John: Hello, I'm John Hilton, editor in the Cochrane Editorial and Methods department. Heart attack and stroke are the most common causes of death, illness, disability and reduced quality of life in industrialised countries, and several Cochrane Reviews look at ways to prevent these cardiovascular events. A new review from June 2017 looks at the evidence for a B-vitamin called niacin. One of the reviews’ authors, Matthias Briel from Basel Institute for Clinical Epidemiology and Biostatistics in Switzerland, outlines the findings in this podcast.

Matthias: The main group of drugs for preventing heart attacks and strokes are the statins, and these have been shown to lead to significant risk reductions. However, many cardiac events still occur even when people are taking a statin and some people can’t tolerate statin therapy or have contraindications for these drugs. So, alternatives are needed.
Niacin, or vitamin B3, is one of the drugs considered promising to reduce the remaining risk, because it decreases low-density lipoprotein or LDL-Cholesterol (the so called “bad cholesterol”), triglycerides and lipoprotein (a). It is also the most effective currently available drug to increase high-density lipoprotein or HDL-cholesterol levels (the “good cholesterol”), but it does have side effects. These include skin flushing which occurs in about 70% of patients, and much less frequently, headache, itching, and gastrointestinal symptoms.
Therefore, it’s important to know how effective it is and our objective in doing this Cochrane Review was to assess the effects of niacin therapy versus placebo when given as either monotherapy or as add-on to statin-based therapy in people with cardiovascular disease or at risk of cardiovascular disease. We were particularly interested to see what happened for outcomes such as strokes and heart attacks, and to examine the potential side effects.
We identified 23 eligible randomised trials, including almost 40,000 participants that had compared niacin to placebo. Most participants were around 65 years old and had already had a myocardial infarction. The trials tested niacin or placebo for a period of between six months and five years, and 17 of the studies were fully or partially funded by the drug manufacturer with a commercial interest in the results.
Our analyses show that niacin did not reduce the number of deaths, heart attacks or strokes, and almost one in five people had to stop taking niacin due to side effects. The results did not differ between participants who had or had not had a heart attack before joining the trial. Nor did they differ between participants who were or were not taking a statin.
There, in a one sentence summary: this moderate to high quality evidence shows no evidence of clinical benefits from niacin therapy in the primary and secondary prevention of cardiovascular disease events.

John: If you would like to look at this evidence for yourself, the full Cochrane Review contains details of all the studies and their results. If you go online to Cochrane Library dot com and search 'niacin and heart attack', you’ll see it at the top of the list.