if you want to increase your intake of this type of fat, you’d be better off eating avocados than eating meat from an animal not fed its natural diet.
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