The randomized controlled trial (RCT) is the gold standard of medical evidence. Many things that we thought were true because of anecdotal or epidemiologic evidence later turned out to be the opposite of true when studied by RCTs. But RCTs are hard to do. It takes a lot of time and money to properly get a group of study subjects and properly assure they are randomly assorted for everything but the study question. A nifty new way to ensure proper randomization is the natural way of mendelian randomization. Now that we can easily find the genes that are associated statistically with different traits like blood pressure and cholesterol, the rest of a person’s genes are amply randomized in the DNA-making process of reproductive cells. (1)
This cool trick was used in a study reported on this week’s Journal of the American Medical Association that found that a genetically increased waist-to-hip ratio (WHR) (means big belly instead if big hips) which is independent of overall fatness was strongly causative of type-2 diabetes and coronary heart disease. (2) These investigators used gene data from the United Kingdom Biobank on 2 cohorts of 149,821 and 184,305 individuals each.
This and other studies show that overall overweight and obesity as measured by the body mass index (BMI) only causes 11% of heart attacks whereas increased WHR causes 34%. We generally try to fight overall obesity mostly unsuccessfully, but we should really be fighting big abdominal fat, also unsuccessfully so far, but maybe that’s a smaller target. Maybe we can find intermediary steps between those genes and big waists that are possible targets of treatment.
John DiTraglia M.D. is a Pediatrician in Portsmouth. He can be reached by e-mail- firstname.lastname@example.org or phone-354-6605.