The popular Paleo diet is based on eating foods thought to be available to our ancestors during the Paleolithic era, before the advent of dairy or processed grains. Findings from a small study suggest that people who followed the Paleo diet for only eight weeks experienced positive effects on heart health. Preliminary findings from this research will be presented at the American Physiological Society's Inflammation, Immunity and Cardiovascular Disease conference.
"Very few studies have examined the Paleo diet in seemingly healthy participants, despite the prevalence of this dietary practice in health and fitness enthusiasts," said study author Chad Dolan, a graduate student researcher at University of Houston Laboratory of Integrative Physiology.
The researchers asked eight healthy people who normally consumed a traditional Western diet high in processed foods to switch to the Paleo diet -- which consists of minimally processed foods -- for eight weeks. The participants received a sample Paleo diet menu and recipe guide, as well as initial counseling on how to incorporate the Paleo diet into their everyday lives. They were told to eat as much food as they wanted while following the diet.
The researchers found that the study participants experienced a 35 percent increase in levels of interlukin-10 (IL-10), a signaling molecule secreted by immune cells. A low IL-10 value can predict increased heart attack risk in people who also have high levels of inflammation. Scientist think that high IL-10 levels may counteract inflammation, providing a protective effect for blood vessels.
Although the researchers have not yet analyzed inflammation levels in the study participants, the increase in IL-10 could suggest a lower risk for cardiovascular disease after following the Paleo diet. The researchers also observed changes in other biomarkers of inflammation, but further investigation is needed to understand whether these changes indicate increased inflammation or a protective mechanism at work.
Even though the study was not designed to promote weight loss, the participants did drop some pounds during the eight-week trial. Compared with what they regularly ate before the study, participants reported consuming around 22 percent fewer calories and 44 percent fewer grams of carbohydrates on the Paleo diet.
This preliminary feasibility study did not include a control group of people not following the diet, making it difficult to determine if the changes observed in inflammation biomarkers resulted from specific food choices, reduced calories, fewer carbohydrates or weight loss.
"This study's findings add to the possibility that short-term dietary changes from a traditional Western pattern of eating to foods promoted in the Paleo diet may improve health -- or, at the very least, the diet does not have negative health implications in terms of the parameters we studied," Dolan said. "If our research continues to show that the Paleo diet produces detectable changes in healthy individuals, it will substantiate claims made by those supporting this diet for the past few decades and provide preliminary evidence for another therapeutic strategy for cardiovascular disease and coronary artery disease prevention."
The researchers caution that the current findings are both preliminary and incomplete in this group of participants. They plan to conduct a study with a greater number of people who follow the diet for a longer period of time to analyze how it affects various risk factors for cardiovascular and coronary artery disease, cellular immune function and metabolic health.
The study was a collaborative effort between the Human Performance Laboratory at Chatham University in Pittsburgh and the University of Houston Laboratory of Integrative Physiology.
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