Omega-3 fatty acids nutrients long thought to be helpful for neurological
health can cross the usually impenetrable blood-brain barrier and make their
way into the brain, a new study suggests.
The finding could have implications for the use of omega-3s as a treatment
for diseases such as Alzheimer's, the Swedish researchers said.
As published in the Journal of Internal Medicine, scientists at the
Karolinska Institute in Stockholm wanted to learn how far in the nervous system
omega-3 fatty acids might travel.
"Earlier population studies indicated that omega-3s can protect against
Alzheimer's disease, which makes it interesting to study the effects of dietary
supplements containing this group of fatty acids in patients who have already
developed the disease," study lead author Dr Yvonne Freund-Levi said in an
institute news release.
Key omega-3 fatty acid
The researchers said fatty acids accumulate naturally in the central nervous
system of the foetus during gestation, and "it has been assumed that these
acids are continually replaced throughout life."
But whether this happens and whether a person's diet makes a difference has
been unknown. One key question: do dietary fatty acids have the ability to
cross the brain's protective blood-brain barrier? This natural barrier shields
the brain from harmful chemicals found elsewhere in the body, the researchers
The issue is particularly important for Alzheimer's disease research,
because prior studies have shown that Alzheimer's patients have lower levels of
a key omega-3 fatty acid in the cerebrospinal fluid (the liquid that surrounds
the central nervous system).
In the six-month study, 18 patients with mild Alzheimer's disease got a
daily omega-3 supplement while 15 patients received a placebo, or dummy pill.
According to Freund-Levi's group, patients who got the supplement showed
higher levels of two major forms of omega-3 fatty acids in their cerebrospinal
fluid, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The placebo
group displayed no such change.
Concentrations of DHA in cerebrospinal fluid were directly linked to the
degree of change in Alzheimer's disease symptoms and in markers of inflammation
in the fluid. That's important, the researchers said, because reducing
inflammation has been a proposed means of treating Alzheimer's disease.
"[The finding] suggests that omega-3 fatty acids in dietary supplements
cross the blood-brain barrier," co-author Jan Palmblad said in the news
release. "However, much work remains to be done before we know how these
fatty acids can be used in the treatment of Alzheimer's disease to halt memory
The study was funded with grants from the Capio Research Foundation, the
Dementia Association, the Swedish Alzheimer's Association and Norwegian omega-3
producer Pronova Biocare A/S, among others.
Find out more on Alzheimer's here.
Find out more about omega-3 fatty acids and Alzheimer's disease at the Alzheimer's Association.