A lack of iron, resulting in anaemia, is a common cause of headache. The headache sometimes appears before the onset of anaemia, due to a chronic iron deficiency. Brewer's yeast is an excellent source of iron and anaemia can easily be prevented by taking a few teaspoons daily. Never treat iron deficiency by taking artificial mineral supplements. With iron sulfate it is possible to overload the liver and cause the very complaints one is seeking to avoid.