Niacin Toxicity - Causes, Symptoms, Diagnosis, and Treatment

Introduction

Niacin, also known as vitamin B3, is naturally present in some foods and sold as a supplement. Niacin in food and supplements is commonly found in the form of nicotinic acid and nicotinamide. Niacin helps transform nutrients into energy, produces cholesterol and fat, creates and repairs DNA (deoxyribonucleic acid), and has antioxidant effects. Niacin or vitamin B3, along with other B vitamins, is called the vitamin B complex. These vitamins are necessary for healthy skin, hair, liver, and eyes.

Niacin also helps in the production of various stress-related hormones and sex hormones. Usually, the body’s need for niacin is met through the diet itself. Excessive intake of niacin is called niacin toxicity. When the required amount of niacin does not reach the body, it will lead to a niacin deficiency called pellagra.

What Are the Required Amounts of Niacin?

The recommended dietary allowance (RDA) for niacin is 16 mg NE (niacin equivalents) for men, 14 mg NE for women, 18 mg NE for pregnant women, and 17 mg NE for lactating women.

The tolerable upper intake level (UL) is the amount that is safe to consume daily without any complications. The tolerable upper intake level for niacin for adults above 19 years of age is 35 mg.

What Are the Sources of Niacin?

• Red meat like beef and pork.

• Fish.

• Poultry.

• Fortified cereals and bread.

• Brown rice.

• Seeds and nuts.

• Bananas.

• Legumes.

• Salmon.

• Beets.

• Tuna.

Niacin is also available as a supplement in nicotinamide and nicotinic acid. Niacin is used in the treatment of cholesterol. High doses, up to 2000 mg daily of nicotinic acid, are given as the treatment for cholesterol.

What Is Niacin Deficiency?

Niacin deficiency is very rare in developed countries like the United States. Severe niacin deficiency results in condition called pellagra, characterized by a dark, scaly rash on the skin, diarrhea, and dementia. Other symptoms of niacin deficiency include:

• Headache.

• Depression.

• Hallucinations.

• Vomiting.

• Indigestion.

• Fatigue.

• Memory loss.

• Swelling, bright red tongue.

It is thought that niacin protects brain cells against stress and injury. Severe niacin deficiency is associated with memory loss and dementia.

Who Is at Risk for Niacin Deficiency?

• People with poor diets, like those living in poverty or those who are ill and cannot take a balanced diet, are at high risk of niacin deficiency.

• People with severe alcoholism are also at high risk of niacin deficiency because the absorption of vitamins is affected by alcohol.

• People with carcinoid syndrome (slow-growing cancer cells in the gut) are at risk of niacin deficiency.

What Is Niacin Toxicity?

Toxicity from eating foods rich in niacin is very rare. It occurs due to long-term use of high-dose niacin supplements. Signs of niacin toxicity include:

• Flushed skin with itching or tingling on the face, arms, and chest, which usually occurs after 30 minutes of ingestion. It can occur if the daily intake exceeds 30 mg.

• Liver damage - Clinically manifests as jaundice, vomiting, nausea, fatigue, and itching. Liver damage occurs only if the daily intake exceeds 3 grams.

• Glucose intolerance and liver inflammation in severe cases.

• Low blood pressure.

• Dizziness.

• Headache.

• Stomach upset.

• Nausea.

• Fatigue.

• Blurred vision.

How Is Niacin Toxicity Managed?

1. Emergency management starts with stabilizing the airway, breathing, and circulation. Rewarming is done to manage hypothermia. A dextrose infusion is given for hypoglycemia.

2. In severe cases, a transfusion of fresh frozen plasma or red blood cells is required.

3. For patients with liver damage, appropriate measures are taken, and liver transplantation should be recommended if required.

4. Medication is not required for the flushing of the skin; it is a self-limiting condition. In most cases, stopping the intake of niacin supplements, along with reassurance and proper follow-up, is the only treatment required.

How to Take Niacin Supplements?

Pediatric & Adults:

What Precautions Should Be Taken for Taking Niacin?

• High doses of niacin can cause side effects such as skin flushing. Taking aspirin 30 minutes before niacin may reduce the side effects.

• Because niacin overdose can cause some side effects and its ability to interact with other medications, it should only be taken with a doctor's prescription.

• People with a known history of kidney disease, liver disease, and gastric ulcers should not take niacin supplements.

• People with low blood pressure should not take niacin supplements.

• People with coronary artery disease should not take niacin without medical supervision.

• Niacin should be stopped at least two weeks before surgery.

Conclusion

Niacin is believed to help increase energy. So people tend to take niacin supplements more than the recommended dose without any second thought or medical supervision. This can lead to niacin toxicity. It is recommended to follow the required daily intake and always take the supplement if the doctor prescribes it. If are any signs of niacin toxicity is noted, immediate medical attention should be sought. With timely management, complications like liver failure can be avoided.