The combination of an unbalanced diet, including high amounts of sugars and fats, in individuals with a genetic predisposition raises the risk of developing type 2 diabetes by up to 119%.
On the other hand, in people with a high genetic risk of developing diabetes, a balanced diet, with fruits, vegetables and raw vegetables and low consumption of ultra-processed foods, reduced the risk of the disease by 30%.
The results are from the largest study to evaluate genetic factors in conjunction with environmental factors for the determination of diabetes to date. The complete research data were published in the specialized journal PLoS Medicine on Tuesday (26).
The study was conducted by researchers from the United States, institutions such as Harvard University, Sweden (from Lund University) and China (from Dalian Maritime University).
The research analyzed data from 35,759 adults who participated in three cohorts (epidemiology studies with an extended follow-up period) in the US from 1986 to 2017.
The difficulty in past studies of measuring how much of the population risk of developing a disease is caused by the environment and how much is caused by genetics is in the identification of genetic markers and their association with certain diseases.
In the case of the American study, the scientists did an extensive job of mapping all the genes involved in the risk of having diabetes from the large database in the United Kingdom (UK Biobank). With a sample of more than 391,000 individuals, of which 17,403 had diabetes, the researchers identified more than 850,000 gene variants, of which about 893 were associated with the presence of type 2 diabetes.
To evaluate the diet, the Alternate Healthy Eating Index (AHEI) was calculated, which consists of a balanced diet with the base of the food pyramid formed by fruits, vegetables and raw vegetables, whole grains, nuts and other oilseeds. , and a low consumption of ultra-processed products (rich in saturated fats and low in nutrients).
Thus, study participants were divided into low genetic risk (when there was a low frequency of variants associated with the development of diabetes), intermediate and high.
Relative to genetic factors alone, the risk of developing diabetes for these people was 29% higher than for those without the variants. The assessment of diet in conjunction with genetic risk factors had some variations.
For those at low genetic risk, the association of a low-quality diet increased the risk of developing diabetes by 31%; in patients with intermediate genetic risk, this value was 53%; in those who were at high risk, it reached an average of 119%.
The proportion of cases of type 2 diabetes in excess calculated by environmental or genetic factors was 53.3% for hereditary risk, 38.6% for nutrition and only 7.8% for the sum of the two, indicating that the two factors together do not have that much of an effect on whether or not diabetes develops, compared to both separately.
Jordi Merino, a researcher at the Harvard Genomics and Diabetes Center, told Sheet that the study reveals that about a third of the risk of developing type 2 diabetes can be avoided with a balanced diet alone.
“Our research suggests that, even for those at high genetic risk, a healthy diet can reduce that risk by up to 30%. These findings can guide public policy on how to improve consumption of healthier diets, reduce inequalities in access to food and promote information about better food choices.”
Diabetes is a disease caused by high blood glucose (sugar) levels, associated with chronic metabolic inflammation and a reduced ability to produce insulin to reduce these sugar levels. Diabetes cases have increased in Brazil and in the world in the last two years of the pandemic, and, worldwide, almost 7 million people die from causes associated with diabetes each year.
The research, however, has limitations. As the population studied consisted mostly of white people, it cannot be extrapolated to all ethnicities.
“However, the sampling biases due to the population are minimal. The next step would be to conduct a clinical study to evaluate the minimum and maximum genetic risks in more heterogeneous populations”, says Merino.