An Omega-3 Index test from OmegaQuant can determine your Omega levels in the blood. If your son is consistently eating seafood and taking his Omega-3 supplements then his tests will show higher than 8% in the Omega-3 Index. While individuals who do not are at 3-4%.
If you quit eating seafood and taking Omegas, the OmegaQuant numbers will go back down to 3% after a couple of months.