Vitamin B1 or thiamine, as it is more commonly referred to now, is one of the most important members of the B group of vitamins. Also known as aneurin, vitamin B1 is anti-beriberi and anti-neuritic. It is water soluble.
A lack of sufficient thiamine in the diet can cause loss of appetite, poor digestion, chronic constipation, loss of weight, mental depression, nervous exhaustion, and insomnia. It can lead to muscular weakness, leg cramps, slow heartbeat, irritability, defective hydrochloric acid production in the stomach and consequent digestive disorders. In case of insufficient supply of thiamine in the body, the heart muscles become lazy and fatigued, and the auricles or the upper chambers of the heart lose their strength and gradually enlarge.