Wednesday, June 1, 2016

Vitamin B3 - Niacin


Vitamin B3, also known as niacin/nicotinic acid, is one of 8 B vitamins. It comes in two other forms:
  • niacinamide (nicotinamide) 
  • inositol hexanicotinate 
These additional forms have different effects from niacin.

All of the B vitamins, commonly referred to as B-complex vitamins, help convert carbohydrates into glucose, which the body uses for energy. B vitamins also help the body use fats and protein and are essential for a liver,  skin, hair, and eye health, as well as helping the nervous system function.

Niacin also helps the body make various sex and stress-related hormones in the adrenal glands and other parts of the body. It can improve circulation and suppress inflammation. All B vitamins are water-soluble, meaning the body doesn't store them.

It's rare for anyone in the developed world to have a vitamin B3 deficiency. In most developed countries, alcoholism is the main cause of vitamin B3 deficiency.

High cholesterol

Niacin has been used since the 1950s to lower elevated LDL bad cholesterol and triglyceride levels in the blood. However, side effects can be unpleasant and even dangerous. High doses of niacin cause:
  • Flushing of the skin
  • Stomach upset (which usually subsides within a few weeks)
  • Headache
  • Dizziness
  • Blurred vision
  • An increased risk of liver damage
A time-release form of niacin can reduce flushing, but long-term use of the time release form has been associated with liver damage. 

Niacin can interact with other cholesterol-lowering medicines and you shouldn't take niacin at high doses without your doctor's supervision.

In one study, men with heart disease slowed down the progression of atherosclerosis by taking niacin along with colestipol. They experienced fewer heart attacks and deaths.

In another study, people with heart disease and high cholesterol who took niacin along with simvastatin (Zocor) had a lower risk of having a first heart attack or stroke, along with an overall lower risk of death. 

A study also showed that men who took niacin alone seemed to reduce the risk of having a second heart attack, although it did not reduce the risk of death.

The Arterial Biology for the Investigation of the Treatment Effects of Reducing Cholesterol (ARBITER) 2 study investigated the incremental effect of adding niacin (1 gram daily) to statin therapy in 167 patients with known CHD and low HDL levels on carotid intima-media thickness (CIMT), a surrogate endpoint for the development of atherosclerosis. 

The addition of extended-release niacin prevented the increase in CIMT compared to simvastatin monotherapy. A comparative efficacy trial (ARBITER6) also showed a significant reduction of baseline CIMT with extended-release niacin (2 grams daily for 14 months), as opposed to ezetimibe (a cholesterol-lowering drug), in patients on statins.

The effects of niacin are dose-dependent. Doses of niacin higher than 1 gram/day are typically used to treat hyperlipidemia. 

A placebo-controlled study in 39 patients taking statins (cerivastatin, atorvastatin, or simvastatin) found that a very low dose of niacin, 100 mg daily, increased HDL cholesterol by only 2.1 mg/dL, and the combination had no effect on LDL cholesterol, total cholesterol, or triglyceride levels. 

At the pharmacologic dose required for cholesterol-lowering effects, the use of niacin should be approached as if it were a drug. Individuals should only undertake cholesterol-lowering therapy with niacin under the supervision of a qualified health care provider in order to minimize potentially adverse effects and maximize therapeutic benefits.