NOW B1 VITAMIN Thiamin (also known as vitamin B1) is water soluble and must be replenished daily, just like the other B vitamin complex vitamins. Vitamin B1 is also called the moral vitamin, due to its effect on the nervous system and mental behavior. If you take it continuously, it can cause vitamin C deficiency, so it is advisable to use it proportionately. Vitamin B1 participates in the metabolism of proteins, fats, and carbohydrates, as well as in cellular metabolic processes. It is necessary for the normal functioning of the nervous system, the proper functioning of the heart and muscles, and can contribute to a proper appetite.