Because the blood spot offers convenience when sampling (no phlebotomist required) it does mean that both plasma and red blood cells will be present in the sample. As we are only interested in long-term dietary exposure to fatty acids (those derived from RBC and not plasma) we clearly state in the instructions that the client should not eat fish or take fish oils for at least 24 hours prior to taking the sample to avoid ‘spikes’ in plasma omega-3 fatty acids. It is best that clients avoid high omega-3 intake over a weekend and then take the blood sample first thing on a Monday before breakfast.
The correlation between blood spot-derived fatty acids and fatty acids isolated from whole blood is extremely high, making blood spot results a reliable indicator of the omega-3 index and reflect the client’s consumption of omega-3.
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