During the study, which was led by scientists at the Children's Hospital Oakland Research Institute (CHORI), more than 100 healthy men and women between the ages of 21 and 65 were randomly assigned to consume either red meat, white meat or nonmeat protein diets for four weeks.
All participants cycled through all three diets, with each diet lasting four weeks. For a period of two to seven weeks between each round, participants were told to eat their usual diets. Participants on the red meat diet mostly ate beef as their protein source, while the participants on the white meat diet mostly ate chicken. People on the no meat diet consumed foods like vegetables, dairy, legumes and beans. Researchers took blood samples from all participants before and at the end of each diet cycle.
Many dieticians claim that saturated fats, found in animal sources such as beef fat, butter and even poultry skin, increase the concentration of LDL in the body. LDL stands for low-density lipoproteins and is often dubbed "bad cholesterol." Even though cholesterol is a waxy substance made by your liver and found in your cells, having too much of the substance in your body can cause it to accumulate in your arteries, increasing your risk of coronary heart disease.
The study found that white and red meat affected the participants' cholesterol levels equally, while plant proteins were found to be the healthiest for blood cholesterol. A diet in high saturated fat was found to increase "bad cholesterol" regardless of the protein source.
"When we planned this study, we expected red meat to have a more adverse effect on blood cholesterol levels than white meat, but we were surprised that this was not the case — their effects on cholesterol are identical when saturated fat levels are equivalent," multiple reports quoted the study's senior author Dr. Ronald Krauss, senior scientist and director of Atherosclerosis Research at CHORI, as saying.
"Our results indicate that current advice to restrict red meat and not white meat should not be based only on their effects on blood cholesterol," Krauss added. "Indeed, other effects of red meat consumption could contribute to heart disease, and these effects should be explored in more detail in an effort to improve health."
Researchers also found that small and large bad cholesterol particles both contribute to atherosclerosis in both the red meat and white meat diets, the build-up of fats and cholesterol in and on artery walls, despite the belief that small particles may contribute more to the hardening of arteries than large ones. The study did find, however, that a high saturated fat diets in general were associated with larger LDL particles.