Research uncovering the various roles of omega-3 fatty acids in human health continues to grow and evolve. One focus area that has caught the interest of the global health community is omega-3s’ potential role in brain health and function.
While omega-3s act through various mechanisms, one way omega-3s may support cognitive function is by modulating brain-derived neurotrophic factor (BDNF). This article will explore the relationship between omega-3 fatty acids and BDNF and review who may benefit from increasing omega-3 intake.
Omega-3s and Brain Health
Omega-3 fatty acids, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA) are all essential for brain health and function. The brain is the fattiest organ in the body, with roughly 60% of its dry weight coming from fat. Of the different omega-3 fats, DHA is the dominant one, comprising close to 40% of the total fatty acids in the brain. DHA is also abundant in the central nervous system, where it accumulates during fetal development. DHA can cross the blood-brain barrier through passive diffusion and increasing omega-3 intake in the diet increases levels in the brain.
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A systematic review of randomized clinical trials published in 2022 identified various studies that found omega-3 supplementation improved mental performance, blood flow and circulation to the brain, and early memory and learning deficiencies related to cognitive aging. Another review published in 2023 reported that daily intake of EPA and DHA over 30 months slowed cognitive aging by 2.5 years in cognitively healthy individuals with coronary artery disease. Omega-3 fats play vital roles that may impact brain function and cognition, such as decreasing inflammation, preserving and protecting neurons, altering membrane fluidity, and increasing neurotransmission. More recently, the impact of omega-3s on BDNF has gained attention.
What is BDNF?
BDNF is one type of neurotrophin that supports survival, differentiation, and regulation of neurons in the brain and central nervous system. Neurotrophins, also called neurotrophic factors, are a family of small proteins that regulate nervous system development, maintenance, and function. While there is still plenty to learn about BDNF, it is one of the most extensively studied neurotrophins in the mammalian brain.
BDNF has been found to possess diverse functions across brain and central nervous system structures. It plays roles in the growth and differentiation of neurons, neural plasticity, dendritic branching, and neuroprotection.
BDNF levels have also been associated with brain-associated illness. For example, deficits in BDNF are reported to contribute to the evolution of Alzheimer’s disease, depression, anxiety disorders, and other brain and mental health-related disorders. Furthermore, low BDNF can be a result of chronic stress, neuroinflammation, and oxidative stress. Low levels of BDNF attenuate the ability of neurons to handle difficulties and increase neuronal death. Therefore, the modulation of BDNF may present a promising approach to preventing and treating neurological and psychiatric disorders.
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Do Omega-3s impact BDNF?
Enriching brain omega-3s is beneficial for cognitive health and longevity. However, due to differences in study methodologies and varying doses and populations tested, studies assessing omega-3 effects on BDNF levels have been mixed.
Yet, Ziaei et al. published a 2023 systematic review and meta-analysis of randomized controlled studies that evaluated the effects of omega-3 fats on BDNF levels through a comparison of omega-3 supplementation versus placebo or no intervention. Twelve studies were included in the review, which incorporated 587 participants in total. The participants included a clinical population that comprised various health conditions, including coronary artery disease, type 2 diabetes, depression, schizophrenia, and severely injured patients who were vulnerable to post-traumatic stress disorder. The studies included interventions that lasted between 4-26 weeks and doses of omega-3s from 230-3750 mg/day.
A pooled analysis of the 12 studies revealed that supplementation with omega-3 fats effectively increased serum levels of BDNF compared to untreated counterparts. The authors also reported that the interventions that provided omega-3 fatty acid dosages exceeding 2000mg/day were more effective at increasing BDNF than an intake equal to or less.
Additionally, the effects of omega-3 appeared to be most significant in men, in those without psychological disorders, and younger individuals. Therefore, while individual studies may have conflicting results, likely due to variations in methodology, this systematic review indicates a relationship between omega-3 intake and BDNF levels.
Another study by Sugasini et al. used animal models to determine whether plasma BDNF might be used as a biomarker for brain DHA enrichment. The authors indicated that since there is convincing evidence that DHA increases the expression of BDNF, and since there is no direct way to measure levels of brain DHA, plasma BDNF levels may be a reliable marker for omega-3 levels in the brain. The researchers altered brain DHA levels in rats and mice. They found that increases in brain omega-3 levels positively correlated with increases in plasma BDNF.
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Who Might Benefit from Increasing Omega-3 Intake?
Individuals likely to benefit from increasing omega-3 intake are those whose current intake is insufficient. The only way to objectively know if your omega-3 intake is adequate is to test your omega-3 index.
The Omega-3 Index measures the amount of EPA and DHA in the red blood cell membranes and is expressed as a percentage. Evidence indicates that an Omega-3 Index of 8% or higher is associated with the most significant health outcomes. Anyone with an Omega-3 Index below that might benefit from increasing omega-3 intake. In their 2023 review, Ziaei et al. noted that dosages assigned in clinical trials when testing omega-3 outcomes should be based on an individual’s Omega-3 Index and omega-6/omega-3 ratio (instead of using fixed amounts for everyone).
Other populations that might benefit from increasing omega-3 intake include those with low BDNF levels, signs and symptoms of depression, those who are pregnant or breastfeeding, or those with cardiovascular health concerns.
Investigations have also found that lonely participants may benefit from omega-3 supplements. According to longitudinal studies, lonely people exhibit more significant decreases in episodic verbal memory than those less lonely. Omega-3s have been found to improve immediate verbal memory, indicating they might help lonely individuals struggling with mental deterioration over time.
Finally, the aging population might benefit from increased omega-3 intake. As people age, their food and fish consumption tends to decrease. Research shows that an increase in the Omega-3 Index can improve memory recall in elderly participants compared to a placebo.
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How do I Increase Omega-3 in my Diet?
Increasing the intake of omega-3s through whole foods would benefit health and wellness the most. Omega-3s can be found in high amounts in fish and other seafood options. Yet, fish and seafood are not always accessible or desirable options, especially for aging populations who often need it the most. In those cases, supplementation is a safe and effective alternative. Be sure to speak to your medical provider and read more about choosing a safe and appropriate supplement before heading to the supplement aisle.
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Summary
Evidence demonstrating the positive effects of omega-3 intake on brain health continues to grow. A recent literature review indicates that one mechanism through which omega-3s can impact brain health is through increasing levels of BDNF. While there are several populations, including those with low BDNF levels, that might benefit from increasing intake of omega-3 fats, the best way to know if sure if you need more is through testing your Omega-3 Index.
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While the Omega-3 Index is an excellent measure of long-term omega-3 intake, more research is required to determine the best method to assess brain DHA levels. However, based on the current evidence, if your Omega-3 Index is below 8%, you might benefit from increasing omega-3 intake through whole food or supplement sources. Be sure to speak with your healthcare provider before changing your diet or beginning a new supplement routine.
