This association was confirmed by a new study published in the American Journal of Clinical Nutrition, a data analysis of nearly 217,000 people who were monitored for three decades as part of several cohort studies. “Our study supports the current dietary recommendations of limiting consumption of red meat and highlights the importance of different alternative sources of protein in preventing type 2 diabetes,” the researchers wrote.
Consumption and risk
The study included men and women who took part in the Nurses’ Health Study, the Nurses’ Health Study II, or the Health Professionals Follow-up Study. Questionnaires were used to collect data every 2-4 years on the frequency of specific food consumption. Information on the onset of diseases and on different health-related aspects was collected every 2 years.
Those who consumed more red meat had a higher body mass index, higher total energy intake, and greater likelihood of being a smoker. They were physically less active and less likely to take multivitamins. In a follow-up of 5.48 million person-years, 22,761 cases of type 2 diabetes were recorded.
The link between consumption of processed and unprocessed red meat (and both combined) and a higher risk of diabetes was observed in all cohorts when analyzed separately and jointly. The people in the highest quintile for combined red meat consumption had a 2% greater risk of developing the disease, compared with those in the lowest quintile. The risk increases associated with processed and unprocessed meat were 51% and 40%, respectively. One additional serving per day of processed red meat was associated with a 1.46-fold greater risk of diabetes. This risk was 1.24 times greater for unprocessed meat and 1.28 times greater for both types combined.
The associations had a linear dose-response relationship and remained firm even after accounting for BMI, which the researchers stressed could be a mediating factor. Finally, the associations were stronger when considering the average cumulative consumption over the 30-year follow-up period and still stronger following the calibration of meat consumption with data extrapolated from food registers. The latter step was taken to account for measurement errors.
Alternatives are better
By analyzing alternative protein sources, the researchers discovered that nuts and legumes are associated with the most substantial reductions in diabetes risk. “This discovery is consistent with the evidence that shows that sources of unsaturated fatty acids and antioxidants have beneficial effects on glycemic control, insulin response, and inflammation,” they wrote. By replacing a serving of processed red meat, unprocessed red meat, or a combination of the two with a serving of dry fruit or legumes, the risk of developing diabetes is lowered by 30%, 41%, and 29%, respectively. Replacing red meat with a serving of dairy products is also associated with a reduced risk.
Confirmation
Several biological mechanisms could contribute to the increased risk for type 2 diabetes in people who consume red meat. The high level of saturated fats or the relatively low level of polyunsaturated fats, heme iron, or the high nitrate content in processed red meats could play a role. A strong positive association between consumption of this meat, particularly when processed, and the onset of diabetes has already emerged from other studies, including a trial carried out several years ago in the same cohorts. “In the current study, we wanted to look at this association in the same three cohorts in more detail, with over 9,000 additional cases of type 2 diabetes documented with extensive follow-up,” the researchers explained.
This article was translated from Univadis Italy. A version appeared on Medscape.com.