Fish Intake Prevents Atrial Fibrillation

Mozaffarian D, “Fish Intake and Risk of Incident Atrial Fibrillation. Circulation 2004;110:368-373.

Until now, there has been no proven dietary intervention for people with the common clinical condition, atrial fibrillation (AF). AF is more common in people over 65 years old. In past studies, we have seen that fish intake may lower blood pressure, reduce systemic inflammation, and improve left ventricular diastolic function, each of which could favorably affect risk of AF. Fish consumption also appears to reduce risk of fatal ventricular arrhythmias.

This population based, prospective study included over 5000 men and women over 65 years of age, comparing average intake of different kinds of fish with risk of developing AF over a 12-year period. To begin, the researchers confirmed that broiled fish, baked fish, and tuna fish all correlated with increases in omega-3 (n-3) fatty acid (EPA and DHA) blood levels. Fried fish and fish sandwiches did not have any substantial effect on n-3 PUFA in the blood.

The results confirmed the known health benefits of eating fish; People eating tuna or other broiled/ baked fish 1-3 times per week developed 25% less AF, and eating these fish 5 or more times per week resulted in 35% less AF. This beneficial effect of fish consumption is presumably from the n-3 EFA content. Studies on fish oil consumption in humans have confirmed numerous cardiovascular benefits:
1. Lower blood pressure
2. Reduce markers of systemic inflammation (CRP)
3. Attenuate vasoconstrictive responses to angiotensin II
4. Improve arteriolar wall compliance
5. Improve left ventricular diastolic filling.
Considerable epidemiological, clinical trial, and animal experimental evidence also points to antiarrhythmic effects of n-3 fatty acids in fish.

In contrast, consumption of fried fish/ fish sandwich >1 serving per week actually had a 25% increased risk of developing AF. Frying can greatly alter a fish meal’s nutrient composition, increasing contents of n-6 fatty acids, trans-fatty acids, and oxidation products, particularly when oils are used repeatedly for frying.

Taking Fish Oil Supplements Can Prevent Dangerous Arrhythmia

Singer P, Wirth M, “Can n-3 PUFA reduce cardiac arrhythmias? Results of a clinical trial” Prostaglandins, Leukotrienes and Essential Fatty Acids 71 (2004) 153–159.

In a randomized, double blind, placebo-controlled study 65 patients with cardiac arrhythmias without coronary heart disease or heart failure were subdivided into 2 groups. 33 people were supplemented with encapsulated fish oil 3g/day totaling 1000 mg. EPA/DHA (n-3 PUFA) combined per day over 6 months. The other group (32 people) was given 3 g/day of olive oil as placebo.

Clinically, this editor is impressed with the results given the relatively low dose of EPA/DHA. This study used small 500-mg. capsules (18%EPA/12%DHA) either 2, tid or 3, bid. The equivalent dose of a common capsule of 300 EPA/200 DHA would be only 2 capsules per day! Even at this nominal dosage, the fish oil group experienced significant:

• Decrease of serum triglycerides
• Decrease of total cholesterol
• Decrease of LDL cholesterol
• Decrease of plasma free fatty acids and thromboxane B2
• An increase of HDL cholesterol
• Moreover, a reduced incidence of atrial and ventricular premature complexes, couplets and triplets were documented. Put more simply, severity of ventricular arrhythmia diminished significantly over the 6-months.

No changes were seen in the placebo (olive oil) group. Notably, olive oil does NOT appear to carry cardiovascular benefits like fish oil.

The researchers report that a recent trial Cardiac Arrhythmias Suppression Trial (CAST) “showed an even higher rate of death from arrhythmia in patients after myocardial infarction treated with antiarrhythmic drugs compared to patients assigned to placebo”. Therefore, with just 1 g/day of n-3 (EPA/DHA) PUFA supplementation, we can offer a reasonable regimen at low cost and little risk in clinical practice to our patients.