Investigations reveal vitamin A deficiency. Again, there has to be 90 to 110 mg of sugar for every 100 cubic centimeters of body volume. Slight deficiency causes emotional disorders. The man becomes ill-tempered and in extreme cases can even become a murderer. Modem science has proved that ill-temper and the murderous tendency are caused by a deficiency of sugar, niacin and certain vitamins.
Chemical deficiency can cause depression.
Similarly, one of the causes of fear is vitamin B deficiency. A lot of research is being carried on these days on the properties of a chemical called tryptaphane which produces serotonin. It has been found that an adequate quantity of serotonin in the blood prevents moodiness and fear and increases tolerance to pain. Advocates of non-vegetarianism often advance richness in protein as the chief argument in favour of meat and eggs. But now it is realized that excessive protein causes all kinds of physical and mental disorders.