The USA embargo in Cuba is not causing a famine because there is no famine. So you’re vitamin A deficiency did not cause your black eye, because you have enough vitamin B and C, and also you don’t have a black eye.
Also the embargo de jure excludes food and medicine (although de facto it is hard to export those to Cuba), but also subsidiaries of USA companies are also not allowed to trade with Cuba, so Canadian and EU companies which do business in the USA (which is almost everybody) are risking a lot by trading with Cuba, so in effect the embargo is somewhat extended by large parts of EU and Canada.
Also the embargo de jure excludes food and medicine (although de facto it is hard to export those to Cuba), but also subsidiaries of USA companies are also not allowed to trade with Cuba, so Canadian and EU companies which do business in the USA (which is almost everybody) are risking a lot by trading with Cuba, so in effect the embargo is somewhat extended by large parts of EU and Canada.