Statistics from Altmetric.com
Implications for practice and research
A diet rich in natural antioxidants may reduce the risk of developing heart failure.
Well-designed intervention studies are needed to investigate the effect of a diet rich in antioxidants on heart failure incidence.
Heart failure is a syndrome comprising symptoms such as breathlessness alongside objective evidence of cardiac dysfunction. This is a common condition with a considerable economic impact on health services.1 Nutritional intake and status appear to be important in heart failure. Non-intentional weight loss in the setting of heart failure (cardiac cachexia) is an independent predictor of mortality.2 Heart failure is associated with increased levels of oxidative stress3 and observational studies suggest that affected patients have reduced intake and suboptimal status of a number of antioxidant dietary micronutrients, such as selenium, vitamin C and vitamin E.4 Rautiainen and colleagues investigated the relationship between dietary antioxidant intake and risk of incident heart failure.
This was a prospective, population-based cohort study. The authors analysed a questionnaire which had been completed in 1997 by 33 713 women (mean age 61 years) living in Sweden with no history of cancer, myocardial infarction, angina pectoris, stroke or congestive heart failure. The questionnaire included items on risk factors for cardiovascular disease and a 96-item food frequency questionnaire (FFQ) assessing dietary intake over the previous 12 months. The total antioxidant capacity of the diet was estimated by multiplying the average frequency of consumption of each food type by its oxygen radical absorbance capacity (a direct measure of antioxidant capacity). Women were followed for incident heart failure through December 2009, defined as heart failure hospitalisation (determined from the Swedish Hospital Discharge Registry) or heart failure mortality (determined from the Swedish Cause of Death Registry). Rate ratios were estimated using Cox proportional hazards models with age as the time scale and reported as age-adjusted relative risk (RR).
During 11.3 years (394 059 person-years) of follow-up, there were 894 cases of incident heart failure (769 cases of hospitalisation and 125 deaths). The cohort was divided into quintiles based on total antioxidant capacity of the diet and there was an inverse association with incident heart failure (p<0.001). The crude incidence rate was 18/10 000 person-years in the highest quintile versus 34/10 000 person-years in the lowest quintile (RR=0.50, 95% CI 0.40 to 0.62). This association remained statistically significant after adjustment for educational level, smoking status, body mass index, physical activity, diabetes mellitus, family history of myocardial infarction, alcohol consumption, total energy intake, dietary supplement use and incident myocardial infarction.
This observational study suggests that a diet rich in antioxidants may help prevent the development of heart failure. The strengths include the prospective design, the large number of patients, the long duration of follow-up and the use of robust clinical endpoints. Limitations include the observational design, which makes it impossible to exclude unmeasured confounders, such as concurrent medication use, as a cause for the observed results. The study population was limited to middle-aged to elderly women from a single country. The FFQ was administered only once during the course of the study. It is, therefore, not possible to exclude a change in dietary intake over the period of follow-up. No biochemical assessment of antioxidant status was performed to confirm the findings of the FFQ. Finally, the diagnosis of heart failure was based solely on the identification of a hospital discharge or cause of death code. Individuals managed only as outpatients were, therefore, excluded.
The results of this study are in keeping with previous observational studies, demonstrating an inverse association between risk of developing heart failure and blood concentration of antioxidant micronutrients,5 and support the case for undertaking well-designed, large-scale intervention studies to investigate the effect of a diet rich in antioxidants on heart failure incidence.
Competing interests None.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.