Findings from a UK-Australia research collaboration found that cerebrovascular responsiveness (CVR) response to elevated carbon dioxide (CO2) levels in the blood increased in women taking a docosahexaenoic acid (DHA)-rich fish oil supplement.
Additional findings found no associated improvement of mood or cognition in either men or women.
“The lack of change in mood or cognition could have been due to inadequate intakes of either eicosapentaenoic acid (EPA) or DHA, too brief a period of supplementation or an inappropriate choice of participants for our study,” the study concluded.
“Despite a lack of change in mood or cognition outcomes, the present study adds to a growing number of studies suggesting that long-chain (LC) omega-3 PUFA supplementation can influence brain functions at least in part by enhancing cerebrovascular function, which may potentially delay future cognitive decline.”
Brain function and ageing
An ever-expanding range of potential health benefits has been credited to LC omega-3 PUFA containing EPA and DHA as distinct from the shorter chain length omega-3 PUFA containing inolenic acid.
While structural functions of omega-3 and omega-6 PUFA are crucial in early development, particularly of the nervous system, their regulatory functions are of critical importance in maintaining physiological homeostasis and counteracting chronic inflammation and other conditions.
Of these, effects on brain function are emerging as possibly the most important for an ageing population.
“DHA is the most common omega-3 fatty acid in the brain having a series of important effects preventing inflammatory brain cell death, which is the pathological basis for Alzheimer’s disease,” explained Dr Morten Bryhn, scientific advisor at Epax, a wholly owned subsidiary of Norwegian company Pelagia, who supplied the study with the omega-3 oil supplements.
“EPA being another marine omega-3 fatty acid is present in less amount in the brain, although enriched in arterial endothelium engaged in maintaining arterial tone and blood flow.”
In the study a team from Newcastle University and the University of Southern Queensland in Australia, enrolled 48 borderline hypertensives aged 40–85 years for a 20-week pilot trial.
Participants were required to consume four capsules of EPAX 1050 fish oil or a corn oil placebo, daily during this period.
Each EPAX capsule contained 400 milligrams (mg) DHA and 100 milligrams (mg) EPA, yielding a total dose of 2 grams (g) LC omega-3 PUFA per day. Placebo capsules contained corn oil.
Cerebrovascular function was assessed at baseline and after 20 weeks in 38 completers (19 on each supplement) at rest and whilst performing a number of cognitive tasks (neurovascular coupling).
The team found cerebrovascular responsiveness (CVR) to elevated levels of carbon dioxide in the blood (hypercapnia), increased 26% in women but no change in men.
In contrast, neurovascular coupling increased significantly in men only with these findings correlating with an increase of erythrocyte EPA.
“These preliminary observations indicate that LC omega-3 PUFA supplementation has the potential to enhance blood flow in the brain in response to both hypercapnic and cognitive stimuli,” the study said.
Increase in EPA erythrocyte levels
The team commented that improvement of CVR to the overall cognitive test battery correlated with increases in erythrocyte levels of EPA, not DHA.
“This is at odds with our hypothesis that DHA is the primary LC omega-3 PUFA which enhances cerebral endothelial function, improving blood flow globally and on demand in activated brain regions and thereby improving both mood and cognition.
“It would appear that the improvements in cerebral perfusion which we have observed following consumption of LC omega-3 PUFA are more likely to be attributable to increases in EPA than DHA.”
Dr Bryhn added that the report was important in “pointing to the fact that brain blood flow varies following stressful situations in daily life and that reduced flow may be counteracted by omega-3 fatty acids, in particular EPA”.
“About 30% of the heart minute volume is directed to the brain emphasising the negative impact of daily-life situations and arterial diseases restricting blood flow.
“Cerebral microinfarctions is common in the elderly leading to cognition defects with a prevalence only second to Alzheimer’s disease with a different pathology which may be halted by DHA.
“Regular intake of food supplements containing both omega-3 fatty acids may have the potential of preventing memory decline whether caused by restricted blood flow or inflammatory degeneration of brain cells.”
Published online: doi:10.3390/nu10101413
“Effects of Long Chain Omega-3 Polyunsaturated Fatty Acids on Brain Function in Mildly Hypertensive Older Adults.”
Authors: Peter Howe, Hamish Evans, Julia Kuszewski, Rachel Wong