America’s “stroke belt” refers to a group of southeastern states that have much higher rates of heart attacks and strokes compared to the rest of the country. A new study published in Prostanglandins, Leukotrienes and Essential Fatty Acids shows that people living in these states also have remarkably low omega-3 levels as measured by the Omega-3 Index.
The Omega-3 Index is a blood test that measures the amount of omega-3s EPA and DHA in blood. Several studies have correlated a low Omega-3 Index with a higher risk of sudden cardiac death. An Omega-3 Index of 4% or below is considered “undesirable,” and 8-12% as “desirable.”
Since the 1960s, CDC data have consistently shown that people living in the stroke belt states – which generally include Alabama, Arkansas, Florida, Georgia, Indiana, Kentucky, Louisiana, Mississippi, North Carolina, Ohio, Oklahoma, South Carolina and Tennessee – are almost twice as likely to experience a stroke in their lifetime.
Researchers in the REGARDS study (The REasons for Geographic And Racial Differences in Stroke) attributed this alarming increase in the incidence of stroke to what’s been called the “Southern Dietary Pattern,” which typically includes excessive consumption of saturated fat, fried foods, eggs, processed meat, and sugar-sweetened beverages. Along with higher rates of heart disease and stroke, this dietary pattern has also contributed to far more cases of hypertension, obesity, and diabetes.
Omega-3 Levels in Stroke Belt Cities
Because little is known about the omega-3 EPA and DHA blood levels (i.e., Omega-3 Index) of people living in the stroke belt, researchers wanted to find out if there is a correlation stroke incidence and omega-3 intake. In other words, could omega-3s play a role in stroke prevention.
The people who participated in this study had their Omega-3 Index tested in free health screens across seven cities in the stroke belt region, including: Charleston, WV; Jacksonville, FL; Indianapolis, IN; Lexington, KY; Memphis, TN; Oklahoma City, OK; and Toledo, OH.
The screenings took place at church health fairs, malls, Departments of Public Health, medical clinics, and other public settings from October 2014 to November 2015. This project was organized by the Seafood Nutrition Partnership (SNP) in cooperation with local health partners, such as health insurance providers, schools of public health, local health clinics and centers.
In all, 2177 people had their Omega-3 Index measured. A startling 42% of those tested had an Omega-3 Index below 4%, which puts them at a 90% higher risk of sudden cardiac death. Only about 1% of those tested had an Omega-3 Index of 8% or above.
OmegaQuant’s Dr. Bill Harris, who was the lead author on this study, said “Since in other settings, a low Omega-3 Index is associated with increased risk for cardiovascular disease (CVD), this may be one factor contributing to the higher risk for CVD in this region of the US.”
The purpose of this study was to gather preliminary information on the O3I in people living in the “CVD” belt. Because screenings were generally conducted in lower income parts of town, the SNP cohort is likely to have been of a lower socio-economic status (SES). However, because researchers were unable to collect SES data on this cohort, no conclusions regarding SES and the Omega-3 Index can be drawn from this study.
When comparing the results of this study with general US population as well as other larger studies, like the Framingham Heart Study, Dr. Harris said “Our analysis suggests that the SNP cohort in these cities have depressed Omega-3 Index levels compared to Americans in general and to Framingham in specific. The fraction of individuals in the SNP cohort with an Omega-3 Index in the desirable zone (8%−12%) was 83% lower than that in a very large sample of Americans from a clinical laboratory dataset (i.e., 1.2% vs 7%), and the fraction in the undesirable zone (<4%) was 20% higher (i.e., 42% vs 35%).
“The logical extension of our findings that Omega-3 Index levels are low in this region is that raising the Omega-3 Index by increasing EPA and DHA intake could potentially reduce their elevated risk for CVD. There is accumulating evidence that higher intakes of fish and omega-3 capsules (both of which increase the Omega-3 Index) are good for the heart,” Dr. Harris said in the paper.
More specifically, support for increasing fish intake comes most recently from the NIH-AARP Diet and Health study. This study looked at risk for death from a variety of causes in over 420,000 older individuals as a function of reported fish intake. They found reductions in mortality from Alzheimer’s disease of 38% and 24% in women and men, respectively, between highest and lowest quintiles of non-fried fish intake. Reductions in all-cause mortality, CVD, cancer, and respiratory disease were all significant though smaller in magnitude.
The researchers the omega-3/stroke belt paper also pointed that besides taking fish oil supplements or eating more oily fish (salmon, mackerel, herring, sardines, albacore tuna, etc.), there are now several kinds of EPA/DHA-fortified foods (eggs, fruit juices, milk, bread, spreads, peanut butters) available to consumers. They believe with proper education regarding the selection, preparation and consumption of seafood, the overall health of communities with very low omega-3 levels could be significantly improved. The next step is getting these communities to accept omega-3s as one of the ways they can prevent strokes.
New Research on Omega-3 Levels in Heart Failure Patients
More and more studies are not only looking at omega-3 consumption and correlating that with health outcomes, but also evaluating omega-3 status. A recent example is a study published July 10th in the Journal of American College of Cardiology Heart Failure, which assessed omega-3 levels in heart failure patients.
The aim of this study was to determine if plasma EPA abundance is associated with reduced risk for primary heart failure (HF) events in the MESA (Multi-Ethnic Study of Atherosclerosis) trial.
To answer this question, researchers examined data from the MESA (Multi-Ethnic Study of Atherosclerosis) study, and specifically looked at whether plasma phospholipid EPA predicts primary heart failure incidence.
More than 6500 participants 45 to 84 years of age had EPA measured at baseline. During 13 years of follow-up, researchers found that those with a higher level of EPA were at reduced risk for heart failure.
Because this cohort contained a fair amount of middle-aged people, the role omega-3s can play in heart failure prevention takes on new meaning. And while the benefits of increasing omega-3 intake are quite clear, this adds another layer to the importance of being able to measure omega-3 levels.
As pointed out by Dr. Harris and his colleagues in the “stroke belt” paper discussed earlier in this blog, in 2018 alone three major clinical trials added even more support to the role omega-3s play in heart health.
One of these was the largest study of omega-3 and CVD ever conducted and included more than 25,000 subjects. Essentially, it found that, although the composite endpoint (which summed a variety of CVD events) was not significantly reduced, there was a 28% statistically significant reduction in heart attacks in the omega-3 group (which was given 840 mg of EPA+DHA per day for more than 5 years).
In another study, vascular death was reduced by 19% in patients with type 2 diabetes given the same dose of EPA and DHA for more than 7 years.
Finally, the REDUCE-IT study published last November showed that a high-dose (4 g/d) of EPA tested in statin-treated, hypertriglyceridemic patients for almost 5 reduced CVD events by 25%.