Researchers have found a link between intake of some fatty acids and greater risk of type 2 diabetes among women.
Study investigator Dr. Guy Fagherazzi, of the INSERM Centre for Research in Epidemiology and Population Health (CESP) and University Paris-Saclay - both in France - and colleagues report their findings in the journal Diabetologia.
The researchers also recently presented their results at the European Association for the Study of Diabetes (EASD) General Assembly in Munich, Germany.
Omega-3 fatty acids are a form of polyunsaturated fatty acids (PUFAs) that come in three main forms: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
ALA is present in some vegetable oils - including canola and soybean oils - while EPA and DHA are found in fatty fish and shellfish, including salmon, trout, tuna, and mussels.
Docosapentaenoic acid (DPA) is another form of omega-3, present in fatty fish and some red meats, though its health benefits are not as well understood.
Omega-3 fatty acids are also available as dietary supplements; according to the National Institutes of Health, around 18.8 million adults and 664,000 children in the United States report having taken an omega-3 supplement in the past 30 days.
Not only are omega-3 acids needed for a wealth of bodily functions - including muscle activity, blood clotting, digestion, and reproduction - they have been associated with an array of health benefits.
For example, Medical News Today recently reported on a study that found omega-3 improves heart damage and function after a heart attack, while another study linked omega-3 to reduced breast cancer risk.
When it comes to type 2 diabetes, however, Dr. Fagherazzi and colleagues say the effects of omega-3 and other fatty acids remain controversial; some studies say they lower the risk of type 2 diabetes, while others suggest they have the opposite effect.
26 percent greater type 2 diabetes risk with high omega-3 intake
With the aim of gaining a better understanding of how fatty acids influence type 2 diabetes risk, the team analyzed the data of 71,334 women who were part of the French prospective E3N cohort study.
Dietary questionnaires were used to assess fatty acid consumption of the women at study baseline, in 1993. Over an average of 14 years follow-up, information on diabetes onset was gathered through health questionnaires and drug reimbursement claims.
Using computer modeling, the researchers estimated how fatty acid intake related to women's risk of type 2 diabetes.
Compared with women in the lowest 33 percent of omega-3 fatty acid intake (less than 1.3 grams daily), those in the highest 33 percent (omega-3 intake of at least 1.6 grams daily) were found to be at 26 percent increased risk of type 2 diabetes.
The team then divided the women into two groups based on their body mass index (BMI): women with a BMI greater than 25kg/m2 (overweight) and those with a BMI below 25kg/m2.
The researchers found that non-overweight women in the top third for overall fatty acid consumption (greater than 15.3 grams daily) were at 22 percent greater risk of type 2 diabetes, compared with those in the lowest third (less than 12.0 grams daily).
Looking specifically at omega-3 intake among the two groups, the team found overweight women in the highest 33 percent were at 19 percent greater risk of type 2 diabetes, while non-overweight women were at 38 percent greater risk, compared with women in the lowest 33 percent of omega-3 consumption.
DPA, arachidonic acid linked to diabetes risk
Next, the researchers looked at type 2 diabetes risk dependent on intake of specific types of fatty acids.
They found that women in the top third for intake of DPA were at 54 percent greater risk of type 2 diabetes if they were overweight and at 45 percent greater risk if they were not overweight, compared with women in the lowest third.
Among overweight women, those in the highest 33 percent for intake of ALA (more than 1.14 grams daily) had a 17 percent increased risk for type 2 diabetes, compared with those in the lowest 33 percent (less than 0.19 grams daily).
On assessing the effects of omega-6 fatty acids - present in vegetable oils - the researchers found that non-overweight women in the top third for intake of arachidonic acid (more than 0.25 grams daily) had a 50 percent increased risk of type 2 diabetes, while overweight women in this group had a 74 percent increased risk, compared with those in the lowest third.
After accounting for a number of potential confounding factors - including the food sources of fatty acids - the researchers found that the link between high intakes of DPA and arachidonic acid and increased risk of type 2 diabetes remained.
The primary food sources of DPA and arachidonic acid were meat and seafood, the researchers report.
Commenting on their findings, the researchers say:
"Different polyunsaturated fatty acids appear to have different effects regarding the risk of developing type 2 diabetes. A high consumption of docosapentaenoic acid and arachidonic acid may contribute to the development of type 2 diabetes.
We wouldn't necessarily recommend cutting these sources out of our diet, but perhaps diminishing meat intake, as it is often consumed in quantities much greater than our nutritional requirements."