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Low Omega-3 Index as an Overlooked Biomarker of Longevity and Its Association with Elevated All-Cause Mortality Risk

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dr Karunia Valeriani Japar

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Keywords: Omega-3 Index, All-Cause Mortality, Docosahexaenoic Acid (DHA), Eicosapentaneoic Acid (EPA), Longevity

Introduction

Despite extensive advancements in cardiovascular and nutritional sciences, one circulating biomarker remains relatively underrecognized for its significant association with overall mortality risk, the omega-3 index. The omega‑3 index, defined as the proportion of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) within erythrocyte membranes, reflects long-term omega‑3 status and has emerged as a robust predictor of cardiovascular and all‑cause mortality. Epidemiological evidence demonstrates that individuals within the lowest omega‑3 index quartile exhibit up to a 20% higher risk of all‑cause mortality compared with those attaining optimal levels, underscoring the public health relevance of this biomarker in longevity research .

Despite this evidence, suboptimal intake of long-chain omega‑3 fatty acids remains widespread. Global dietary analyses suggest that approximately 70–80% of adults fail to achieve recommended intakes of EPA and DHA, largely attributed to modern dietary shifts characterized by high consumption of omega‑6 fatty acids and reduced intake of fatty fish. This nutritional imbalance contributes to impaired resolution of inflammation, endothelial dysfunction, and alterations in membrane fluidity, all biological mechanisms implicated in accelerated aging and chronic disease development.

Understanding Omega- Fatty Acids: EPA and DHA

Omega‑3 fatty acids are long‑chain polyunsaturated fatty acids (PUFAs) that play structural and signalling roles in multiple organ systems, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) being the most physiologically relevant species in humans. EPA and DHA are predominantly incorporated into phospholipid membranes of erythrocytes, cardiomyocytes, endothelial cells, neurons, and retinal photoreceptors, where they modulate membrane fluidity, receptor function, and downstream inflammatory and electrophysiological pathways. The sum of EPA and DHA in erythrocyte membranes, expressed as a percentage of total fatty acids, termed the omega-3 index has therefore been proposed as an integrated biomarker of long‑term omega‑3 status and cardiovascular risk [1,2,3].

EPA exerts prominent effects on inflammatory resolution and vascular homeostasis through its conversion into specialized pro‑resolving mediators, as well as by attenuating production of arachidonic‑acid–derived pro‑inflammatory eicosanoids. Experimental and clinical data indicate that EPA‑rich omega‑3 status is associated with improved endothelial function, reduced triglyceride levels, favourable modulation of platelet activity, and potential benefits on mood and affect, partly via effects on cell membrane composition and monoaminergic signalling. These mechanisms contribute to a net anti‑atherothrombotic and cardioprotective profile [2,4].

DHA, in contrast, is the predominant omega‑3 PUFA in the brain and retina, where it constitutes a major structural component of neuronal and photoreceptor membranes. High DHA enrichment in neural tissues supports synaptic plasticity, neurotransmission, neurogenesis, and neuronal survival, thereby influencing cognitive performance, memory, and neurodevelopment across the lifespan. In the retina, DHA is critical for photoreceptor disc membrane integrity and visual signal transduction, with adequate status linked to optimal visual acuity and retinal function [3,5].

When present together, EPA and DHA exert complementary effects on cardiometabolic health. Combination EPA+DHA supplementation has been shown to lower circulating triglycerides, improve endothelial function, and modulate autonomic balance, contributing to reductions in cardiovascular risk. Observational cohort studies consistently demonstrate that higher circulating or erythrocyte levels of EPA and DHA are associated with lower rates of total and cardiovascular mortality. On the basis of these data, an omega‑3 index in the range of approximately 8–12% of total erythrocyte fatty acids has been proposed as an optimal target associated with the lowest risk of fatal coronary events, whereas values below 4% are associated with significantly elevated cardiovascular and all‑cause mortality risk [1,2,4,6,7].

Mechanisms Linking Omega-3 to Longevity

Low omega‑3 status appears to influence longevity through several interrelated molecular and physiological pathways that converge on inflammation, cardiometabolic health, neurodegeneration, and cellular aging. At the interface of these processes are specialized pro‑resolving mediators (SPMs), membrane biophysics, oxidative stress, and genomic stability, all of which are modulated by eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [8,9,10,11].

Inflammation and Cellular Signaling

EPA‑ and DHA‑derived SPMs, including resolvins and protectins, actively orchestrate the resolution phase of inflammation rather than merely suppressing pro‑inflammatory signalling. These mediators limit leukocyte infiltration, enhance efferocytosis of apoptotic cells, and promote tissue repair, thereby preventing the transition from acute to chronic low‑grade inflammation that characterizes aging (“inflammaging”). In clinical and translational models, low availability of omega‑3 PUFAs is associated with reduced SPM generation, persistence of vascular and tissue inflammation, and progression of atherosclerosis and other chronic age‑related pathologies [8,9,11].

Cardiometabolic Regulation

Omega‑3 fatty acids exert multiple effects on cardiometabolic regulation, including improvements in plasma triglyceride levels, modulation of lipoprotein profiles, and favourable impacts on endothelial function. At the vascular level, EPA and DHA enhance endothelial nitric oxide (NO) bioavailability and reduce oxidative stress, contributing to improved vasodilation and attenuation of endothelial dysfunction, a key early event in atherogenesis and vascular aging. Experimental and clinical data also indicate that omega‑3 PUFAs modulate mitochondrial and endoplasmic reticulum stress pathways in insulin‑sensitive tissues, thereby influencing insulin signalling and potentially mitigating the development of insulin resistance and metabolic syndrome, both of which are strongly linked to reduced lifespan [10,12,13].

Neuroprotection and Cognitive Aging

DHA is highly enriched in neuronal membranes, where it supports membrane fluidity, synaptic function, and neurotrophic signalling, all of which are critical for learning, memory, and executive function. Through incorporation into phospholipids and subsequent conversion into neuroprotective SPMs, DHA attenuates microglial activation and neuroinflammatory responses implicated in age‑related cognitive decline and neurodegenerative disease. Lower omega‑3 status has been associated with impaired cognitive performance and increased risk of dementia in observational studies, suggesting that inadequate DHA availability may accelerate brain aging and shorten health span by promoting neurodegenerative processes [3,11,13,14,15].

Telomere and Mitochondrial Effects

Emerging evidence links omega‑3 status to markers of cellular aging, including telomere dynamics and mitochondrial function. In a cohort of patients with stable coronary artery disease, higher baseline blood levels of marine omega‑3 fatty acids were inversely associated with the rate of leukocyte telomere shortening over five years, suggesting a potential protective effect on genomic stability. Mechanistically, omega‑3 PUFAs may reduce mitochondrial reactive oxygen species production, ameliorate mitochondrial and endoplasmic reticulum stress, and improve bioenergetic efficiency in insulin‑sensitive tissues, collectively contributing to slower cellular aging and reduced risk of age‑related chronic disease [1,16,17,18].

Taken together, these converging pathways provide a biologically plausible framework by which low omega‑3 levels can accelerate multisystem aging, increase vulnerability to chronic disease, and ultimately shorten lifespan.

Optimizing Omega-3 Intake: Food First, Then Supplement

Optimizing omega‑3 intake is best approached through a combination of regular consumption of marine foods and targeted supplementation when dietary intake is insufficient. This strategy supports attainment of intakes associated with cardiometabolic and neurocognitive benefits while minimizing exposure to contaminants and unnecessary excipients [19].

Dietary Sources

For most adults, habitual intake of fatty fish remains the primary and most physiologically appropriate strategy to achieve meaningful eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exposure. Epidemiological and guideline-based analyses suggest that consuming approximately two to three servings of fatty fish per week, equivalent to roughly 2–3 ounces (60–85 g) per day on average can provide on the order of 0.8–1.25 g/day of combined EPA+DHA, a range associated with cardioprotective effects. Species such as salmon, sardines, mackerel, and herring are particularly rich sources and can materially contribute to achieving an omega‑3 index in the desirable range for cardiovascular risk reduction [19,20].

Although plant foods such as flaxseed, chia seeds, and walnuts are valuable sources of alpha‑linolenic acid (ALA), their capacity to raise tissue EPA and DHA levels is limited because endogenous conversion is inherently inefficient. Stable isotope and intervention studies indicate that ALA conversion to EPA typically ranges from about 5–8%, whereas conversion to DHA is often below 1–5%, and may be further suppressed in the context of high dietary omega‑6 intake. As a result, reliance on ALA alone is unlikely to achieve EPA/DHA intakes or omega‑3 index levels associated with reduced cardiovascular and all‑cause mortality risk, reinforcing the importance of marine-derived long‑chain omega‑3s in dietary planning [20,21,22].

Supplementation Strategy

For individuals who consume little or no fatty fish, or for those with persistently low omega‑3 index values, supplementation with EPA+DHA is an evidence‑based adjunct to dietary modification. Numerous expert bodies recommend a minimum of approximately 250–500 mg/day of combined EPA and DHA for general cardiovascular maintenance, with higher intakes often employed in secondary prevention or for achieving target omega‑3 index ranges. When selecting a supplement, several factors warrant consideration:

Purity and Safety

Long‑chain omega‑3 supplements should be sourced from manufacturers that provide third‑party testing for heavy metals, persistent organic pollutants, and oxidation markers, particularly given the susceptibility of polyunsaturated fatty acids to peroxidation. Regulatory reviews indicate that supplemental intakes of EPA+DHA up to about 5 g/day are generally safe in adults, but product quality is critical to minimize contaminant exposure and oxidative degradation [19,23,24].

EPA: DHA Profile

While there is no universally mandated EPA:DHA ratio, a relatively balanced composition (e.g., near 1:1) is often favoured in preventive and longevity‑oriented practice to simultaneously support cardiovascular, anti‑inflammatory, and neurocognitive pathways, rather than heavily privileging one physiological domain. Preparations markedly skewed toward EPA or DHA may be appropriate for specific indications but may not provide the broad, multimodal benefits sought in general health and aging interventions [19,23,24].

Source and Sustainability

Algae‑derived EPA/DHA preparations have emerged as a viable and environmentally sustainable alternative to fish oil. Randomized, double‑blind trials demonstrate that microalgal oils provide plasma phospholipid EPA and DHA bioavailability that is statistically non‑inferior to fish oil when matched for dose, indicating that algal sources can effectively raise circulating omega‑3 levels. In addition, algal cultivation in controlled environments can reduce exposure to marine contaminants and overfishing pressures, aligning omega‑3 supplementation with both safety and sustainability objectives [25].

Collectively, a “food first, then supplement” approach, prioritizing regular fatty fish intake and complementing it with high‑quality EPA+DHA products when necessary, offers a practical framework to achieve omega‑3 intakes associated with improved cardiometabolic, neurocognitive, and longevity outcomes

Public Health Perspective

Widespread suboptimal omega‑3 status has emerged as a significant population‑level concern with implications for the burden of cardiovascular and other chronic non‑communicable diseases. Global mapping studies of red blood cell (RBC) EPA+DHA indicate that large segments of North America, Europe, the Middle East, Southeast Asia, and Africa fall into the “low” (4–6%) or “very low” (≤4%) omega‑3 index categories, ranges that have been associated with increased risk of coronary heart disease (CHD) and all‑cause mortality. In contrast, only select regions with high habitual marine food intake, such as parts of Japan and Scandinavia, consistently achieve omega‑3 index values ≥8%, corresponding to the putatively cardioprotective range [26,27,28].

Within this context, the omega‑3 index, defined as the sum of EPA and DHA in erythrocyte membranes expressed as a percentage of total fatty acids, has been proposed as a clinically useful biomarker that bridges nutritional exposure and hard outcomes. The omega‑3 index fulfils key criteria for a cardiovascular risk factor, including robust epidemiologic associations with CHD mortality, plausible biological mechanisms, assay reproducibility, independence from traditional risk factors, and modifiability through diet and supplementation. Prospective and case–control data suggest that an omega‑3 index ≥8% is associated with substantially lower risk of fatal CHD, whereas values ≤4% confer the highest risk, with graded relationships across intermediate ranges [1,6,7,29,30].

From a public health and preventive medicine perspective, incorporating omega‑3 index testing into routine risk assessment could enhance stratification beyond conventional biomarkers such as LDL‑cholesterol, C‑reactive protein, or even smoking status, with some analyses indicating comparable predictive power for total mortality. Because omega‑3 status is readily modifiable via targeted dietary and supplementation strategies, systematic identification and correction of low omega‑3 index values offers a low‑cost, scalable intervention that aligns with contemporary models of precision prevention and longevity medicine [19,29,30].

Conclusion

Longevity is not a result of a single, dramatic intervention but rather a consequence of sustained optimization of multiple, modest yet impactful factors. Among these, nutritional adequacy particularly of essential fatty acids plays a critical role in maintaining systemic homeostasis and mitigating the biological processes that underlie chronic disease progression.

Insufficient omega‑3 polyunsaturated fatty acid intake represents one of the most modifiable and under‑recognized determinants of all‑ causing mortality and cardiometabolic dysfunction. Evidence consistently demonstrates that adequate levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) confer benefits across key domains of human physiology, including cardiovascular integrity, neurocognitive performance, and inflammatory regulation.

Optimization of omega‑3 status, achieved through a diet rich in marine‑based sources or through supplementation with purified and balanced EPA/DHA formulations, constitutes a practical and evidence‑supported strategy within preventive and longevity medicine. Addressing this subtle yet pervasive nutritional gap may therefore represent a fundamental step toward extending both lifespan and health span, reinforcing the notion that small, consistent interventions can yield substantial long‑term benefits for human health.

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