The Problems with Niacin

Niacin causes flushing to the skin. This is an allergic reaction, a histamine reaction. To avoid that, I’ve been using niacinamide, which causes less flushing. Both are referred to as “niacin” in this article.

As of today, I’ve been avoiding Niacin for about 30 days, and I feel better mentally. I also eliminated a rash on my head. And also, seasonal allergies such as runny nose were eliminated. And I’m running more. These are all changes that happened after stopping niacin, and could be related.

The RDA for niacin ranges from 14 to 18 mg.

The average American diet provides from 15 to 34 mg of niacin.

About 4-10 mg of the niacin in the diet comes from food fortification, mostly in flour and breads.

Tryptophan, an amino acid found in meat, is a precursor to Niacin, so the body makes niacin from protein.

A half a pound hamburger provides 540 mg of tryptophan, which can be converted, or turned into, up to 9 mg of Niacin.

Niacin can also be made in the gut by bacteria, but this amount is unknown, and can vary wildly, and more research is needed to better estimate this amount.

Note, these are 4 sources of niacin. The diet. The fortified diet. Protein as the body makes it. And finally gut bacteria make it. Supplementation would be a 5th source of niacin.

Eliminating supplementation is thus NOT a zero niacin program. Even without supplementation, most people get well over the RDA.

Niacin deficiency rates in America are well under 1%.

Pellagra, a rash around the neck and sometimes hands (from sun exposure), a specific niacin deficiency disease, is so rare it’s almost never seen, and is not tracked nor counted by the CDC. Nor are there any studies on the incidence rates, because it’s so rare. It’s likely less than 1 in a million.

Pellagra can be seen in people who eat a diet very heavy in corn. The tryptophan content of corn is 0.04%. Milling of corn removes tryptophan.

Because most people easily meet or exceed the RDA, there is no need to supplement niacin.

Alcohol can deplete niacin, but even with high rates of alcoholism, niacin deficiency remains extremely rare.

A reasonable amount to supplement niacin would be a low dose of 14 to 18 mg, which is considered safe.

Therapeutic doses are around 500 to 2000 mg, and should be done under medical supervision, because they can cause liver disease and other problems.


Skin reactions:
Flushing (redness, warmth, itching, tingling of the skin)
Dry skin
Skin rash

Gastrointestinal issues:
Abdominal pain
Peptic ulcers (in severe cases)

Liver problems:
Elevated liver enzymes
Hepatotoxicity (liver damage)
Jaundice (yellowing of skin and eyes)

Metabolic effects:
Increased blood sugar levels
Worsening of diabetes control
Gout flare-ups due to increased uric acid levels

Cardiovascular effects:
Rapid or irregular heartbeat
Low blood pressure (especially when changing positions)

Blood abnormalities:
Platelet dysfunction
Increased risk of bleeding

Eye problems:
Blurred vision
Toxic amblyopia (in rare cases)

Muscle effects:
Muscle damage (myopathy)
Elevated creatine kinase levels

Neurological effects:
In severe cases, stroke-like symptoms
Mental confusion and mental difficulties
Stimulates the reward center of the brain like alcohol and cigarettes

Increased homocysteine levels (a risk factor for heart disease)
Birth defects (if taken in high doses during pregnancy)
Activation of peptic ulcers
Decreased running
Laxity and increased flexibility, and decreased rebounding in the joints

Long-term high-dose effects:
Potential increased risk of certain types of infections
Possible increased risk of some types of strokes (still under research)

The severity and likelihood of these side effects can vary based on the dose, duration of use, form of niacin, and individual factors.

Serious side effects are rare with normal dietary intake or low-dose supplementation, but still happen.

Many of these side effects appear to be similar to copper deficiency, zinc deficiency, and/or other toxic effects such as Vitamin A toxicity, or salt toxicity.

I recognize many of these effects as being common in our forum when we were recommending niacin, such as:

  1. bleeding
  2. increased heart racing problems
  3. headaches
  4. tiredness and mental confusion

Some of the effects of niacin are shocking and alarming.
It worsens diabetes?
Causes mental confusion?
Causes nausea?
Causes liver disease, heart disease, and strokes? Those are not mild symptoms.

It also seems counterintuitive as B Vitamins are known for increasing energy. Why then does niacin cause increased sleepiness and being tired?

See also, my prior article on Niacin from 2022:

At this time, I have discontinued taking Niacin, until I see signs of Niacin deficiency. These symptoms are:

Skin issues:
Photosensitivity (increased sensitivity to sunlight)
Thick, dry, or rough skin +
Red, inflamed skin (dermatitis) +
Skin lesions, especially in sun-exposed areas

Digestive problems:
Bright red tongue (glossitis)
Swollen, red lips
Mouth sores or ulcers
Nausea +
Vomiting +
Abdominal pain +
Diarrhea +

Neurological symptoms:
Headaches +
Fatigue +
Memory loss +
In severe cases, dementia-like symptoms

Other symptoms:
Loss of appetite
Weight loss
Dizziness +

In severe cases (pellagra), often described as the “4 D’s”:
Dermatitis (skin inflammation)
Diarrhea +
Dementia (cognitive impairment)
Death (if left untreated)

Additional potential effects:
Reduced metabolism
Decreased tolerance to cold

In children:
Growth retardation
Delayed development

  • Every symptom noted with the “+” sign is also a symptom of excess niacin.


I have an idea. Niacin appears to deplete copper.

In the process of depleting copper, niacin would first have to mobilize it. The key feature of niacin deficiency, pellagra, appears to be sun sensitivity, which is also a sign of copper deficiency, as copper is needed to make melanin to help the skin to tan and not burn. Other signs of niacin deficiency also appear to be signs of copper deficiency such as anemia, reduced metabolism, decreased tolerance to cold, dementia, dermatitis, weakness, weight loss, dizziness, insomnia, ulcers, basically everything.

It could be that niacin only temporarily relieves these problems of copper deficiency, and only appears to relieve these apparent problems of copper deficiency, when then appear to be signs of niacin deficiency. The big idea here is that if we are taking enough copper then none of these signs of copper deficiency (niacin deficiency) would ever appear. It’s worth a test. We will see.

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