Omega-3/6 ratio in brains predicted seniors’ memory and thinking status
Dementia is a fast-growing burden on families and public health budgets alike.
Alzheimer's disease is the most common kind, totaling about 70 percent of dementia diagnoses.
The risk for Alzheimer’s is partially related to genetics, with people who carry the APOE4 gene variant running the highest risk.
But it’s also clear that diet and exercise influence three things: the risk for developing Alzheimer’s and other forms of dementia, at what age symptoms appear, and the severity of those symptoms.
Much of the blame for fueling the growing epidemics of Alzheimer’s, heart disease, and diabetes belongs to the standard American diet’s excess of four things:
- Sugars and “white” starches
- Certain (not all) saturated fats
- Omega-6 fats from cheap vegetable oils
- Trans omega-6 fats from partially hydrogenated vegetable oils.
In excess, those diet factors promote key causes of those three major diseases: insulin resistance, oxidation of blood lipids, and silent, systemic inflammation.
And the results of a Canadian/Japanese clinical study support what many have suspected.
They add evidence that America’s extreme omega-3/6 fat intake imbalance raises people’s risks for dementia, including Alzheimer’s.
To learn more about that issue, see our “Out of Balance” video and these reports: Does Sugar Raise Alzheimer’s Risk?, Fructose Harms Brain Genes; Omega-3s Undo the Damage, Omega-3/6 Imbalance Impairs Brain-Mood Health, Omega-3/6 Imbalance May Blunt Babies’ Brains, Omega-3s Boost Infant Brains; Omega-6 and Trans Fats Hinder Them.
Clinical study links omega-3/6 imbalance to poor brain performance
The disturbing findings came from a small clinical study conducted by a Canadian/Japanese team (Andruchow ND et al. 2017).
The authors set the stage with this summary: “Evidence from several cross-sectional [epidemiological] studies indicates that an increase in [the proportion of] omega-6 to omega-3 fatty acids [in people’s diets] may negatively affect cognition in old age.”
Their study examined how the omega-3/6 intake ratio affects the hippocampus, a major seat of memory that's among the first brain structures affected by age. Atrophy (shrinkage) of the hippocampus has been definitively linked to cognitive decline.
They also wanted to see whether the participants’ omega-3/6 intake ratios predicted basic cognitive capacities like memory and thinking.
Given the results of prior epidemiological research, the Canadian/Japanese team suspected that people who consume fewer omega-6s relative to omega-3s would display better spatial memory and better thinking capacity.
They recruited 52 healthy older adults who completed a diet survey, took the Montreal Cognitive Assessment test (MoCA), and were asked to perform tasks designed to measure “navigational strategies” and the ability to remember three-dimensional spaces.
And the participants whose diets provided fewer omega-6s in relation to omega-3s were much more likely to display three advantages:
- Faster learning on virtual-navigation tasks
- Better cognitive performance (thinking) overall
- More accurate hippocampus-dependent spatial memory
The Canadian/Japanese team said these results may help explain why diet patterns with a lower omega-6/3 ratio — like the Mediterranean and related MIND diets — are associated with reduced risk of cognitive decline.
For more about research on the brain benefits of diets relatively low in omega-6s and high in omega-3s, see MIND Diet May Cut Alzheimer's Risk, Mediterranean Diet May Guard Thinking and Memory, Brain Aging Delayed by Mediterranean Diet, Med Diet and Low Blood Pressure May Deter Dementia, and Fast Food Diet May Raise Alzheimer's Risk, and Brain Benefits from Olive Oil?.
Several studies have found lower levels of omega-3 DHA in the brains and blood of people diagnosed with Alzheimer’s, suggesting that a lack of DHA makes people more vulnerable to the disease — and/or that the brain's attempts to heal itself deplete its cells' stores of DHA (Conquer JA et al. 2000; Cunnane SC et al. 2012; Cui Y et al. 2015).
And there’s a great deal of evidence suggesting that omega-3 DHA is an ally against Alzheimers' and other forms of dementia.
For example, see Omega-3s Seen to Ease Alzheimer's Symptoms, Omega-3 Displays More Alzheimer's-Deterring Effects, Omega-3 DHA May Help Avoid or Ease Alzheimer's, Alzheimer's News Points to Omega-3s' Promise, Omega-3s May Purge Alzheimer's Plaque, and Omega-3 May Prune Damaging Brain Plaque.
So it only makes sense to eat plenty of seafood, take fish oil, and cut back on cheap vegetable oils that are high in omega-6 fats: corn, soy, cottonseed, safflower, and sunflower.
Note: Look for "high-oleic" versions of sunflower and safflower oil, which are much lower in omega-6 fatty acids but high in oleic acid, the monounsaturated fat that predominates in olive oil.
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