Why Vegans Need DHA and EPA
Discover why maintaining an adequate level of omega-3 fatty acids is essential, especially for vegans and vegetarians, for brain health and longevity.
As the research on omega-3 fatty acids evolves, so does our understanding of its impact on health. In addition to its benefits for brain health and inflammation regulation, higher omega-3 status or omega-3 supplementation has now been linked to:
- reduced risk of all-cause mortality
- an enhanced antioxidant response
- maintaining muscle mass and exercise performance
- slower biological aging.1-7
Related: Want to live longer? Watch your omega-3 levels
Blood n-3 fatty acid levels and total and cause-specific mortality from 17 prospective studies
What do omega-3 fatty acids do?
In addition to their overall health benefits, EPA and DHA are especially crucial for the brain, eyes, heart, and inflammatory response.
DHA is a major structural fat in the human brain, making up about a quarter of all fatty acids in the cerebral cortex. Since DHA levels tend to decline with age, maintaining adequate DHA levels is important for healthy brain aging.5, 8, 9
Most of the effects of EPA and DHA stem from their incorporation into our cell membranes, where they influence signals coming into the cell, the cell’s response to stresses, gene expression, and inflammation.5, 8, 9
Related: How omega-3 fatty acids support brain health
Regulating inflammation, vision, heart health and mood
In the brain, DHA supports neuroplasticity, neurotransmitter function, membrane stability, inflammatory balance, and the clearance of harmful proteins such as amyloid beta. DHA is also highly concentrated in the outer segments of rod photoreceptors in the retina, where it contributes to healthy vision.
EPA in the brain is involved in regulating mood as well as inflammation. Low omega-3 status, especially EPA, has been linked to higher risk of depression. Long-chain omega-3s also help maintain cardiovascular health, influencing heart rhythm, blood pressure, triglyceride levels, and endothelial function, along with inflammation.5, 8-11
Related: Natural remedies for anxiety and depression
Very long-chain n-3 fatty acids and human health: fact, fiction and the future
Omega-3 fatty acids and major depression: a Mendelian randomization study
Marine Omega-3 (N-3) Fatty Acids for Cardiovascular Health: An Update for 2020
Preventing dementia and loss of brain volume
A 2023 meta-analysis of 48 studies found a high omega-3 intake, especially of DHA, was associated with a 20% lower risk of cognitive decline or dementia.
Each additional 100 mg of omega-3 DHA or EPA intake daily was associated with an 8-10% lower risk of cognitive decline, and higher blood levels of omega-3 were also linked to lower risk of cognitive decline.12
Related: Omega-3 supplementation linked to lower Alzheimer's disease risk
Lower omega-3 status in older adults is also linked to evidence of accelerated brain aging in MRI studies, such as reduced brain volume, amyloid beta accumulation, and white matter abnormalities.13-20 Small cognitive decrements associated with lower omega-3 status have been observed even in young adults with overall normal cognitive function.21
In a new study published in 2025, researchers recruited middle-aged adults (ages 45-74) with no cognitive impairment who were at a high risk of Alzheimer's disease (AD). The scientists found that higher DHA status was associated with improved cognitive performance over the duration of the study (about three years).
Notably, the association of DHA status with cognitive function was stronger than the associations for “classical risk factors,” such as age, sex, years of education, and genetics (APOEε4).22
Sources:
Blood polyunsaturated omega-3 fatty acids, brain atrophy, cognitive decline, and dementia risk
Red blood cell ω-3 status and longitudinal cognition in individuals at risk of Alzheimer disease
Supporting brain health in vegans with long life expectancy
The Adventist Health Study 2 provides some insight into why omega-3 adequacy is critical for people on a health-promoting, plant-based diet, whose overall risk for cognitive decline and dementia is otherwise low.
Among 88,400 participants, followed over about 11 years, compared to non-vegetarians, vegetarians and vegans had a lower risk of death from all causes, heart disease, infectious diseases, kidney failure, or diabetes. However, there were specific causes of death – notably all neurological conditions – where older vegetarians and vegans (age 85 or older) had higher rates of death than older non-vegetarians: a 17% higher risk of death from stroke, 13% higher risk of death from dementia, and 37% higher risk of death from Parkinson’s disease.23
Seventh Day Adventists generally have higher-quality diets than the typical American, and the vegetarians and vegans in the study were on average better educated, exercised more, had lower BMI and calorie intake, and were less likely to smoke or drink alcohol than omnivores.23
Could a vegetarian or vegan diet increase the risk of stroke, dementia, and Parkinson’s disease?
One possible reason for the higher risk of neurologic-associated death compared to omnivores at older ages is a low level of DHA and EPA intake. Although vitamin B12 deficiency is another potential cause, most vegans in the study population took B12 supplements and had adequate serum B12.23 However, vegetarian and vegan participants in the Adventist Health Study 2 not taking EPA and DHA supplements did have low omega-3 status.24
Related studies have come to different conclusions on whether vegetarians and vegans are more or less likely to develop depression than omnivores.25
Plant foods are beneficial for brain health and mood in part because of their polyphenols, carotenoids, and antioxidant vitamins.26-28 Although vegetarians and vegans often consume more vegetables and other high-antioxidant foods, they are at risk of low vitamin B12 and omega-3 levels if not taking supplements. Some findings of an increased risk of depression in vegans could have been due to insufficiencies in omega-3s.
Association between vegetarian and vegan diets and depression: A systematic review
Natural products, micronutrients, and nutraceuticals for the treatment of depression: A short review
Assuming a diet that excludes animal products is
automatically neuroprotective without proactive, targeted nutrient adequacy is
a dangerous blind spot. The 37% elevated risk of Parkinson’s disease (PD)
observed in the vegan cohort of the AHS-2 is a textbook example of this
vulnerability. When combined with the underlying neurobiology, the mechanistic
link between low DHA levels/omega-3 index, environmental neurotoxicity, and neurodegeneration
becomes undeniable.
Parkinson’s disease, pesticide exposure, and omega-3 intake
The Agricultural Health Study (AHS), run by the USDA, collects data on the diet, lifestyle habits, pesticides used, and health of the workers who apply pesticides to crops. It collects the same data on the workers’ spouses.
A study within the AHS investigated dietary fats, pesticide use, and Parkinson’s disease risk, and found that risk of PD was lower in participants with higher intake of total omega-3 fatty acids and ALA, the omega-3 found in flax seeds, chia seeds, hemp seeds, and walnuts.
They also found the risk of PD associated with exposure to the pesticides paraquat and rotenone was elevated in specific groups, notably: participants with high saturated fat intake, participants with low total polyunsaturated fat intake, those with low total omega-3 intake (omega-3s are polyunsaturated fats), and those with low omega-3 ALA intake.29
How different types of fats influence the effects of toxins like pesticides
Paraquat, rotenone, and other pesticides cause neurotoxicity partly by oxidative stress and inflammation. High saturated fat intake promotes oxidative stress and inflammation. In contrast, omega-3 fatty acids dampen the inflammatory response. They promote anti-inflammatory and inflammation-resolving processes, and are important for neurotransmission and other brain functions.29
Randomized controlled trials (RCTs) of omega-3 supplementation (ALA or DHA and EPA) in patients with PD have demonstrated a slowed progression of PD.30 In one 30-month trial on DHA and EPA, on average the participants in the placebo group required an increase in their dose of levodopa, while the supplementation group didn’t.31
Sources:
Dietary fat intake, pesticide use, and Parkinson's disease
Higher omega-3 levels linked to improved antioxidant response and protection from toxins
Related to omega-3 fatty acids’ potential to reduce the dangerous effects of pesticides, they also improve antioxidant capacity. This leads to a more robust defense against oxidative stress.
A meta-analysis of 38 RCTs of omega-3 fatty acid supplementation found:
- 50% increase in total antioxidant capacity
- 73% increase in the antioxidant enzyme glutathione peroxidase,
- 42% decrease in malondialdehyde, a marker of lipid peroxidation, in supplementation compared to placebo groups.4
This suggests an increase in resistance to oxidative damage, and other stressors too, since our system for antioxidant defenses is the same one that provides resilience to toxins.
Another study using MRI to measure the integrity of the blood-brain barrier in older adults found that higher omega-3 levels were linked to greater blood-brain barrier integrity. The blood-brain barrier prevents harmful substances from entering the brain.32
Everyday life exposes humans to ubiquitous
neurotoxins—including particulate air pollutants, paraquat, rotenone, other
pesticides, PCBs, and heavy metals. These substances have neurotoxic effects
through oxidative stress, mitochondrial dysfunction, and neuroinflammation.
Several have been shown to impair energy production by inhibiting complex 1 of
the electron transport chain in mitochondria.33-35
Omega-3 fatty acids are associated with blood-brain barrier integrity in a healthy aging population
Oxidative stress is a driver of dementia and Parkinson's disease
Oxidative stress is central to several different factors involved in Alzheimer’s disease pathogenesis, including beta-amyloid plaques, tau hyperphosphorylation, neuroinflammation, and neuron death.36
Neurons overall have a high energy demand, and the
dopaminergic neurons in the substantia nigra pars compacta (SNpc) have higher
metabolic rates than most other neurons. These neurons are involved in regulating
motor function, and progressive loss of these neurons is a key pathologic
feature of Parkinson’s disease. SNpc dopaminergic neurons are more vulnerable
to oxidative stress than other types of brain cells, likely because of their
high demand for energy, in part due to their extensively branched structure.37 Their large dopamine and iron content,
as well as higher levels of vascularization and lower intracellular glutathione
levels compared to other brain regions are other possible reasons why these
neurons are uniquely vulnerable to oxidative stress and toxins.38, 39
When a brain has a robust omega-3 index (7% or higher) and adequate DHA stores, it possesses the structural membrane resilience, antioxidant capacity, and pro-resolving mediator signaling necessary to buffer oxidative stress and repair neuronal damage due to everyday exposures.
In a long-term vegan with a critically low omega-3 index (often 4% due to the inefficient conversion of ALA), the brain is stripped of its primary defense, allowing environmental toxicants to trigger irreversible neurodegenerative cascades.
The key neuroprotective mechanisms of DHA
DHA is not merely a fat that is found in the brain, it is a fat that’s crucial for brain tissue structure and function. DHA is the most common polyunsaturated fat in the human brain, making up roughly 30-40% of the cell membrane phospholipids in the gray matter of the cerebral cortex and photoreceptors of the retina, and about 25% of total fatty acids in the human cerebral cortex.5, 40, 41
Membrane integrity and function: DHA maintains fluidity in the cell membranes of neurons, keeping them flexible and responsive, so that proteins in the membrane, such as receptors and ion channels, can function properly. This supports effective signaling by neurotransmitters including dopamine.42
Protection from oxidative stress: As described above, DHA supplementation increased markers of antioxidant capacity in human studies, suggesting increased resistance to oxidative damage, likely by upregulating the body’s natural antioxidants.4
Protection from neuroinflammation – synthesis of pro-resolving mediators: DHA is the precursor to neuroprotectin D1 (NPD1), a potent inflammation-resolving lipid mediator. NPD1 suppresses neuroinflammation in microglia (the immune cells that reside in the central nervous system), upregulates anti-apoptotic proteins to promote neuron survival, and inhibits inflammatory cytokine cascades triggered by environmental toxins. Resolvins and maresins derived from EPA and DHA are additional neuroprotective mediators with anti-inflammatory and inflammation-resolving effects.43, 44
Protection from pathogenic changes in the brain: Studies in animals suggest that adequate DHA helps to increase amyloid beta clearance and limit tau hyperphosphorylation, processes involved in Alzheimer’s disease.41, 45
Blood-brain barrier integrity: The blood-brain
barrier is a specialized layer of endothelial cells that regulates which
substances from the bloodstream can enter the brain, protecting the brain from
toxins. As described above, an MRI study showed older adults with higher
omega-3 levels had greater blood-brain barrier integrity.32
How much ALA can we convert to EPA and DHA?
Alpha-linolenic acid (ALA) from walnuts and flax, chia, and hemp seeds can take two paths: it can be broken down to produce energy or recycle its component carbons, or it can enter the pathway leading to synthesis of EPA and DHA.
Genetics, sex, and individual dietary factors influence how much ALA gets converted to EPA and then DHA. “Desaturase” and “elongase” enzymes catalyze different steps of the synthesis of long-chain omega-3 (EPA and DHA) and omega-6 fatty acids from ALA and the essential omega-6 LA.
Genetics: There are several genetic alterations that reduce the activity of the desaturase and elongase enzymes, leading to lower EPA and/or DHA levels.
Sex differences: Females tend to have higher DHA levels than males, on average approximately 15% higher, in part due to differences in the amount of ALA broken down for energy, sex-related differences in fat tissue, and effects of sex hormones on the chemical reactions that produce EPA and DHA. Research suggests that estrogen and progesterone promote synthesis of DHA from ALA, whereas testosterone may inhibit it.
Diet: The composition of your diet also affects how much ALA you can convert to EPA and DHA. Since omega-3 and omega-6 fatty acids require the same enzymes for desaturation and elongation, a higher intake of omega-6 LA could reduce elongation of ALA.
Many sources of ALA are also high in omega-6 linoleic acid (LA). Of ALA-rich plant foods, the highest ratio of ALA to omega-6 is found in flax and chia seeds, followed by hemp seeds and walnuts. There is also some evidence that high intake of sugars may interfere with the metabolism of omega-3 fatty acids. Meals high in fiber, although healthful, can limit how much fat – including ALA – is absorbed in the gastrointestinal tract.8
Studies in humans using labeled ALA estimated that less than
1% of ALA is converted to DHA.46
Metabolism and functional effects of plant-derived omega-3 fatty acids in humans
ALA (from flax, chia, hemp, and walnuts) alone is not enough for most people to reach a sufficient omega-3 index
No official definitions of insufficiency or deficiency based on blood levels of EPA and DHA have yet been established. However, the omega-3 index, a measurement of the percent of total fatty acids in red blood cell membranes as EPA+DHA, is a useful indicator that correlates with cardiovascular and brain health measures.15,47
Regardless of estimates of ALA conversion to EPA and DHA, and relative differences in conversion efficiency between individuals, studies in humans have consistently shown that ALA supplementation does not increase omega-3 index.48 However, supplementation with algae-derived, pre-formed EPA and DHA does increase omega-3 index.48,49
ALA was given in doses of 6-8 grams/day in these studies. For reference, flax seeds contain about 2 grams ALA per tablespoon, and walnuts contain about 2.5 grams ALA per ounce. The recommended daily allowance (RDA) for ALA ranges from 1.1 to 1.6 grams for adults, depending on sex and life stage.
A 2014 study of vegans not taking DHA and EPA supplements found that most had an omega-3 index considered insufficient. The average omega-3 index of the vegans in the study was 3.7%, 64% had levels lower than 4%, and 27 percent had levels lower than 3%. The average ALA intake was 3.4 grams/day, more than double the RDA.50
Other observational studies, including the Adventist Health Study 2, have confirmed low omega-3 index in vegans, usually finding an average of approximately 4%.24,51 Also similarly, intakes of alpha-linolenic acid (ALA; the omega-3 in flax, chia, and hemp seeds and walnuts) and linoleic acid (LA; an omega-6 fatty acid) were not associated with omega-3 index in Adventist Health Study 2 participants.
How much EPA and DHA do we need? And what omega-3 index should we aim for?
Large population studies risk have suggested that a high risk of heart disease is associated with an omega-3 index less than 4%, and the lowest risk of heart disease when omega-3 index is greater than 8%.52 Based on studies of brain volume and cognitive function in older adults, an omega-3 index of at least 6% is likely required for healthy brain aging.14,15,17-19 A recent study found participants in the highest fifth of omega-3 index (higher than 6.8%) at age 65 on average gained 4.74 years of life compared to the lowest fifth (lower than 4.2%).53
An omega-3 index of 8% may not be attainable with reasonable levels of supplementation for many people. High doses of omega-3 fatty acids (more than 1 gram) are likely only warranted if treating a medical condition, because high doses (especially of EPA) have been associated with atrial fibrillation.54
My goal in recommending supplementation is to ensure people have enough EPA and DHA to keep their brains healthy for life, even if their conversion rate is somewhat low. Maintaining healthy omega-3 levels now could help prevent the brain aging associated with low DHA and EPA status in older age.
There are many factors that contribute to Alzheimer’s disease and other types of dementia, and many are modifiable, such as obesity, type 2 diabetes, hypertension, and alcohol intake.55 For Parkinson’s disease, dairy intake and type 2 diabetes are modifiable risk factors, as well as pesticide exposure.56
However, for those few who are eating healthfully and not eating fish, a low omega-3 index may be their one modifiable risk factor for neurodegenerative diseases. This population could benefit dramatically in quality of life in their later years from supplementation.
Sources:
Red blood cell omega-3 fatty acid levels and markers of accelerated brain aging
Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes: WHIMS-MRI study
Some argue that lower omega-3 index in vegans simply reflect
a natural, healthy baseline rather than an insufficiency. However, when lower omega-3
levels consistently correlate with measurable structural consequences—such as
reduced hippocampal volume, white matter hyperintensities, and increased
late-life neurological mortality—that lower level represents a functional
vulnerability over a long lifespan, not an optimal adaptation. The
epidemiological signal in AHS-2 is a stark reminder that minimizing or
eliminating animal foods is only step one; optimizing nutrient adequacy and human
biochemistry is step two. Without ensuring preformed, clean DHA (via
unadulterated algal oils), optimizing B12 status, and maintaining high
antioxidant phytonutrient density, a plant-based diet can inadvertently swap
cardiovascular risk for neurodegenerative vulnerability.
My recommendations
- Supplement with EPA and DHA to reach an omega-3 index of 7%-9%
- Have one tablespoon flaxseed and one tablespoon chia seed daily
- Make flax, chia, hemp, and walnuts at least half of your daily nuts and seeds