More grains, less meat key to preventing type 2 diabetes

Meat is linked to an increased risk for type 2 diabetes (T2D), and it may be due to higher levels of obesity-related inflammatory biomarkers. The good news is that reducing meat-based protein consumption and replacing it with plant-based proteins substantially reduces the risk. Indeed, substituting 5% of dietary energy from plant protein for 5% of energy from animal protein was associated with a 21% reduced risk of T2D, according to a study investigating dietary protein and T2D risk. Results were published in Diabetes Care. “We found that intake of animal protein sources from red meat, processed meat, poultry, or eggs was directly associated with increased T2D risk, while plant protein sources from whole grains or nuts were associated with decreased risk,” the researchers wrote. Read: Not always healthy: what your patients need to know about plant-based diets Looking at dietary proteins was of interest because accumulating evidence show that red meat, processed meat and eggs may increase T2D risk, whereas whole grains and dairy products may decrease risk. To do the study, researchers used data from two long-term population studies: the Women’s Health Initiative (WHI) and the U.K. Biobank. The WHI cohort included older postmenopausal women in the U.S. and the U.K. Biobank (UKB) included both adult men and women who were younger than the WHI population. The UKB was used for a replication analysis. “We used the U.K. Biobank along with the WHI to observe if we could see the consistency of findings across these cohorts (and so) findings could be more generalizable to the targeted source populations,” said study coauthor Dr. Simin Liu, a professor of epidemiology, surgery and medicine at Brown University in Providence, RI. The study’s goals were to investigate the roles of different animal and plant protein sources in relation to incident T2D among participants in the two population studies and examine whether T2D-related biomarkers could explain the association of substituting plant protein for animal protein in case-control studies that were nested in the WHI. The WHI cohort included 108,681 postmenopausal women (mean age of 63 years at baseline who were enrolled between 1993 and 1998). Women with diabetes at enrolment were excluded. Of these, 15,842 (14.6%) developed T2D during a median follow-up period of 15.8 years. The UKB data included 14,902 men and 19,714 women who were followed for a median of 11.4 years, of whom 663 developed incident T2D cases. For the WHI, dietary data were collected at enrollment and at other points. A total of 12 dietary protein sources were taken into account for the current study. It was found that greater daily average intake of red meat, processed meat, poultry, eggs, and low–Omega-3 seafood was associated with increased T2D risk, while greater intake of whole grains and nuts was inversely associated with lower likelihood of developing T2D. But there was a spectrum of risk, with red and processed meat showing the highest risk or T2D development, and poultry, eggs and low-Omega-3 seafoods showing the next highest risk. Grains and nuts had the lowest risk. Regular consumption of high Omega-3 seafood, cheese, milk, yogurt, and legumes had little to no association with T2D risk, the study found. The highest consumers of animal protein eaters were eating, on average, 66.6 grams per day or about 2.3 ounces, whereas, those in the lowest group were consuming on average, 40.0 grams per day in the WHI or about 1.4 ounces, Dr. Liu said. Replacing one serving per day of red meat, processed meat, eggs, or poultry with protein sources from whole grains, lead to a 13 to 26% decreased risk of T2D. The findings were consistent in the UKB cohort. “It is possible that people who eat more plant protein have an overall healthier lifestyle. However, even when we take into account these known lifestyle practices, those who consume more plant protein appeared to be independently associated with better outcomes,” Dr Liu told the Medical Post. The researchers adjusted for BMI, race, physical activity, alcohol, family income, multivitamin use, and overall diet to help account for any lifestyle differences. A subset of the WHI population had blood work done at different points in the study making it possible to look at the presence of inflammatory biomarkers. The study included 1,445 incident T2D cases and 2,019 control subjects. When compared to the control subjects, the T2D subjects had higher BMI, waist circumference, HOMA of insulin resistance, inflammation factors, endothelial dysfunction markers, leptin, and had lower sex hormone-binding globulin (SHBG). These markers are known to be associated with T2D risk, and the measures were higher those who ate more red meat. Dr. Liu noted that animal protein has more saturated fat, dietary cholesterol, and heme iron, and less fibre and polyphenols than plant source, which may be why improvements are seen in cardiometabolic diseases and risk factors when substituting plant protein for animal protein sources. “Family doctors can recognize the benefits of replacing some animal protein sources with plant protein sources in their patients’ diets, particularly among those at risk of developing type 2 diabetes (but because) family doctors are busy they should consider referring them to registered dietitians for nutrition counseling,” he said. The findings are not surprising, according to Dr. David Jenkins, a physician and professor of nutrition sciences at the University of Toronto. He was not involved in the study. Meat consumption is associated with increased risk for diabetes, cardiovascular disease and some types of cancer for a variety of reasons, he said. One reason is that meat consumption, especially eating too much, may lead to too much heme iron which could add to diabetes and other health issue risks. Plant proteins have fewer potential inflammatory factors, he said.

More grains, less meat key to preventing type 2 diabetes

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