Niacin: Functions,Deficiency Symptoms ,Vegan Foods,Daily Intake

Medically reviewed by

Introduction

Niacin (vitamin B3) is a water-soluble B vitamin and like other B vitamins, it helps to increase energy.

Niacin acts as a coenzyme and more than 400 enzymes are involved in the various reactions and are dependent on it. ^[1,2]

It comes in two forms in food and supplements, being nicotinic acid and nicotinamide.

Plant-based foods provide less niacin per serving than animal-based foods.^[1]

In some grain products especially, bioavailability reduces due to the presence of certain anti-nutrients and only 30 % of niacin becomes available, hence many of the bread, cereals and flours are fortified with niacin. ^[3]

Niacin is absorbed primarily in the small intestine, but some are absorbed in the stomach, even at high doses of 3–4 g. ^[1]
The absorption rate varies between 23 and 70 %; it is lowest from cereals and highest from animal products. ^[5,6]
Excess niacin might be taken up by red blood cells to form a circulating reserve pool. ^[1]

Being a water-soluble vitamin, only essential levels of niacin are stored in various body tissues. ^[2]

Excess or unmetabolised niacin is excreted in the urine. ^[1]
Excretion rates in adults of more than 17.5 micromol/day reflect adequate niacin status and when excretion rates are less than 5.8 micromol/day it indicates niacin deficiency. ^[1,3]

Body Functions

Intracellular respiration ^[1]

Role in calcium mobilisation ^[4]

Converts nutrients into energy ^[4,5]

Creates and repairs DNA^[5]

Fatty acid synthesis ^[1,4]

Lowers cholesterol levels ^[7]

Intracellular respiration ^[1]

Role in calcium mobilization ^[4]

Converts nutrients into energy ^[4,5]

Creates and repairs DNA ^[5]

Fatty acid synthesis ^[1,4]

Lowers cholesterol levels ^[7]

Recommended Daily Intake

how much vitamin b3 niacin is recommended daily

Deficiency Symptoms

Niacin deficiency leads to a disease called pellagra that has the following symptoms –

Pigmented rash on the skin ^[1,2]

Gastrointestinal disturbances ^[1,2,4]

Apathy ^[2]

Depression ^[2,4]

Loss of memory ^[1,2]

Headache ^[2]

Fatigue ^[2,4]

Mouth & tongue inflammation ^[4]

Pigmented rash on the skin ^[1,2]

Gastrointestinal disturbances ^[1,2,4]

Apathy ^[2]

Mouth & tongue inflammation ^[4]

Depression ^[2,4]

Loss of memory ^[1,2]

Headache ^[2]

Fatigue ^[2,4]

Niacin Food Sources

Excessive Intake/ Toxicity Side Effects

Skin flushing and rashes [1,4]

Tingling, burning sensation ^[1]

Blurred vision ^[1,2]

Headache ^[1]

Liver toxicity risk ^[1,2]

Dizziness and low blood pressure ^[1]

Gastrointestinal effects ^[4]

Vomiting ^[1,2,4]

Skin flushing and rashes ^[1,4]

Tingling, burning sensation ^[1]

Blurred vision ^[1,2]

Headache ^[1]

Impaired glucose tolerance and insulin resistance ^[2]

Liver toxicity risk ^[1,2]

Dizziness and low blood pressure ^[1]

Gastrointestinal effects ^[4]

Groups At Risk of Riboflavin Deficiency

Groups at risk of Niacin deficiency

People who are undernourished due to poverty, AIDs, inadequate diet or due to inflammatory bowel disease are at risk of niacin deficiency ^[1].

Chronic alcoholics

As with other water-soluble vitamins, excessive alcohol intake may increase urine excretion and thereby reducing niacin body levels ^[5].

Niacin Interaction With Other Nutrients

Iron – As with the vitamin B2 and B6, inadequate intake can also impact niacin levels ^[2,3].
Certain B-vitamins – Inadequate intake of vitamin b2 and vitamin b6 may impact niacin status as the enzymes used to convert tryptophan to niacin depend on these nutrients ^[1,2].