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.
The researchers said fatty acids accumulate naturally in the central nervous system of the fetus 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 said.
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 loss."
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.
-- E.J. Mundell
