Adherence to healthy dietary patterns, like the DASH (Dietary Approach to Stop Hypertension) diet, based on the principles of the Mediterranean diet, recommending higher intakes of fruits, vegetables, whole grains, nuts and legumes and low-fat dairy and lower intakes of red and processed meat, sugar-sweetened beverages and sodium, have been associated with lower risk of all-cause mortality, cardiovascular mortality and incidence of heart failure (HF), although in some US studies the findings were controversial. This Swedish cohort study aimed to clarify the role of the DASH diet followed for a long-term basis in the prevention of HF, examining also the possible impact of food substitutions.
Dates were obtained from two large cohorts with 76,122 middle aged and elderly men and women (the Cohort of Swedish Men (CO,SM) and the Swedish Mammography Cohort (SMC)), using a self-reported questionnaire for two periods, in late 1997 and 2009. The 96-item Food Frequency Questionnaire (FFQ) asking their average intake of foods and meals during the last 12 months was used, while in the follow-up in 2009 the questionnaire was extended to include new foods on the market and usual foods consumed at the time. Diet score including 8 components (fruits, vegetables, nuts and legumes, low-fat dairy, whole grains, sodium, sweetened beverages, and red and processed meat) was used to calculate adherence to the DASH diet. HF incidence was ascertained using the Swedish Patient Register (ICD10).
According to the multivariate analysis, greater and long-term adherence to the DASH diet was associated with a lower risk of HF in middle-aged and elderly adults. Replacing 1 serving/day of red meat with 1 serving/day of fruits, vegetables, nuts and legumes, low-fat dairy or whole grains was also associated with an 8-12% lower risk of HF. On the other hand red meat should be included in the diet as an important source of iron, but only in low intake (around 50 g/day), as well as low-fat dairy (around 200 g/day), since both were associated with a lower risk of HF.
No specific benefit from DASH was observed for subgroups of patients with hypertension and diabetes, possibly explained due to low representation in the total sample and the fact that the diagnoses of both hypertension and diabetes at the baseline was self-reported. Using self-reported questionnaire like FFQ for dietary intake could also produce possible bias. A possible confounder factor observed was that those subjects who adhered to the DASH diet reported overall healthier lifestyle, compared with those who did not.
Adherence to DASH diet in the study population i.e. men and women aged 45-85 years, could prevent 13 to 25 cases per 10,000 person-years. Promoting healthier dietary habits particularly contemporary DASH diet, would be an important contribution to population-based primary prevention strategy of HF.