Is Grass-Fed Beef Healthier than Conventional?
We often hear of the nutritional benefits of grass-fed and grass-finished beef when compared to conventional beef. But what does the data actually say? Read on for my review of the latest science.
Unpopular conclusion: barely.
This is a topic that will ruffle some feathers, but we need to be honest with ourselves when making decisions about what we eat. The short answer is that there simply isn’t a lot of data suggesting that grass-fed beef is healthier than conventional grain-fed beef.
While we do see quite dramatic differences in eggs from pasture-raised poultry, dairy from grass-fed cattle, and wild-caught seafood, we just don’t see these same differences in grass-fed steak compared to feedlot-finished beef in the scientific literature.
In the largest study to date, researchers from Michigan State University analyzed the nutritional content of 750 samples of commercially available grass-fed beef loin from 12 producers across 10 states in the U.S. The beef was supplied by farms raising as little as 25 head of cattle, to farms raising as many as 5,000 head.
The total fat content of the beef varied widely, from 0.08–3.6 grams per 100 grams of beef, with an average of 0.7 grams. Comparatively, a conventional beef loin steak trimmed of all fat contains 5.6 grams of fat per 100 grams of beef. There were also notable variety in the concentrations of all tested individual fatty acids. You can see the differences between grass-fed and conventional beef fat composition in the table below.
There is a lot that can be said about the differences in fat composition, but some key focus points are as follows:
Grass-fed beef is leaner.
Both have a similar concentration of saturated fat (45% of total fat).
The omega-6 to omega-3 ratio is far lower in grass-fed beef.
Conventional beef provides more CLA.
Of the four major points above, the only one of real merit is that grass-fed beef is leaner. That 5-gram difference in total fat content translates to 45 Calories per 100 grams of beef, which can easily add up for someone eating a lot of beef and who has a low energy requirement. Still, one could just opt for leaner cuts of conventional beef, such as eye of round which has 2.5 grams of fat per 100 grams of beef.
I know many of you may point towards the lower omega-6 to omega-3 ratio as evidence of superiority, but look at the absolute amounts. If you eat a kilogram of beef (2.2 pounds), then you are still getting only 3.2 grams of omega-6 fatty acids in conventional beef. That’s 3 times less than supplied by an ounce of walnuts and roughly equivalent to an ounce of almonds.
Same deal with the omega-3 content. A kilogram of grass-fed beef provides only 35 mg of EPA and 3 mg of DHA, with most of its omega-3 content being alpha-linoleic acid. One need only eat about 3 grams of chinook salmon to obtain the same amount of EPA and DHA; a 100-gram fillet provides roughly 1 gram of each. And we may as well ignore the ALA since it is not readily converted into the long-chain omega-3 fatty acids associated with health benefits: EPA and DHA.
That said, swapping out 690 grams per week (about 24 ounces or 1.5 pounds) of red meat from conventional cattle for red meat from grass-fed cattle and lamb has been shown to significantly increase serum concentrations of total omega-3 fatty acids, including DHA, and reduce the serum omega-6 to omega-3 ratio. Daily intake of DHA was shown to increase by 4.5 mg from 9.5 to 14 mg, which is in-line with the values of DHA found in grass-fed beef. However, given the wide variation in the omega-3 content of commercially available grass-fed beef samples, you have no way of knowing whether eating grass-fed beef would have the same impact on you. Plus, participant screening excluded anyone who ate oily fish more than twice a month. Would eating grass-fed beef be of any note if one ate even just one serving of oily fish every week? We need to look at how a food will impact the person’s entire week of meals, not one bite.
Same deal with the CLA content. In one randomized controlled trial, having adults supplement their diet with 2.2–2.7 grams of CLA per day for several weeks had no significant effects on health markers other than a marginal reduction in triglycerides. To obtain this level of CLA intake would require eating 10–12 kg (22–27 lbs) of conventional beef and an equivalent amount of grass-fed beef if we use the maximum recorded CLA content (23 mg per 100 grams of beef).
Now, many of these differences are probably quite appreciable when using isolated tallow, since it is pure fat. However, when opting for beef, especially lean beef, there isn’t that big of a difference between grass-fed and conventional cattle. So, when folks report that grass-finished beef has more omega-3 or CLA or whatever, we need some context for that statement. Three pennies are more than one penny, but it’s still not a lot of money!
The Michigan State University study also looked at concentrations of minerals and antioxidants. Again, there was wide variation in many of these compounds, including iron, zinc, copper, selenium, vitamin E, and β-carotene. On average, amounts of most were higher than conventional beef, but not to an appreciable extent. The differences amounted to roughly 1 mg iron, 13 mg magnesium, 200 mg potassium, 20 mcg copper, and 0.4 mg of vitamin E.
In short, there are differences between grass-fed and conventional beef, with grass-fed being more nutritionally dense. However, the differences are small and of little real-world significance, especially considering that eating other foods can easily overshadow any contributions from the beef.
But what about other non-nutrient constituents like pathogenic bacteria and toxicants?
According to the Centers for Disease Control (CDC), in 2017, food poisoning outbreaks were most often caused by mollusks (19%), fish (17%), chicken (11%), and beef (9%). For beef, the issue stems largely from E. coli O157:H7, which often makes it way into beef through contamination with fecal matter. Yet, fecal samples of grass-fed and conventional cattle show similar concentrations of E. coli. However, this ignores the production methods of retail beef. Consumer Reports found that E. coli and other pathogenic bacteria were more prevalent on commercial cuts of conventional beef than grass-fed beef, likely due to how the cattle are slaughtered and brought to market (e.g., meat and fat coming from multiple animals and slaughter rates of a couple hundred head per hour). Plus, the bacteria on conventional cattle demonstrate a greater resistance to common antibiotics, meaning that any food poisoning has a chance of being more severe. Of course, this entire issue is circumvented by simply cooking your meat enough, but that runs into other problems with palatability and the formation of carcinogens from cooking meat harshly (e.g., “well-done” or grilling).
As for toxicants, many persistent organic pollutants are lipid-soluble and stored in the fat of animals, including humans. It makes sense that cattle which are exposed to higher levels of environmental pollutants and pesticides on their feed would contain more toxicants in their meat. However, beef from cattle who eat feed grown with glyphosate show the same negligible concentrations of glyphosate as beef from cattle who never ate glyphosate. Glyphosate in the feed of cattle doesn’t even appear to negatively impact their body composition or metabolic health. Certainly, there exists a risk that other toxicants do present in greater concentrations in beef from conventional cattle, but we don’t have any evidence of this.
Another area where we don’t have much research is on the effects of stress, particularly the stress occurring soon before slaughter, on the nutritional quality of meat. We’ve known since at least the 70s that stress within 48 hours of slaughter causes glucocorticoids to infiltrate the meat and lower its pH (makes it more acidic) and make the meat less tender. However, whether slaughter stress or chronic stress from the factory farm environment impacts the nutritional content of beef hasn’t been investigated.
We wish that a better nutritional case for grass-fed beef could be made, but the available evidence indicates that differences between it and conventional beef are minimal and largely confined to the fat content. Before you throw out this post, this doesn’t mean that we are arguing against buying grass-fed meat. We certainly need more research on this topic. We may learn that the type of forage cattle are finished on is key, or that other compounds like polyphenols play an important role. We hope to learn more soon. There are certainly many other very good reasons to eat grass-finished beef, as we’ll explain in the environmental and ethics sections, but nutrition (from the peer-reviewed evidence we have to date), really isn’t one of them.
This is where the “less meat, better meat” ideology can be problematic. Given that many people don’t have access to grass-fed and -finished beef; given the benefits of eating more protein, especially from animal products like beef; and given that grass-fed and conventional beef have minimal nutritional differences; folks should simply buy the best meat they can afford. A steak from feedlot-finished beef is still more nutritious than rice and beans. If we are to solve our growing obesity and diabetes issues, plus provide nourishment to those who are food insecure and need better nutrition, the message of “less meat” is not going to help.
