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Dear Mr. Scientist,

I know vampires aren’t real, but could a person actually survive on blood?

—Rachel T.

Blood is full of nutrients, and vampire bats can live solely on blood. So it is plausible that a person could live on a blood diet. Ignoring the question of how well your body could absorb nutrients from blood, there’s one problem. Because of its high iron content, blood is toxic. The body has a difficult time excreting excess iron, and too much iron causes a condition called haemochromatosis. This leads to problems like liver damage, low blood pressure and nervous disorders. Vampire bats have developed a mucous membrane along their intestinal tracts that prevents the absorption of too much iron, but humans lack this feature so we could not survive by drinking blood.

Dear Mr. Scientist,

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Is it possible to be literally scared to death?

—Ross G.

It’s rare, but very possible. When we’re startled, our fight-or-flight response releases catecholamines like norepinephrine and epinephrine (adrenaline). These chemicals allow you to fight whatever it is that scared you or run away really fast, but they can also have negative effects on the heart. Given a strong enough dose of catecholamines, you can suddenly develop an irregular heartbeat, the blood vessels of your heart can close up or the heart may even stop—all of which can kill you. For the average person the likelihood of experiencing stress cardiomyopathy is highly unlikely, but it does happen every once in a while to people with a history of heart disease.

Ask Mr. Scientist is written by Michael Leitch. If you have a burning science question you want him to answer, tweet @DC_Science or email it to science@dailycardinal.com.

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