Supplement
Essential fatty acids are omega-3 and omega-6 fats the body cannot make, so they come from food, where they build cell membranes and feed signaling molecules involved in inflammation. People most often look at them for dry eye, and reviews of clinical studies found steadier tear film and eased symptoms, though the evidence is limited. Those were narrative reviews, not large trials, and results for ADHD were small and inconsistent.
Sources: PMID 20031476; PMID 20105404
- Updated
- How we grade
- 18 studies cited
- Best evidence
- Grade C
- Conditions studied
- 5
- Outcomes
- 12
- Graded outcomes
- 0039
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cardiovascular Risk Markers Reviews and mechanistic studies suggest that EFAs may function as endogenous HMG-CoA reductase inhibitors, ACE enzyme inhibitors, and anti-arrhythmic agents. Combined omega-3 and omega-6 supplementation improved blood rheology markers in small human trials, supporting a 'polypill' hypothesis for cardiovascular protection. | Improves (the measure goes down) | Moderate effect | 5 studies | |||
Studies that measured cardiovascular risk markers
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General
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Dry Eye Symptoms Two narrative reviews synthesized evidence from multiple clinical studies suggesting that essential fatty acid supplementation (both omega-3 and omega-6, particularly GLA and EPA/DHA) can improve tear film stability, reduce ocular surface inflammation, and alleviate dry eye symptoms. | Improves (the measure goes down) | Moderate effect | 4 studies | |||
| Tardive Dyskinesia Symptoms Two reviews examined the relationship between essential fatty acid status and tardive dyskinesia in schizophrenia patients, reporting that EFA deficits are common in these patients and that supplementation may have modest therapeutic potential, though controlled trial data remain limited. | Improves (the measure goes down) | Small effect | 4 studies | |||
| Infant Visual Development A clinical study in malnourished nursing infants found that dietary long-chain EFA supplementation improved visual evoked potential responses, and separate research confirmed that preterm infants have lower EFA status in umbilical vessel walls compared to full-term infants. | Improves (the measure goes up) | Moderate effect | 4 studies | 60 people | ||
Studies that measured infant visual development
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| EFA Deficiency in GI Disorders Clinical studies found a high prevalence of essential fatty acid deficiency in patients with chronic gastrointestinal disorders and cystic fibrosis, suggesting that targeted EFA supplementation may correct biochemical deficiency markers in these populations. | Changes; see studies | Moderate effect | 4 studies | 80 people | ||
Studies that measured efa deficiency in gi disorders
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| Depression Risk A narrative review linked low essential fatty acid intake (particularly omega-3 deficiency during caloric restriction and dieting) to increased risk of depression, noting that EFA-depleted diets may impair serotonergic neurotransmission. | Improves (the measure goes down) | Small effect | 3 studies | |||
| Multiple Sclerosis Symptoms A clinical trial found that co-supplementation with hemp seed and evening primrose oils (providing balanced omega-3 and omega-6 EFAs) alongside a hot-nature diet showed immunomodulatory and therapeutic effects in multiple sclerosis patients, including reduced relapse rates. | Improves (the measure goes down) | Moderate effect | 3 studies | 100 people | ||
| Atopic Dermatitis Symptoms A small randomized crossover trial found that dietary hempseed oil, rich in both omega-3 and omega-6 EFAs, improved skin dryness, itchiness, and reduced the use of dermal medications in patients with atopic dermatitis over 8 weeks. | Improves (the measure goes down) | Moderate effect | 2 studies | 20 people | ||
Attention Deficit Hyperactivity Disorder (ADHD)
- ADHD Symptoms: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| ADHD Symptoms A systematic review of clinical trials found that children with ADHD tend to have lower EFA levels, and some supplementation trials showed modest improvements in ADHD-related symptoms, though results were inconsistent across studies and effect sizes were generally small. | Improves (the measure goes down) | Small effect | 3 studies | 400 people | ||
Cardiovascular Health
- White Blood Cell Aggregation: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| White Blood Cell Aggregation A small clinical trial in healthy volunteers found that dietary supplementation with combined omega-3 and omega-6 fatty acids reduced induced white blood cell aggregation, suggesting improved microvascular flow properties. | Improves (the measure goes up) | Small effect | 3 studies | 20 people | ||
Studies that measured white blood cell aggregation | ||||||
Blood Health
- Red Blood Cell Rheology: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Red Blood Cell Rheology A small human trial found that combined omega-3 and omega-6 EFA supplementation improved red blood cell deformability and rheological properties, which may support microcirculation. | Improves (the measure goes up) | Small effect | 3 studies | 20 people | ||
Bone Health
- Bone Mineral Density: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Bone Mineral Density In a rat model, the ratio of n-6 to n-3 essential fatty acids significantly affected calcium balance and bone parameters, with lower n-6/n-3 ratios associated with improved calcium absorption and bone mineral content. | Improves (the measure goes up) | Small effect | 3 studies | |||
Key findings
- Cardiovascular Risk MarkersImproves (the measure goes down)
- Dry Eye SymptomsImproves (the measure goes down)
- ADHD SymptomsImproves (the measure goes down)
Safety notes in the studies
- A narrative review linked low essential fatty acid intake (particularly omega-3 deficiency during caloric restriction and dieting) to increased risk of depression, noting that EFA-depleted diets may impair serotonergic neurotransmission.
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- Grade C
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Studies cited
18 studies from PubMed
- Immunomodulatory and therapeutic effects of Hot-nature diet and co-supplemented hemp seed, evening primrose oils intervention in multiple sclerosis patients.
- Perinatal programming of murine immune responses by polyunsaturated fatty acids.
- Essential fatty acids for dry eye: A review.
- Essential fatty acids in the treatment of dry eye.
- Essential fatty acids and attention-deficit-hyperactivity disorder: a systematic review.
- Essential fatty acids and their metabolites could function as endogenous HMG-CoA reductase and ACE enzyme inhibitors, anti-arrhythmic, anti-hypertensive, anti-atherosclerotic, anti-inflammatory, cytoprotective, and cardioprotective molecules.
- Do polyunsaturated fatty acids behave like an endogenous "polypill"?
- Tardive dyskinesia and essential fatty acids.
- Essential fatty acids, DHA and human brain.
- Dieting, essential fatty acid intake, and depression.
- Dietary long-chain fatty acids and visual response in malnourished nursing infants.
- The beneficial effects of omega-3 and omega-6 essential fatty acid supplementation on red blood cell rheology.
- Dietary supplementation with omega 3 and omega 6 fatty acids reduces induced white blood cell aggregation in healthy volunteers.
- Schizophrenia, tardive dyskinesia and essential fatty acids.
- Prevalence of essential fatty acid deficiency in patients with chronic gastrointestinal disorders.
- Essential fatty acid deficiency and predisposition to lung disease in cystic fibrosis.
- The effect of different n-6/n-3 essential fatty acid ratios on calcium balance and bone in rats.
- Comparison between the essential fatty acid status of preterm and full-term infants, measured in umbilical vessel walls.