Elwood completed four house jobs and six months in general practice, before opting towards epidemiology and studying whether some lung diseases favoured Northern Irish flax workers.[1]
His work has included a 35 year study involving over 2,500 men, on the effects of aspirin on platelets and heart disease, carried out in Caerphilly, Wales.[2]
He showed that absorption of iron from iron salts added to bread was at "about 4 per cent" in women with low hemoglobin level, which was lower than the previously assumed amount of "about 30 per cent".[3] He showed that giving milk to vulnerable children at school was beneficial but was not re-implemented.[3]