Shalene McNeil, PhD, RD, of the National Cattleman’s Beef Association sent out an update on December 15th, 2011. This update discusses a study by Penn State that was just published in the December 2011 American Journal of Clinical Nutrition. One of the key “takeaways” in the Beef Nutrition News article states “By including lean beef daily, study participants in this randomized controlled clinical study experienced a 10% decrease in LDL-cholesterol from baseline." The email concludes with, “This latest study on beef’s role in a heart-healthy diet provides additional science to make evidence-based recommendations.” Such statements about this study might lead some to believe eating more lean beef actually helps lower LDL-cholesterol and could even be heart-healthy.
In fact, a close look at the study reveals that eating more lean beef had nothing to do with the modest drop in LDL-cholesterol levels observed in this study, nor does this short-term study tells us much about whether replacing pork, poultry, and fish with lean beef would impact the risk of developing atherosclerosis and coronary heart disease (CHD).
The AJCN study had 36 subjects between the ages of 30 and 65. All participants had moderately elevated LDL-cholesterol levels. In this study, everyone consumed 4 different diets, for 5 weeks each. All subjects consumed each of the 4 diets in random order with a one week "washout" period between each test diet period. All the foods for each of the 4 diets were provided by the researchers and compliance was carefully monitored. The changes in blood lipids and other variables of the 3 experimental diets were compared to what they called a “Healthy American Diet” (HAD). The HAD contained 33% fat calories and 12% saturated fatty acids and 287mg of cholesterol. The two “beef in an optimal lean diets” (BOLD) and DASH diet all had 5-6% less total fat with only 6% saturated fat and about 100mg less cholesterol than HAD. The 2 BOLD and DASH diet all had more fiber than the HAD as well. The first BOLD was basically a DASH diet but with 3 more ounces of lean beef replacing pork, poultry, and fish. The BOLD+ diet had an additional 1.5oz (or 5.5oz/day) compared to the BOLD. BOLD+ also had much more total protein than HAD, BOLD or DASH from plant sources, nonfat dairy, and egg whites. As a result BOLD+ got 27% of its total calories from protein, compared with 17%, 18%, and 19% in the HAD, DASH, and BOLD, respectively. Also compared to HAD, which provided 24g of fiber/day, the DASH, BOLD, and BOLD+ diets provided 36, 32, and 38g of fiber/day, respectively. By design, all subjects had to remain weight stable throughout the experimental period. What the results showed were quite predictable, given the similar intake of saturated fat and cholesterol coupled with extra fiber on the DASH, BOLD, and BOLD+ diets. Compared to HAD, the DASH, BOLD, and BOLD+ all reduced LDL-cholesterol levels by about 6%. HDL-cholesterol levels fell about as much as LDL-cholesterol levels on all 3 experimental diets and serum triglyceride and other lipoprotein changes were statistically insignificant for the most part. There was some evidence to suggest that the higher protein content in place of refined carbohydrates, while not increasing saturated fat and cholesterol content, when consuming the BOLD+ diet might have had some additional benefits on some components of the inflammation process as seen earlier in the OMNI Heart Trial.
What this study clearly does not show is that replacing omega-3 rich seafood with even the leanest red meat is not heart healthy. Nor does it show that replacing beans, whole grains, fruits, and vegetables with even the leanest beef would not raise LDL-cholesterol levels and promote CHD. Instead, it would promote cardiac issues, since substituting beef for whole plant foods would result in a reduction in fiber intake and an increased intake of saturated fat and cholesterol.
What this Penn State study does show is that if one is willing to consume only the very leanest of beef while still cutting saturated fat and cholesterol intake just as much as on a DASH diet, then short-term impact on blood lipids and other CHD risk factors will not be much different. The authors do state that: “Adhering to the BOLD and BOLD+ diets that we prepared might be challenging for consumers, at least initially, and, therefore, decreases in LDL-cholesterol concentrations would be less than expected.” True, but more importantly this study tells does not negate the growing evidence linking increased red meat intake with an increased risk of CHD, type 2 diabetes, several types of cancer, and other possible ills. Eating more beef and less plant foods would also have clear adverse effects on the environment as well.
By James J. Kenney, PhD, FACN.
For more information go to foodandhealth.com and check out our information on Diet and Heart Disease. You can also get more information at in the October 2011 edition of the Nutrition Action Health Letter.