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Research Roundup: Recent Omega-3 Findings in Cardiovascular & Eye Health

Ω-3s Further Reduce Lipids with Statin Treatment

Over all, statins lower high triglycerides by 10-20% (or more if baseline levels are greatly elevated). EPA and DHA are also known to lower elevated triglycerides by inhibiting their release from the liver, and by increasing their rate of clearance from plasma. Is there value in combining statins with omega-3 supplements?

High dose omega-3 supplementation does appear to benefit patients, at least when triglyceride levels remain elevated despite statin use, according to results of a multicenter controlled trial of patients with hypercholesterolemia and at high risk for CVD (1).

After a 4-week run in treatment period with 20 mg daily of rosuvastatin, 201 patients with residual elevated triglycerides (mean 263 mg/dL) remained on the statin and were randomized to receive omega-3 (1,520 mg DHA + 1,840 mg EPA) or placebo for 8 weeks.

Average triglyceride levels decreased by 26% in the omega-3 group vs. 2% reduction in placebo takers. A greater reduction in non-HDL cholesterol of 11% was also seen in those taking the statin with omega-3s compared to 2% in those taking stain alone.

Higher Fish Intake Linked to Less Severe DR

Recent studies have shown favorable associations between fish consumption and diabetic retinopathy (DR). A relative decrease in risk for sight-threatening DR of 48%, for example, was seen in a Spanish population of type 2s consuming at least 500 mg/day of omega-3 and followed for 6 yrs. A newly published paper (2) lends some credence to this observation.

The study evaluated the association of dietary fish intake with varying severity of DR and retinal vascular caliber (RVC) in 357 Asians with type 2. RVC provides information about microcirculation in the eye and the risk of DR. Increasing frequency of fish consumption was significantly associated with lower odds of having severe DR. The likelihood of severe DR was reduced by almost 10% per a one serving increase of fish weekly. In addition, the highest level of fish intake was also associated with wider RVC among diabetics with no signs of diabetic retinopathy.

Meta-analysis: Ω-3s May Reduce Resting Heart Rate

Elevated resting heart rate (HR) has emerged as a risk factor for all-cause and cardiovascular mortality. It’s been suggested that marine omega-3s may influence sudden cardiac death by reducing HR. In a recently conducted meta-analysis of 51 randomized controlled trials that included about 3000 people, researchers found that EPA and DHA supplementation mildly but significantly reduced HR (mean − 2.23 beats per minute) compared to controls (3). In the few trials where DHA and EPA were administered alone, DHA rather than EPA slowed HR.

The authors note that “the HR of the majority of participants included in this meta-analysis was within normal range – the state where reducing HR is conventionally not a medical indication. At the population level, however, such HR reduction may have significant public health implications, as a reduction of 3.2 beats per minute would roughly correspond to a 7.5% lower risk of sudden cardiac death.”

Dietary Fatty Acid Intake Linked to Glaucoma 

It is important to know whether polyunsaturated fatty acid (PUFA) intake influences the development of glaucoma, as it could offer a modifiable risk factor for the disease.  An analysis of data from 3,865 participants in the National Health and Nutrition Examination Survey offers some insight into the relationship of PUFA consumption and glaucoma (4).

The study found that increased daily levels of EPA and DHA were linked to significantly lower risks of glaucoma (OR, 0.06 for EPA and for DHA). Higher levels of total PUFAs (omega 6 + omega 3), however, significantly raised glaucoma risk (OR, 2.84 and 2.97 for 2nd and 3rd quartiles respectively). The authors hypothesize that increasing the ratio of omega-3 to -6 while watching overall PUFA intake, could be glaucoma-protective.

References

1. Kim CH, et al. Efficacy and safety of adding omega-3 fatty acid in statin-treated patients with residual hyper-triglyceridemia: ROMANTIC Trial. Clin Ther. 40:83-94, 2018.
2. Chua J, et al. The relationship of dietary fish intake to diabetic retinopathy and retinal vascular caliber in patients with type 2 diabetes. Sci Rep. 8:730, 2018. 
3. Hidayat K, et al. Effect of omega-3 long-chain poly-unsaturated fatty acid supplementation on heart rate: a meta-analysis of randomized controlled trials. Eur J Nutr. ePub Dec. 28, 2017. 
4. Wang YE, et al. Association of dietary fatty acid intake with glaucoma in the U.S. JAMA Ophthalmol. ePub Dec. 21, 2017.