B vitamins are a group of water-soluble vitamins. They include thiamin, riboflavin, niacin, pantothenic acid, folic acid, biotin, pyridoxine and cobalamin. Symptoms of vitamin B deficiency vary depending on which vitamin is lacking.
The primary presentation of mild vitamin B12 deficiency is anemia. Severe deficiency symptoms include fatigue, pale skin, rapid heartbeat, sore tongue, diarrhea or constipation, bleeding gums and weight loss . Symptoms of vitamin B2 deficiency are angular stomatitis and cheilosis, that are gradually replaced by superficial linear cracks. These cracks can get infected by Candida leading to white lesions. Seborrheic dermatitis affects ears, scrotum, nasolabial folds and eyelids which later become reddish. Symptoms of vitamin B6 deficiency in adults include depression, seizures and confusion. Peripheral neuropathy, pellagra with glossitis, seborrheic dermatitis and cheilosis are also the symptoms of Vit.B6 deficiency.
Diagnosis of vitamin B12 deficiency is performed by measuring the levels of vitamin B12 and folate in the blood. Complete blood count is also done to look for anemia. If diagnosis of intrinsic factor deficiency is considered important, Schilling test is also performed. Most common diagnostic tool for Vitamin B6 deficiency is measuring the levels of serum pyridoxal phosphate. Urinary excretion of riboflavin is measured for diagnosing vitamin B2 deficiency. Diagnosis is also performed by therapeutic trial.
The treatment for vitamin B12 deficient patients consists of vitamin B12 injections  . Riboflavin of 5 mg to 10 mg orally once a day is given as a supplement along with other water soluble vitamins to treat vitamin B2 deficiency. In adults, the deficiency of vitamin B6 is treated using pyridoxine 50 mg to 100 mg orally once a day. People taking isoniazid can also be prescribed with pyridoxine of 30 mg to 50 mg orally once a day. High doses of pyridoxine are effective in the case of inborn errors of metabolism. For pyridoxine deficiency from metabolic demand, large amounts of pyridoxine are necessary.
The prognosis of vitamin B2 deficiency is extremely good when vitamin B2 supplements along with a well-balanced diet are taken. Several patients taking treatment with these supplements will recover in a few weeks period. Negative prognosis is related to conditions like alcoholism, anorexia nervosa or bulimia nervosa. These diseases prevent the patient from taking healthy diet and vitamin supplements .
The primary deficiency of vitamin B6 can result from depletion of B6 rich foods in the body. Secondary deficiency is caused by malabsorption, under-nutrition, the use of pyridoxine inactivating drugs and enhanced metabolic demand as seen in hyperthyroidism. Rare intricate errors in metabolism can influence metabolism of pyridoxine. Primary riboflavin deficiency occurs due to insufficient intake of fortified cereals, animal products and milk. Secondary riboflavin deficiency occurs due to chronic diarrhea, liver disorders, peritoneal dialysis, malabsorption syndrome, hemodialysis, chronic alcoholism, long-term use of barbiturates. Autoimmune disorders, pernicious anemia, atrophic gastritis, Crohn’s disease, celiac disease, weight-loss surgery, Grave’s disease and long-term use of acid-reducing drugs are some of the causes of vitamin B12 deficiency .
Framingham offspring study found that 39 percent of US adults are at a higher risk for vitamin B12 deficiency with serum vit. B12 < 258 picoMol/L or <350picograms/mL. Prevalence of vitamin B12 deficiency is observed in 5% to 15% of population. This deficiency is higher in developing countries. Low serum vitamin B12 was <148picomols/L or <200 picograms/mL in 25% to 70% of the population studied. According to the national institute of health, deficiency of Vit. B6 is considered as rare in the United States. When present, it can lead to anemia. A European population based study revealed higher plasma concentrations of vitamin B2 and B6 to be associated with a lower risk in colorectal cancer  .
During cobalamin deficiency, methylmalonic acid and homocysteine levels increase in the blood. The gastrointestinal and hematologic anomalies in this condition might be due to deficiency in DNA synthesis in the quickly dividing cells of bone marrow and gastrointestinal tract. Neurological effects of this condition are thought to be due to the incorporation of cobalamin based synthesis of succinyl CoA into branched chain fatty acids leading to abnormal myelination. Cobalamin in the food is attached to the salivary protein called “R binders” at lower pH in the stomach. Higher duodenal pH promotes the transfer of cobalamin to the proteins of gastric parietal cell protein called intrinsic factor. Cells of ileum absorb the cobalamin-intrinsic factor complex  .
The fuel that is essential for the body consists of a nutritious diet containing carbohydrates, proteins and fats. B vitamins help the body to make use of this fuel. As a result, the human body lacks energy in the absence of vitamin B.. Other B-group vitamins play an important role in the multiplication of cells by making new DNA. Vitamin B supplements are known for suppressing the deficiencies of other vitamins. DNA and red blood cells are made in the body with the help of vitamin B12. Diseases of small intestine, thinning of stomach lining and surgery that removes part of the stomach are some of the reasons for vitamin B12 deficiency. There are eight types of vitamin B. They are B1 or thiamine, B2 or riboflavin, niacin, pantothenic acid, biotin, vitamin B6 or pyridoxine, folate and vitamin B12 . Riboflavin is associated with carbohydrate metabolism and acts as a coenzyme in the oxidation-reduction reactions. Deficiency of riboflavin leads to sore throat, lesions of lips and mucosa of the mouth. If B6 vitamin is excessively processed, it will get depleted from the resultant food. Secondary deficiency results from various conditions.
Vitamin B deficiency does not allow the human body to synthesize carbohydrates, fats and proteins. Therefore, the body will not be able to utilize the necessary fuel it needs. Vitamin B deficiency leads to lack of energy in the body. Some of the symptoms of vitamin B12 deficiency include fatigue, rapid heartbeat and sore throat. Some of the symptoms of vitamin B6 include pellagra, depression and seizures. Some of the symptoms of vitamin B2 include angular stomatitis and cheilosis. Vitamin B6 and vitamin B2 deficiency can be treated by providing 50 mg to 100 mg of pyridoxine orally once a day, and 5 mg to 10 mg of riboflavin orally once a day. Vitamin B12 injection serves best for vitamin B12 deficiency.