Abstract
OBJECTIVE: To assess the association of dietary fatty acids with cardiovascular disease mortality and total mortality among patients with type 2 diabetes. DESIGN: Prospective, longitudinal cohort study.
SETTING: Health professionals in the United States. PARTICIPANTS: 11 264 participants with type 2 diabetes in the Nurses’ Health Study (1980-2014) and Health Professionals Follow-Up Study (1986-2014).
EXPOSURES: Dietary fat intake assessed using validated food frequency questionnaires and updated every two to four years. MAIN OUTCOME MEASURE: Total and cardiovascular disease mortality during follow-up. RESULTS: During follow-up, 2502 deaths including 646 deaths due to cardiovascular disease were documented. After multivariate adjustment, intake of polyunsaturated fatty acids (PUFAs) was associated with a lower cardiovascular disease mortality, compared with total carbohydrates: hazard ratios comparing the highest with the lowest quarter were 0.76 (95% confidence interval 0.58 to 0.99; P for trend=0.03) for total PUFAs, 0.69 (0.52 to 0.90; P=0.007) for marine n-3 PUFAs, 1.13 (0.85 to 1.51) for α-linolenic acid, and 0.75 (0.56 to 1.01) for linoleic acid. Inverse associations with total mortality were also observed for intakes of total PUFAs, n-3 PUFAs, and linoleic acid, whereas monounsaturated fatty acids of animal, but not plant, origin were associated with a higher total mortality. In models that examined the theoretical effects of substituting PUFAs for other fats, isocalorically replacing 2% of energy from saturated fatty acids with total PUFAs or linoleic acid was associated with 13% (hazard ratio 0.87, 0.77 to 0.99) or 15% (0.85, 0.73 to 0.99) lower cardiovascular disease mortality, respectively. A 2% replacement of energy from saturated fatty acids with total PUFAs was associated with 12% (hazard ratio 0.88, 0.83 to 0.94) lower total mortality. CONCLUSIONS: In patients with type 2 diabetes, higher intake of PUFAs, in comparison with carbohydrates or saturated fatty acids, is associated with lower total mortality and cardiovascular disease mortality. These findings highlight the important role of quality of dietary fat in the prevention of cardiovascular disease and total mortality among adults with type 2 diabetes.
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Key Points
This study assessed the associations of major dietary fats with cardiovascular disease mortality and total mortality among adults with diabetes in two large prospective cohort studies. We hypothesized that quality of fats determines their associations with total and cardiovascular disease mortality among patients with type 2 diabetes. In two cohorts of US men and women, an inverse association of dietary PUFAs, including linoleic acid and marine n-3 PUFAs, with mortality due to cardiovascular disease or total mortality among patients with type 2 diabetes was found. In addition, animal derived MUFAs were associated with higher total mortality when compared with dietary carbohydrates.
Dietary guidelines for patients with diabetes recommend limiting trans fat intake and replacing saturated fats with unsaturated fats for maintaining good health. These recommendations are largely based on findings in general populations. Little is known about the associations of specific dietary fats with total and cardiovascular disease mortality among patients with diabetes who have altered metabolism of macronutrients. Among diabetes patients, higher dietary intake of total polyunsaturated fatty acids (PUFAs), α-linolenic acid, linoleic acid, and marine n-3 PUFAs is associated with lower total mortality. Intake of monounsaturated fats from animal sources is associated with higher total mortality. In an isocaloric model, theoretically replacing saturated fatty acids with PUFAs, especially linoleic acid, is associated with lower cardiovascular disease mortality. Increasing dietary PUFAs, especially linoleic acid and marine n-3 PUFAs, in replacement of saturated fatty acids, may facilitate long term survival among patients with diabetes.