Researchers have been investigating the effects of omega-3 fatty acids on cardiovascular disease and mortality since they were associated with the incredible heart health of the Greenland Eskimo in the 1970s. As research on omega-3 fats continues to evolve, more and more evidence begins to clarify the potential effects and uses of these unique nutrients on health and longevity.

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As we strive to live longer, healthier lives, understanding the role that omega-3s play could make a difference in health outcomes and quality of life. This article will delve into the research surrounding the omega-3 fatty acid DHA and its impact on cardiovascular health and lifespan. By doing so, we hope to provide you with up-to-date evidence on how DHA may contribute to health and well-being and how you can apply it to daily life.

 

What is DHA, and where does it come from?

Docosahexaenoic acid (DHA) is a specific type of omega-3 polyunsaturated fatty acid (PUFA). PUFAs are differ from other fatty acids by having two or more double bonds within the fatty acid chain. Omega-3 PUFAs are named by their first double bond located three carbons from the methyl end of the carbon chain. DHA is a long-chain omega-3 PUFA and contains 22 carbon atoms. These small details in chemical structure may seem insignificant, but the double bonds present in PUFAs contribute to their health and wellness capabilities and benefits.

The human body can only form carbon-carbon double bonds after the ninth carbon; therefore, omega-3 fatty acids, like DHA, must be consumed from the diet to obtain adequate amounts to provide health benefits. DHA is found primarily in fatty fish, fish oils, and seafood sources. For example, fish with the highest amount of DHA include salmon, sardine, herring, and anchovy. DHA is initially synthesized from microalgae, which eventually builds up in fish tissue through the food chain. Therefore, microalgae oil is also a valuable DHA source for those who prefer not to consume fish or other seafood.

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Professional health organizations have yet to agree on specific omega-3 intake recommendations. The American Heart Association recommends eating two servings (6 ounces cooked) of fatty fish per week. Other analyses report that 2-3 g per day of EPA+DHA from food or supplements provides health benefits, and up to 4 g per day is considered safe and effective. Yet, the mean intake of omega-3 fatty acids DHA + EPA in the United States is much lower than these guidelines at ~100 mg per day, and the mean Omega-3 Index in the United States is ~5.4%. 

 

What are the Health Benefits of DHA?

For many years, research has focused on the potential health benefits of omega-3 fatty acids. Some of the areas of health that omega-3 has been linked to include cardiovascular disease (CVD) and its risk factors, infant health and neurodevelopment, Alzheimer’s disease, dementia and cognitive function, age-related macular degeneration, cancer, allergies and other immune-related conditions, and infant health and neurodevelopment.

Of these health benefits, omega-3 effects on CVD have been studied the most, and some of the reported health outcomes include beneficial effects on arrhythmias, atherosclerosis, inflammation, and thrombosis. Furthermore, they have been reported to improve endothelial function, lower blood pressure, and lower triglycerides. Research demonstrates that treatment with omega-3 fats EPA+DHA reduces the risk of CVD mortality and fatal cardiovascular events. An Omega-3 Index over 8% has been associated with the greatest cardioprotection and may be a relevant and easily modified risk factor for CVD and cardiovascular-related death.

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DHA, in particular, is critical for all stages of life. High amounts of DHA are found in the brain’s gray matter and the retina’s outer rod segments and are an essential structural component of neural tissues. The chemical structure of DHA, with its long carbon chain and multiple double bonds, allows it to incorporate into cellular membranes and enhance cellular membrane fluidity. It also serves as a precursor for metabolites that enhance neuronal differentiation and growth and serve as anti-inflammatory compounds system-wide.

An extensive review of the health benefits of DHA was published in 2021, so further details won’t be provided here. Still, despite the recent publication of that review, growing evidence demonstrates the impact DHA can have on health outcomes and lifespan.

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Results from the Largest Study on the Relationship between DHA Status and Mortality

An April 2024 study published in the Mayo Clinic Proceedings aimed to determine the relationship between DHA levels and risk for all-cause mortality and cause-specific mortality in the United Kingdom Biobank (UKBB). Within the original cohort assessed in this large-scale biomedical database, ~117,700 adults were randomly chosen to analyze plasma DHA%.

Outcomes measured were mortality and cause-specific mortality, classified as cardiovascular (CV)-related, cancer-related, or other. The relationships between DHA status and outcomes were examined by quintile of plasma DHA%. At baseline, the median DHA% (estimated median Omega-3 Index %) from Q1-Q5 were 1.25(3.75), 1.64(4.96), 1.93(5.86), 2.26(6.89), 2.85(8.72) respectively. Individuals were followed up for approximately 12-14 years.

The researchers found that DHA levels were significantly and inversely associated with risk of death from all causes and cause-specific deaths due to CVD, cancer, and other causes. When comparing the highest quintile (Q5) with the lowest (Q1), there was a 21% lower risk across all outcomes, all-cause, CVD, cancer, and other mortality.

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The researchers then went a step further and used the data to update a previous meta-analysis that pooled data from 17 prospective cohort studies to explore the relationship between omega-3s and total and cause-specific mortality. When combining the data and comparing Q5 with Q1, the risk was decreased for all-cause mortality, CVD death, cancer death, and death from all other causes by 17%, 21%, 19%, and 15%, respectively. The present outcomes demonstrate, yet again, that an Omega-3 Index of ~8% is an ideal target for cardioprotective (and other) benefits.

One of this study’s strengths is the use of plasma DHA levels to establish the relationship to health outcomes. A few studies (1, 2, 3, 4) have examined the positive effects of self-reported intake of fish/seafood or use of fish oil supplements on the risk of death. Yet, self-reported intake data can be unreliable, and measures of blood omega-3 levels provide a more accurate and objective measure of omega-3 intake.

Furthermore, the authors offered pointed guidance to increasing the Omega-3 Index. To get from the United States average Omega-3 Index of 5.4% to the recommended 8%, a person must consume ~1,000 mg/d of EPA+DHA. Moreover, for a person to go from Q1 (3.5%) in this study to 8%, they would require ~1,600 mg/d EPA+DHA. These amounts can be accomplished through food intake, where 6 ounces of salmon provides approximately 2 g of omega-3s, or through supplementation.

 

Summary

The omega-3 fatty acid DHA is essential throughout the lifespan and has been found to impact health outcomes related to fetal development, allergies and immunity, cardiovascular disease, certain types of cancers, and more. A recent publication, which is the largest-ever study to examine the relationship between DHA status and mortality, has added to the growing body of evidence establishing this molecule’s essential role in human health.

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Reporting a 21% lower risk of all-cause mortality and cause-specific deaths due to CVD, cancer, and other causes, DHA may be a modifiable lifestyle factor that can have a significant impact on human longevity. Like several studies completed in the past, this recent publication notes that an Omega-3 Index of 8% or more is the target range that receives the most health benefits.

These statements have not been evaluated by the Food and Drug Administration. This test is not intended to diagnose, treat, cure, prevent or mitigate any disease. This site does not offer medical advice, and nothing contained herein is intended to establish a doctor/patient relationship. OmegaQuant, LLC is regulated under the Clinical Laboratory improvement Amendments of 1988 (CLIA) and is qualified to perform high complexity clinical testing. The performance characteristics of this test were determined by OmegaQuant, LLC. It has not been cleared or approved by the U.S. Food and Drug Administration.

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