significant differences between the various pairs of twins some react more and others less strongly to the high fat diet. the conclusion of the study is that blood cholesterol levels are mainly a question of genes. could it be whether the cholesterol level is high or low is genetically determined through diet can be raised or lowered by about fifteen percent someone with a very high level won t end up with a low one by having a healthy diet yet the influence of nutrition on cholesterol levels is just not that great that s one reason why cardiologist melanie american has stopped telling her patients to stay away from butter entirely another reason is that current cholesterol lowering drugs are very effective. she says it would nonetheless be very wrong to issue an all clear. yet. we cardiologists have to be careful not to say oh eat what you like it doesn t matter have liver