Thiamine, also known as vitamin B-1, is one of the B vitamins. Thiamine is a water-soluble vitamin, meaning it washes out of your body in urine, and isn't stored in fat cells like some other vitamins. You need to replenish levels of thiamine regularly, by eating foods rich in this vitamin, or through supplements. Thiamine plays an important role in several bodily functions. Most people in developed countries get enough thiamine in their diets, since a variety of foods supply it.
Thiamine helps your body convert carbohydrates to energy. Carbohydrates can be a good source of steady energy, hence the popularity of athletes "carb-loading" by eating pasta or other carbohydrate-heavy meals the night before a big race. Without thiamine, your body can't use those carbohydrates effectively.
When you eat, food travels down the esophagus to the stomach, where hydrochloric acid digests the food so your body can use nutrients from it. Your body manufactures hydrochloric acid with the help of thiamine. You wouldn't be able to take advantage of many other vitamins and minerals in food without the help of this B vitamin.
Nerves and Muscles
Thiamine helps regulate the flow of electrolytes in and out of the cells of your nerves and muscles. The fat-like covering that surrounds your nerves, called the myelin sheath, enables the proper transmission of nerve signals. Thiamine plays a role in myelin development. Electrolyte imbalances, which can leave you shaky and weak, may have causes other than a lack of thiamine, however.
The Institute of Medicine's Food and Nutrition Board has established recommended intake amounts for thiamine, either from food or from supplements. Males age 14 and older need 1.2 milligrams daily. Girls aged 14 to 18 need 1 milligrams daily, which women 19 and older need 1.1 milligrams. A cup of fortified cereal contains from 0.5 to 2.0 milligrams of thiamine, 3 ounces of cooked pork contains 0.72 milligrams and 1/2 cup of cooked peas contains 0.21 milligrams.