A new study suggests that diets high in polyunsaturated omega fats may increase the risk of developing type 2 diabetes.
Type 2 diabetes is a chronic condition in which the body is unable to use insulin properly, leading to difficulties regulating blood sugar levels. Although genetic factors can play a role in onset of the illness, it is estimated that over 80% of cases could be prevented through management of lifestyle factors such as diet and exercise.
While dietary modifications to prevent type 2 diabetes tend to focus on carbohydrate consumption, there is some indication that fats, which constitute a large part of our energy intake and have known metabolic effects, may also be part of the equation.
A study recently published in the British Journal of Nutrition (BJN) has sought to examine the relationship between the intake of fatty acids (FAs) and the incidence of type 2 diabetes. The study looked at the impact of total FA intake, but also focused in particular on omega-3 and omega-6 polyunsaturated fatty acids (PUFAs), which tend to be the most prevalent forms of fatty acids in western diets.
Data for the study was drawn from the Etude Epidémiologiqueauprès des femmes de la MutuelleGénérale de l’EducationNationale (E3N), which is an ongoing French cohort study involving 98 995 women born between 1925 and 1950. E3N data is collected via questionnaires that participants mail in every 2–3 years, and from drug reimbursement records that have been available through a database since 2004.
The BJN study looked at E3N data between 1993 and 2011, and followed 71 334 women who did not have type 2 diabetes at baseline. Cases of subsequent development of diabetes were identified through responses on later questionnaires, or through reimbursement claims for diabetes drugs.
FA consumption in 1993 was estimated based on a questionnaire issued to E3N participants in that year which asked 208 questions about dietary habits. The dietary information was then evaluated using a French national food composition database, to produce measures of various types of fats (saturated, monounsaturated, polyunsaturated, trans) consumed by participants.
Researchers also broke down the PUFA fat category, to produce estimates of omega-3 and omega-6 consumption, and then broke the omega PUFA’s down even further, to produce estimates of consumption of different types of each PUFA – linoleic acid and arachidonic acid (for omega-6); and α-linolenic acid, EPA, DPA and DHA (for omega-3).
Statistical analysis of the data suggested a correlation between high omega-3 consumption and development of type 2 diabetes. This correlation persisted even after taking account of possible confounding factors such as overall FA consumption, and body mass index (BMI) scores.
In addition, the BJN study found an association between total PUFA consumption and onset of type 2 diabetes. However, the association appeared to apply only to non-overweight women. This contrasts with the increased risk associated with high omega-3 consumption, which was found to apply to all women, regardless of BMI.
Within the omega-3 category, researchers found that high DPA and α-linolenic acid intakes were associated with increased risk of developing type 2 diabetes, although in the case of α-linolenic acid, this effect applied only to overweight women. Within the omega-6 category, only arachidonic acid consumption was associated with increased risk of type 2 diabetes.
Based on these results, the authors of the BJN study express caution about following a diet that is high in PUFAs or omega-3s. This appears to conflict with other evidence suggesting that PUFAs, and particularly omega-3s, provide benefits for cardiovascular health. The authors suggest that further research is warranted to better understand the associations between the types of PUFAs and the risk for type 2 diabetes.
Written By: Linda Jensen