The systematic review – published in the American Journal of Clinical Nutrition – pools together data from previous clinical trials investigating the effects of trans-fats in the diet in order to better assess whether consumption of the fat is linked to the development of diabetes.
“Although evidence from cohort studies has suggested that trans-fatty acid (TFA) consumption may be associated with insulin resistance and diabetes, randomised placebo-controlled trials (RCTs) have yielded conflicting results,” explain the researchers, led by Dr Christos Mantzoros of Harvard Medical School, USA.
After analysing data from more than 200 people in seven clinical studies, Mantzoros and his team reveal that although TFA consumption is linked to increases in ‘bad’ cholesterol, consumption does not appear to have lasting impacts on blood sugar or insulin resistance.
“Increased TFA intake does not result in changes in glucose, insulin, or triglyceride concentrations but leads to an increase in total and LDL-cholesterol and a decrease in HDL-cholesterol concentrations,” write the researchers, adding that “there is no evidence to support a potential benefit of the reduction of dietary TFA intake on glucose homeostasis.”
The link between TFA consumption and high cholesterol is widely accepted; however some studies have also linked high consumption to an increased risk of heart disease, and diabetes. This has led to pushed for the reduction – and in some cases complete removal – of the substance from processed foods.
In order to get a better sense of trans-fats' influence on blood sugar and insulin, Mantzoros and his team pooled the results from seven previous clinical studies including data from 208 people.
The primary outcomes of these studies were glucose and insulin concentrations, while secondary outcomes were total, LDL-, and HDL-cholesterol and triglyceride concentrations.
Mantzoros and his colleagues reveal that increased TFA intake does not result in significant changes in glucose or insulin concentrations. However, higher intake did lead to a significant increase in total and LDL-cholesterol levels, in addition to a significant decrease in HDL-cholesterol (‘good’ cholesterol) levels.
Source: American Journal of Clinical Nutrition
Volume 96, Number 5, November 2012, Pages 1093-1099, doi: 10.3945/ajcn.112.040576
“Effects of trans fatty acids on glucose homeostasis: a meta-analysis of randomized, placebo-controlled clinical trials”
Authors: Konstantinos N Aronis, Sami M Khan, Christos S Mantzoros