Nut Consumption Linked to Lower AF Risk

May 01, 2018

Eating nuts several times a week may play a role in reducing the risk for atrial fibrillation (AF) and possibly heart failure, a new study suggests.

In the large prospective study, Swedish researchers found an inverse association between nut consumption and incident AF, which remained after adjustment for multiple risk factors. Eating nuts three or more times a week was associated with an 18% reduced risk for AF.

They also observed inverse associations of nut consumption with risk for total and nonfatal myocardial infarction (MI), heart failure, and abdominal aortic aneurysm after adjustment for age and sex. However, adjustment for other risk factors attenuated these associations and only a nonlinear association with heart failure persisted.

"Since only a small proportion of this population had moderate (about 5%) or high (<2%) nut consumption, even a small increase in nut consumption may have large potential to lead to a reduction in incidence of atrial fibrillation and heart failure in this population," they conclude.

The study was published online in Heart on April 16.  

The researchers, led by Susanna C Larsson, PhD, Karolinska Institutet, Stockholm, Sweden, note that nuts are rich sources of unsaturated fatty acids, protein, fiber, minerals, vitamin E, folate, and other bioactive compounds, such as phenolics and phytosterols. Previous studies have suggested that eating nuts may have antioxidant and anti-inflammatory effects and can improve blood lipids and endothelial function and prevent weight gain.

Meta-analyses of prospective studies have shown that nut consumption is inversely associated with death from cardiovascular disease (CVD), total coronary heart disease, and total stroke, but data in relation to incidence of specific CVD outcomes, such as MI, heart failure, and AF, are scarce.

To further evaluate the potential role nuts on specific cardiovascular outcomes, the researchers analyzed data from two population-based cohort studies — the Cohort of Swedish Men and the Swedish Mammography Cohort — in which 61,364 people had completed a food-frequency questionnaire and were followed up for 17 years through linkage with the Swedish National Patient and Death Registers.

Results showed that nut consumption was inversely associated with risk for MI, heart failure, AF, and abdominal aortic aneurysm in the age-adjusted and sex-adjusted analysis.

People who ate nuts tended to be better educated and to have healthier lifestyles than those who didn't include nuts in their diet. They were less likely to smoke or to have a history of high blood pressure. And they were leaner, were more physically active, drank more alcohol, and ate more fruit and vegetables.

After adjustment for these and other factors, most associations with cardiovascular conditions were attenuated, and only a linear, dose-response association with AF (P trend = .004) and a nonlinear association (P nonlinearity = .003) with heart failure remained.

Compared with no consumption of nuts, the hazard ratios for AF across categories of nut consumption were 0.97 (95% confidence interval [CI], 0.93 - 1.02) for one to three times per month, 0.88 (95% CI, 0.79 - 0.99) for one to two times per week, and 0.82 (95% CI, 0.68 - 0.99) for three or more times per week.

Each additional portion of nuts eaten during the week was associated with a 4% reduction in AF risk.

A reduction in heart failure was seen with moderate (but not high) nut consumption, with hazard ratios of 0.87 (95% CI, 0.80 - 0.94) for eating nuts one to three times per month, 0.80 (95% CI, 0.67 - 0.97) for one to two times per week, and 0.98 (95% CI, 0.76 - 1.27) for three or more times per week.

The researchers suggest this might be related to increased weight gain with high consumption.

Nut consumption was not associated with risk for aortic valve stenosis, ischemic stroke, or intracerebral hemorrhage.

The researchers point out that they cannot rule out the possibility that the observed associations are due to unmeasured or residual confounding, such as that caused by income and occupation, because these were not known.

But they say the strength of the study lies in its large size and the large number of cardiovascular disease cases reported.

This study was supported by the Swedish Research Council.  Larsson has disclosed no relevant financial relationships.

Heart. Published online April 16, 2018. Full text 

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