-top- Deficiency of folic acid is common in the general population, resulting from prolonged stress, chronic alcoholism, viral infection and liver disease. When folic acid is lacking, red blood cells become enlarged and oxygen carrying capacity is reduced, resulting in symptoms of breathlessness, headache, pallor, muscle fatigue and exhaustion. Additionally, deficiency of folic acid (along with vitamin B6), is associated with elevated plasma levels of homocysteine