Niacin (Vitamin B3)

Total Niacin in Whole Blood

Clinical Information

Like other B vitamins, vitamin B3 is needed for release of energy from foods. It plays a critical role in in redox reactions in body cells thru its biologically active forms of NAD and NADP. It also plays a role in the production of some hormones and red blood cells 1.

Signs and Symptoms of Deficiency or Toxicity

Niacin deficiency can lead to the disease pellagra. It is characterized by dermatitis, dementi, diarrhea, and death – collectively known as the “4 Ds” 5. Early symptoms of niacin deficiency include loss of weight, strength, and appetite3.

Inadequate intakes and secondary causes as alcoholism and disorders of the digestive system, and prolonged treatment of tuberculosis 3.

Too much intake of niacin manifests thru severe skin flushing combined with dizziness, rapid heartbeat, itching, nausea and vomiting, abdominal pain, diarrhea, and gout 4.

Biomarker and Methods of Analysis


Biochemical testing is considered more useful than dietary data for evaluating niacin status because niacin is in a bound form which makes dietary intake information misleading. The absence and presence of the vitamin reflects the growth of the Lactobacillus plantarum. Growth of bacteria is measured using turbidimetric methods.

Using whole blood is more sensitive than urine in identifying nicotinic acid activity. Furthermore the L. Plantarum responds essentially to nicotinic acid, nicotinamide and nicotinuric acid. 8

Supplementation Guide

For the treatment of pellagra, the daily recommended dose is 300 mg of nicotinamide in divided doses for 3-4 weeks3.

Following are the established upper limits for B3 per age group 9.

  • For children
    • 1-3 y.o.: 10 mg NE
    • 4-8 y.o.: 15 mg NE
    • 9-13 y.o.: 20 mg NE
    • 14-15 y.o.: 30 mg NE
  • For adults, 19 years and older, 35 mg NE

There is no known interaction with medicines.

Food Sources

Good sources are baker’s yeast, liver, cereals, legumes, and seeds. Significant sources also include milk, green leafy vegetables, fish, coffee, and tea 2.

(1) Mayo Clinic Medical Laboratories. (n.d.). Vitamin B3. Niacin in Plasma. Retrieved from
(2) Huskisson E, Maggini S, Ruf M. The role of vitamins and mineral in energy metabolism and well-being. The Journal of International Medical Research 2007; 35: 277-289.
(3) World Health Organization. Dept. of Nutrition for Health and Development (2000). Pellagra and its prevention and control in major emergencies. Geneva: World Health Organization. Retrieved from
(4) Zeratsky, K. (n.d.) Niacin overdose: What are the symptoms? Retrieved from
(5) Meyer-Ficca M, Kirkland JB. Niacin. Advances in Nutrition: An International Review Journal 2016; 7:556-558. doi:10.3945/an.115.011239.
(6) Creeke PI, Dibari F, Cheung E, van de Briel T, Kyrouussis E, Seal AJ.Whole blood NAD and NADP concentrations are not depressed in subjects with clinical pellagra. Journal of Nutrition 2007; 137: 2013-2017.
(7) Gibson, R.M. (2005). Principles of Nutritional Assessment. New York: Oxford University Press, Inc.
(8) Bralley, J.A., Lord, R.S. (2012). Laboratory Evaluations for Integrative and Functional Medicine. 2nd ed. Duluth, Ga: Metametrix Institute.
(9) Philippine Dietary Reference Intakes. 2015. Department of Science Technology-Food and Nutrition Research Institute.