Nicotinic acid (NA), often called niacin, a form of vitamin B3, is a water-soluble nutrient found in animal and vegetarian foods. Vitamin B3 for healthy people is considered to be needed in doses of less than 20 mg daily. In higher doses, NA has been described to be beneficial in some patients with psychiatric disorders. This report describes a male patient with bipolar type II disorder who for many years had been treated with lithium and other medications applied in affective disorders. These pharmacological drugs had beneficial effects but were at times insufficient. When the patient was prescribed NA, he experienced a comparatively strong effect. Slowly it was discovered that the patient could lower and cease all medications except NA.
For over 11 years he has been stable and calm with NA and currently takes 1 g three times daily. When not taking NA, he consistently became anxious and depressed within 2–3 days. The resumption of NA resulted in a normal state usually within 1 day. This finding has been described as a vitamin dependency. The paper discusses possible mechanisms for the effect of NA in this patient. Further studies are needed to investigate the prevalence of vitamin B3 dependency and the biochemical explanations for this phenomenon.
Whenever the patient forgot to take NA or decided to test not taking it, he consistently became anxious within 2 to 3 days. When P resumed taking NA, he would usually feel normal within a day.
The phenomenon that a high-dose vitamin is needed for treatment of a diagnostic entity in some patients has been described as a vitamin dependency. This concept is most well known for vitamin B6 with respect to a form of epilepsy described in children. The explanation for a higher need of vitamin B6 can be related to use of interfering drugs, somatic disease with malabsorption, renal dialysis, an inborn error of metabolism or genetic polymorphism. Vitamin dependency has also been described for vitamins B1, B3, B12, folate, D and K.
What could be the reason for the effect of high-dose NA in this case? Vitamin B3 is usually estimated to be necessary in doses of less than 20 mg daily. The statement is correct if the purpose is to prevent the deficiency disease pellagra in the population. However, if some individuals need a much higher dose of this water-soluble molecule, it is reasonable to assume a specific biochemical explanation for this.
The author has been the treating psychiatrist for this bipolar type II patient for 26 years. Twelve years ago, the patient was prescribed NA as an add-on to conventional medication. Successively, the psychopharmacological drugs were terminated. With NA, currently at 1000 mg three times daily, the patient has for over 11 years been stable and in a good mental health condition without any psychiatric drugs. The most probable explanation is that this is related to specific genetic factors. Such a high-dose need of an essential vitamin is sometimes described as a vitamin dependency. Further studies may help us to see if NA dependency occurs in different patient groups. The investigation of possible genetic polymorphisms is needed for the development of knowledge and the individual treatment of patients.