Cardiovascular disease and type 2 diabetes in evolutionary perspective: a critical role for helminths
Heart disease and type 2 diabetes are commonly believed to be rare among contemporary subsistence-level human populations, and by extension prehistoric populations. Although some caveats remain, evidence shows these diseases to be unusual among well-studied hunter-gatherers and other subsistence populations with minimal access to healthcare. Here we expand on a relatively new proposal for why these and other populations may not show major signs of these diseases. Chronic infections, especially helminths, may offer protection against heart disease and diabetes through direct and indirect pathways. As part of a strategy to insure their own survival and reproduction, helminths exert multiple cardio-protective effects on their host through their effects on immune function and blood lipid metabolism. Helminths consume blood lipids and glucose, alter lipid metabolism, and modulate immune function towards Th-2 polarization - which combined can lower blood cholesterol, reduce obesity, increase insulin sensitivity, decrease atheroma progression, and reduce likelihood of atherosclerotic plaque rupture. Traditional cardiometabolic risk factors, coupled with the mismatch between our evolved immune systems and modern, hygienic environments may interact in complex ways. In this review, we survey existing studies in the non-human animal and human literature, highlight unresolved questions and suggest future directions to explore the role of helminths in the etiology of cardio-metabolic disease.
Department of Anthropology, University of California-Santa Barbara, Santa Barbara, CA 93106 gurven@anth.ucsb.edu. School of Human Evolution and Social Change & Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85287. Institute for Advanced Study in Toulouse, 21 allée de Brienne, 31015 Toulouse Cedex 6, France. Department of Anthropology, University of California-Santa Barbara, Santa Barbara, CA 93106. University of California, Irvine School of Medicine; Depts of Pediatrics and Infectious Diseases. Andrus Gerontology Center and Dept. Neurobiology USC College, University of Southern California, Los Angeles, CA 90089. Department of Anthropology, University of New Mexico, Albuquerque, NM 87131.
