Vitamin B-1, or thiamin, is a water-soluble vitamin necessary for carbohydrate metabolism and nerve and heart function. A deficiency of vitamin B-1 is uncommon, but when it does occur you may experience symptoms that include a loss of appetite, numbness or "pins and needles" in the legs, and muscle tenderness. Severe deficiency may lead to potentially serious complications in the nervous system, heart, muscles, and gastrointestinal system. Eating a balanced diet high in whole grains, lean meats and beans will ensure blood levels of vitamin B-1 remain consistent.
Cereals and Grains
The Linus Pauling Institute lists long-grain brown rice, wheat germ, whole wheat bread, brewer's yeast, and fortified breads, cereals, and pastas as leading sources of dietary vitamin B-1. Processed grains and cereals provide considerably less vitamin B-1 than unprocessed grains. During processing grains lose B vitamins, up to 75 percent of important phytochemicals and up to 80 percent of mineral content, according to the Minnesota Department of Health. Because of this, many foods made with white flour and white rice are fortified with vitamin B-1 in the United States. A 1-cup serving of fortified white rice has 0.3 milligrams of thiamin, or nearly 25 percent of the recommended intake of 1.1 to 1.2 milligrams.
Meat and Dairy
Lean meats are rich in vitamin B-1, according to the National Institutes of Health, with lean pork containing more of the vitamin than any other meat. Fish, liver, beef, dairy products, and eggs also provide vitamin B-1, with one serving of yellow fin tuna containing nearly 40 percent of the daily value of B-1. Roasting, stewing and broiling meats tends to reduce B-1 content more than frying.
Beans, Nuts and Seeds
Nuts, beans and seeds are excellent dietary sources of vitamin B-1, and these foods make ideal meat replacements for vegetarians or those on restricted diets. One serving of raw sunflower seeds provides more than half of the daily value of vitamin B-1, with cooked black beans and navy beans providing 25 percent. Pinto beans, soybeans, lima beans, Brazil nuts and pecans are other good sources of the vitamin.
Fruits and Vegetables
The National Institutes of Health states that vegetables and fruits are good sources of vitamin B-1 when eaten in abundance. Eating fresh fruits and vegetables offers more B-1 than eating frozen or refrigerated fruits and vegetables, and long-term refrigeration results in a significant loss of vitamin B-1 content. Romaine lettuce, spinach, asparagus, green peas, eggplant, oranges, cantaloupe, brussels sprouts and tomatoes are all good sources of vitamin B-1.