Marine omega-3 intake is low among type 2 diabetics; higher intake associated with lower triglycerides

June 8, 2009

Patients with type 2 diabetes aren't meeting the recommended daily intake of marine omega-3 fatty acids. In fact, their consumption of marine omega-3 fatty acids is less than one fourth of the recommendation put forth by the American Diabetes Association (ADA).

Patients with type 2 diabetes aren't meeting the recommended daily intake of marine omega-3 fatty acids. In fact, their consumption of marine omega-3 fatty acids is less than one fourth of the recommendation put forth by the American Diabetes Association (ADA).

Adding even a small amount of marine omega-3 fatty acids to the diet of patients with type 2 diabetes could lead to favorable changes in the levels of triglycerides and high-density lipoprotein (HDL) cholesterol, says Maria Belalcazar, MD (pictured left), who presented data from a subset of the Look AHEAD (Action for Health in Diabetes) study.

Although no solid data exist on which to base a recommendation for omega-3 consumption in patients with type 2 diabetes, the ADA suggests at least 1,000 mg per day, consistent with the American Heart Association's recommendation in patients with coronary heart disease (CHD). Diabetes is considered a CHD risk equivalent by the National Cholesterol Education Adult Treatment Panel III, and treatment guidelines reflect the substantially increased risk of CHD, events in patients with diabetes.

The study presented here included 2,397 patients who were enrolled in Look AHEAD and for whom dietary information was captured at baseline. Look AHEAD is a multicenter, US-based trial in which obese participants with type 2 diabetes have been randomized to either a diabetes education and support control group or to a lifestyle intervention targeting primarily weight loss and physical activity.

To be eligible, patients had to have a body mass index (BMI) greater than 25 kg/m² (or >27 kg/m² if on insulin), a hemoglobin A1c (HbA1c) less than 11%, and a blood pressure of 160/100 mmHg or less. Their mean BMI at baseline was 36 kg/m², and their mean waist circumference was 114 cm.

Participants in this analysis completed a Food Frequency Questionnaire, of which 8 of the 134 items were devoted to omega-3 fatty acid intake.

The mean daily intake of marine omega-3 fatty acid was 162 mg per day. African Americans had a higher daily consumption of marine omega-3 fatty acid than other ethnicities examined, but their median intake was still very low at 205 mg per day, notes Dr. Belalcazar, an endocrinologist at the University of Texas Medical Branch, Dallas.

Three fourths of the participants had omega-3 fatty acid intake of less than 200 mg per day.

Even at these low levels of intake, a multivariate regression model showed that marine omega-3 fatty acid intake was strongly and inversely associated with triglyceride level. There was also a weak association with HDL cholesterol. These associations persisted after adjusting for lipid medications, HbA1c level, fitness, dietary fat intake, saturated fat intake, weight, carbohydrate intake, and race/ethnicity.

There was no association between marine omega-3 intake and HbA1c, glucose level, low-density lipoprotein cholesterol, and measures of adiposity.

"Don't underestimate the importance of fish intake," says Dr. Belalcazar. "Even at low levels, there is the potential that even slightly increasing fish intake can have a positive impact on triglycerides and possibly on HDL."