Omega-3 supplementation linked to lower Alzheimer's disease risk
The omega-3 fatty acids DHA and EPA are known to influence brain and cardiovascular health, and recent research suggests maintaining sufficient omega-3 levels contributes to longevity.1
Related: Want to live longer? Watch your omega-3 levels
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Blood n-3 fatty acid levels and total and cause-specific mortality from 17 prospective studies
Because DHA and EPA are concentrated in brain cell membranes, these fatty acids have been investigated for their effects on brain health.2 The available evidence suggests that DHA is more important for cognitive functions (such as learning and memory), whereas EPA is more important for regulation of mood.3-6
Related: Natural remedies for anxiety and depression
Sources:
The Importance of Marine Omega-3s for Brain Development and the Prevention and Treatment of Behavior, Mood, and Other Brain Disorders
Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA
A new study investigated both omega-3 intake and blood omega-3 levels in 1135 older adults (average age 73) who did not have dementia at the start of the study and followed them for six years. Participants who reported they had been taking omega-3 supplements had a 64% lower risk of developing Alzheimer’s disease than those who did not take supplements.
In addition to the data from these participants, the researchers also conducted a meta-analysis of 48 studies on a total of more than 103,000 participants. Overall, a high omega-3 intake, especially DHA, was associated with a 20% lower risk of cognitive decline or dementia. The researchers also performed a dose-response analysis, which found that every additional 100 mg of omega-3 DHA or EPA intake daily was associated with a lower risk of cognitive decline of about 8-10%. Higher levels of DHA and EPA in the blood were also linked to lower risk of cognitive decline.7
Previous studies have suggested that older adults with lower DHA and EPA status have MRI evidence of accelerated brain aging or a higher risk of dementia.8-11 Specifically, it appears an omega-3 index (a measure of EPA and DHA in red blood cells) below approximately 5-6% is associated with greater risk of reduced brain volume, other MRI markers of accelerated brain aging.9,12,13
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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
Defining the Optimal Target Population for Trials of Polyunsaturated Fatty Acid Supplementation Using the Erythrocyte Omega-3 Index: A Step Towards Personalized Prevention of Cognitive Decline?
Cognitive Impairment Is Associated with a Low Omega-3 Index in the Elderly: Results from the KORA-Age Study
It’s important to note here that omega-3 fatty acids are important nutrients for healthy brain function all throughout life, not just for older adults. Maintaining healthy omega-3 levels starting from fetal and childhood brain development could help prevent the brain aging that is associated with low DHA and EPA status in older age.
Related: How omega-3 fatty acids support brain health
Also important is that low omega-3 levels alone aren’t responsible for the development of Alzheimer's disease. Most risk factors for Alzheimer’s and other types of dementia are modifiable and many are diet-related, such as obesity, type 2 diabetes, hypertension, and alcohol consumption.14 The excess animal products, high saturated fat intake, processed foods, low micronutrient and phytochemical intake, and low omega-3 intake typical of the standard American diet (SAD), inflammation and oxidative stress (due to a poor diet), and other lifestyle factors such as low physical activity all contribute to dementia risk.14-17
Sources:
Dementia prevention, intervention, and care
Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions
Inflammation as a central mechanism in Alzheimer's disease
Low omega-3 intake is typical in modern diets, the ALA in flax, chia, and hemp seed and walnuts is not efficiently converted to DHA and EPA in many people, and research has confirmed that vegans tend to have a low omega-3 index.18 It is only a small amount of our population who are healthful-eating, non-fish eating and non-DHA-supplementing individuals, where a low omega-3 index becomes a predominant cause of dementia. That is why these studies do not show an even larger degree of protection and why the argument that vegans or vegetarians do not have more dementia than SAD eaters is a faulty excuse to accept a low omega-3 index. The facts are that healthful-eating vegans, whose only risk factor is low omega-3 index are those who will most strongly benefit from DHA supplementation.
Consuming pre-formed DHA and EPA is the most reliable way to increase blood omega-3 levels,18-21 and fish is an unfavorable source of DHA and EPA due to microplastics and other pollutants.22,23 I recommend taking an algae-derived DHA and EPA supplement, and testing omega-3 index every few years to confirm a level above 6% (I have recently increased my recommendation from 5% to 6% due to corroborative evidence of several recent studies on omega-3 index).
Shop: DHA+EPA Purity
Shop: Omega-3 Index Test
Sources:
Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega-3 fatty acid supplement
A Cross-Sectional Comparison of the Whole Blood Fatty Acid Profile and Omega-3 Index of Male Vegan and Omnivorous Endurance Athletes
Office of Dietary Supplements, National Institutes of Health. Omega-3 Fatty Acids
Distribution, interconversion, and dose response of n-3 fatty acids in humans
Microplastic Contamination of Seafood Intended for Human Consumption: A Systematic Review and Meta-Analysis
Global assessment of organic contaminants in farmed salmon