What should we eat? It seems like the experts" dietary advice is always changing, thanks to the incremental nature of scientific progress. But the latest results, in both nutritional research and animal-science research, provide lots of good news for the beef industry.
What"s not news is that beef is an excellent source of high-quality protein of course, that"s been known for some time or that it contains all the essential amino acids, while most plant proteins lack at least one. And beef also brings many other important nutrients to the plate: iron, zinc, B vitamins, choline. "It"s a nutrient-dense food relative to its caloric value," says Penny Kris-Etherton, a distinguished professor of nutrition at Penn State University. Nevertheless, many doctors and nutritionists in recent decades have advised cutting back on beef because of concerns about its saturated fat content.
Here"s the news that may start to turn that around. First, some researchers are starting to question whether saturated fat is really the culprit driving obesity and heart disease. We"re also finding out that lean beef doesn"t actually contain that much saturated fat: A 3.5-ounce serving of lean beef only has 4.5 grams of saturated fat. (On a 2000-calorie diet, the daily recommendation for saturated fat is 13 grams.) Finally, new animal-science research is showing that there are approaches (genetic choices, feeding regimens) producers can use to change the nutritional profile of beef, making its future even healthier.
Changing view of saturated fat
The saturated fat research story has become very complicated in recent years. It"s been vilified for decades, but now its reputation may be undergoing a rehabilitation. Research published last March in the journal Annals of Internal Medicine did not find that people who ate higher levels of saturated fat had more heart disease than those who ate less. The lead author of the study, Rajiv Chowdhury, a cardiovascular epidemiologist at Cambridge University, told the New York Times, "My take on this would be that it"s not saturated fat that we should worry about." A few months later, on June 23, 2014, Time magazine ran a cover story titled "Eat Butter," which argued that saturated fat is not really the enemy carbohydrates and sugar are.
Scientists understand that the early saturated fat literature evolved from population-based research, which has many limitations. "If you go back in the literature and look at how these recommendations were made, there wasn"t a lot of science there," says Susan Duckett, Ernest L. Corley Jr. Trustees Endowed Chair in the Department of Animal and Veterinary Sciences at Clemson University. "Some of the first studies were basically correlations between what people said they ate and their blood cholesterol levels. They were from different countries, with differences in lifestyle and smoking habits. Now they"ve figured out it"s more complicated than that: Simply eliminating saturated fat from your diet is not going to eliminate the problem."
But this is not to say that we can eat unlimited saturated fat, and some criticize the latest studies. "The research that is coming out now is from epidemiological studies, which cannot tell cause and effect," Kris-Etherton says. Only controlled clinical trials can say a relationship is causal, she says, and controlled clinical studies have shown that saturated fat increases LDL cholesterol (the bad kind). She points to the most recent dietary guidelines, which came out in November 2013 from the American Heart Association and American College of Cardiology. They recommend that saturated fat be decreased to decrease LDL cholesterol. "No government or health organizations are saying don"t worry about saturated fat anymore," she says.
What the scientific community can agree upon, she says, is that when saturated fats are replaced with polyunsaturated fats, there are health benefits. "But when refined carbs are substituted for saturated fat, it"s just a wash," she says. "Low-fat diets are not going to be of benefit."
While researchers continue to work out questions around fats which are certainly complicated by the fact that there are many unique fatty acids within the saturated/unsaturated categories, and they may not all have the same properties what we can say is that lean beef does not actually contain very high levels of the saturated kind. "With intramuscular fat, about half is saturated fat," says Raluca Mateescu, associate professor of quantitative genetics and genomics at the University of Florida. "The other half is mostly monounsaturated, with about 5 percent polyunsaturated fat." Those monounsaturated and polyunsaturated fats are the same kind found in olive oil, avocados and fish and have well-documented positive effects on human health. "Of the saturated half, about 30 percent is stearic acid, which is neutral, so it doesn"t really change the level of bad cholesterol. So you really have very little of the bad saturated fat," she says.
Most experts still agree that a lot of fat any kind is not good for you, she adds. "But a lot of the nutritional recommendations now are saying lean beef is really great because you have a lot of protein, you"ve got all the minerals and vitamins, and you"ve got just a little bit of fat, and that"s not bad," she says. "As humans, we do need fat in our systems."
Lean beef benefits
In her studies, Kris-Etherton has found even more reasons to eat lean beef. She was a lead researcher for a study funded by the Beef Checkoff and the National Institutes of Health-supported Penn State General Clinical Research Center, published in the June 19, 2014, issue of Journal of Human Hypertension. She found that a heart-healthy diet could include lean beef and actually have a beneficial effect on the two major risk factors for heart disease: high cholesterol and high blood pressure.
This diet, which the researchers called BOLD+ (beef in an optimum lean diet) included 5.4 ounces of lean beef a day in a heart-healthy diet that was low in saturated fat (6 percent of calories). Their first study showed that this diet elicited a cholesterol-lowering effect. In a more recent study, they showed the BOLD+ diet caused decreases in blood pressure compared with the average American diet.
The diet had other advantages as well. "Beef brings to the diet a lot of nutrients you"re not going to get from a lot of plant proteins," she says. "Beyond that, being able to include it helps people follow heart-healthy guidelines. When people are told to avoid beef, they have a hard time following dietary recommendations. Showing them how to incorporate it into a healthy diet will really help people adhere to current dietary guidelines, rather than telling them to cut it out of their diet completely."
Change the feed; change the fat
Duckett is among the animal scientists researching ways to make beef even leaner. Her recent project evaluated the impact of different production systems on the meat"s fatty acid composition: feeding grass versus grain, as well as the timing of different feeding regimens. "We typically found that the fat content of the meat would be lower in those finished on grass, usually 40 to 50 percent lower," she says. "It becomes very comparable to other protein sources like chicken in terms of fat content."
She found another benefit of the grass-finished beef: increased levels of the desirable omega 3 fatty acids. "There was a lower ratio of omega 6 to omega 3. Typically health professionals want that to be 4:1 or less," she says. "Grassfed beef is about 1.5:1. Grain fed is about 5:1."
Duckett also experimented with changing the timing of feeding regimens starting some on grass and some on grain and then switching to see how such changes would affect fat levels in the beef. What she found was those that went into the feedlot early and then finished on forage developed the optimum levels of fat. "It appears that early exposure to grain feeding helped to stimulate marbling deposition," she says. "And then by finishing them on pasture we could get a very acceptable product. The ratio of omega 6 to omega 3 was about 2:1. We got the best of both worlds with 100 days in the feedlot and then about 200 days on pasture."
Change the genetics; change the fat
Are genetics another route to change the composition of nutrient levels in beef? That possibility inspired a research project at the University of Florida, Iowa State University and University of California-Davis, in which researchers asked: How much natural variation is there in the fatty acid and mineral composition of beef? If there is natural variation, how much of it is due to genetics? Can we identify the genetic mechanism which is controlling these traits? The answers they found: quite a bit, a moderate amount and yes.
"Of course, the goal is to develop tools we can use to select for more nutritious beef but also tasty beef. We do not want to change that," says Mateescu, who worked on the project and presented the results of the research at this year"s Beef Improvement Federation convention. "If we could have genomic-enhanced EPDs for selecting for favorable fatty acid profile, lower saturated fat, higher concentrations of minerals and vitamins that"s what we are looking for." Mateescu and the team have already succeeded in identifying genomic regions for many of the healthfulness traits they looked at, and these may start showing up on EPD charts one day. "We can use the markers we have for a selection program right now," she says.
All three researchers agree there are strong arguments today for keeping beef on the plate. "If you take lean beef out of your diet, you"re taking a lot of other things out too," Mateescu says. "If it"s lean, it"s really beneficial for you." Duckett hopes the latest research will help spread that news. "I think some of these things are helping to give beef a more positive message," she says. "We need to educate consumers and the medical field about the positives."
Read more, including articles on beef quality and safety, in the September digital edition of Drovers/CattleNetwork.