Together they also combat stress, depression, and cardiovascular disease. B vitamins, which are water soluble, are dispersed throughout the body and must be replenished daily with any excess excreted in the urine. Symptoms of B vitamin deficiency can include oily or scaly skin, upset stomach, headaches, anxiety, moodiness, and heart arrhythmias. Thiamine also plays a role in the synthesis of nerve-regulating substances. Deficiency in thiamine causes beriberi, which is characterized by muscular weakness, swelling of the heart, and leg cramps and may, in severe cases, lead to heart failure and death.
Many foods contain thiamine, but few supply it in concentrated amounts.
Widespread enrichment of flour and cereal products has largely eliminated the risk of thiamine deficiency, although it still occurs today in nutritionally deficient alcoholics. It also serves in the maintenance of mucous membranes. The best sources of riboflavin are liver, milk, meat, dark green vegetables, whole grain and enriched cereals, pasta, bread, and mushrooms. Niacin, also known as nicotinic acid and vitamin B3, also works as a coenzyme in the release of energy from nutrients. A deficiency of niacin causes pellagra, the first symptom of which is a sunburnlike eruption that breaks out where the skin is exposed to sunlight.