New blood test more convenient for measuring important omega-3 levels
Researchers have developed a more convenient way of measuring omega-3 fatty acid levels in the blood, an important biomarker of disease risk. The faster, simpler test will make it easier for healthcare professionals to obtain critical information about cardiovascular and cognitive health.
Omega-3 fatty acids have been linked to health benefits, but our bodies don’t produce enough naturally, so we need to get it from what we eat. Two key omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), can only be derived from certain sources, such as oily fish and seafood, enriched foods and supplements.
The omega-3 index (O3I) is the sum of the EPA and DHA found in the membranes of red blood cells. It is a novel biomarker of cardiovascular disease, sudden cardiac death, inflammation, and cognitive dysfunction, independent of traditional risk factors.
However, existing tests to measure the O3I require a large amount of blood to be drawn and time-consuming, complicated laboratory work to analyze the omega-3 fatty acid content. As a result, most clinicians don’t routinely measure the O3I. Now, researchers from McMaster University in Canada have developed a simpler, more convenient test for this important biomarker.
“Testing for the O3I is a complicated procedure, so it’s not routinely available for patient screening despite the popular use of fish supplements and promising clinical evidence of the many health benefits from optimal omega-3 fatty acid nutrition,” said Philip Britz-McKibbin, corresponding author of the study. “This should make it much more convenient to do routine testing since dosage levels and product formulations differ widely in their exact omega-3 fatty acid composition.”
The researchers used multisegment injection-nonaqueous capillary electrophoresis-mass spectrometry (MSI-NACE-MS) to identify circulating phospholipids, particularly phosphatidylcholines (PCs), as surrogate biomarkers of the O3I. MSI-NACE-MS provides faster results and requires only small volumes of blood to be taken.
Study participants were given between three and five grams of fish oil, EPA, or DHA supplements daily. The researchers found that serum or plasma concentrations of two circulating PCs provided the strongest correlation to the O3I, reflecting local changes in red blood cells after receiving supplements for a minimum of 28 days. In high-dose fish oil and EPA-only trials, PC (16:0_20:5) was the most responsive phospholipid, whereas PC (16:0_22:6) was selective to DHA-only supplementation. They found that the sum of both PCs in fasting serum or plasma samples was positively correlated to the O3I following fish oil, EPA- and DHA-only supplementation.
Overall, DHA was found to be more effective in improving the O3I in the study sample compared to EPA.
“In general, if you have an O3I below 4% you may have a higher risk for a cardiovascular-related event,” said Britz-McKibbin. “Conversely, individuals with an O3I above 8% have a lower risk. But since O31 is a modifiable risk factor, you can change it through diet.”
The newly discovered biomarkers of the O3I will make it easier to study omega-3 fatty acids from the perspective of population health.
“By directly measuring only two specific biomarkers in a blood sample, we can rapidly assess the omega-3 index without time-consuming and costly sample workup protocols prior to analysis,” Britz-McKibbin said.
The researchers will next work on identifying a biomarker present in urine, which would eliminate the need to draw blood entirely.
The study was published in the Journal of Lipid Research.
Source: McMaster University