Does acid reflux increase the risk of heart attack?

If you suffer with acid reflux, you might have noticed recent UK headlines suggesting that the condition increases the risk of having a heart attack. But how reliable are these claims?

Acid reflux, which causes the feeling of heartburn, is very common. It affects up to 1 in every 4 of UK adults. When acid reflux is severe and keeps happening, it is called gastro-oesophageal reflux disease or GORD.

Previous research has shown a link between severe acid reflux and heart problems like coronary artery calcification.

But little is known about whether having severe acid reflux means you are more likely to have a heart attack. So, this is what researchers at Jefferson Einstein Hospital in the United States decided to try and find out.

Their study, published in the Journal of Gastroenterology and Hepatology Foundation, showed those with severe acid reflux had a 27 per cent higher risk of having a heart attack compared to those without.

But is this statistic really telling the whole story, and what does it mean for people with the condition?

What is acid reflux?

Acid reflux happens when acid in the stomach that breaks down food, escapes and flows the wrong way up into the food pipe (oesophagus).

Sometimes this can cause symptoms like a burning feeling in the middle of the chest (heartburn) and an unpleasant sour taste in the mouth. These symptoms often worsen after eating fatty or spicy foods, citrus juice, fizzy drinks, tea and coffee, or alcohol.

While the exact causes of acid reflux are not always clear, there are some things that increase the risk of having it. These include lifestyle factors such as drinking too much alcohol, smoking, and carrying excess weight.

Importantly, these factors are also known to raise the risk of coronary heart disease which causes most heart attacks.

What did the research find?

The research examined 6 studies covering around 1.3 million people from countries in Europe and Asia. These studies compared the incidence of heart attack among people with severe acid reflux to those without.

By analysing all the results from the 6 studies, the researchers found that people diagnosed with severe acid reflux had a 27 per cent increased risk of having a heart attack compared to those who did not have it.

The paper concluded that severe acid reflux may contribute to an increased risk of heart attack, and that more investigations are needed to find out if better treatment of the condition, and healthier lifestyles, could help lower the risk of heart attack in people with GORD.

What do the researchers say?

The researchers say this is the first large review of the science into severe acid reflux and heart attack risk.

And, although they found a link between severe acid reflux and an increased risk of heart attack, the findings do not prove that severe acid reflux directly causes heart attack, as other factors could be involved.

The researchers give several possible reasons as to why the two conditions are linked.

They say it could be because severe acid reflux and coronary heart disease – already known to raise the risk of heart attack - share several risk factors such as smoking, drinking too much alcohol, living with excess weight, and being male.

This means the same lifestyle factors causing severe acid reflux among the study’s participants could have increased their risk of heart attack too.

Some participants may even have had coronary heart disease but were not diagnosed, the researchers say.

They also suggest that inflammation in the body caused by severe acid reflux could play a part in increasing the risk of heart attack by contributing to the build-up of fatty deposits in the artery supplying blood to the heart.

This process is called atherosclerosis which is known to raise the risk of a heart attack.

Previous research linking medicines commonly used to treat acid reflux, called proton pump inhibitors (PPIs), to an increase in heart attack risk should also be taken into account. The researchers point out that if people in the study were taking PPIs then these may have been behind their increased heart attack risk – not their acid reflux.

Severe acid reflux might also trigger an automatic nervous system response in the body that reduces blood flow to the heart muscle, the researchers say. But more evidence is needed to prove this.

How good was the research?

A key strength of the research is its huge scale – using data from over 1.3 million people. Another is the strict way the researchers decided which studies from 2 big medical databases to include – whittling thousands down to just 6.

However, the 6 studies included were all observational, meaning the research does not prove acid reflux caused the participants’ heart attacks – just that the two conditions are linked.

The 6 studies were also carried out differently, making the results less accurate. For example, the way severe acid reflux and heart attack were diagnosed in each study was not the same - some used self-reported symptoms, and others used medical classification systems, or both.

It’s also not clear whether all 6 studies properly accounted for all the risk factors that are common to both severe acid reflux and heart disease – such as smoking, drinking alcohol and having excess weight – which could have affected the accuracy of the results too.

How good was the media coverage?

The study was covered in the Daily Mail, which did a good job of reporting on it accurately. While the headline might have sounded dramatic, “Acid reflux increases risk of heart attack by nearly a third, new study reveals”, it was not misleading as they went into cause and effect in their article.

When it came to reporting on the possible causes, the Daily Mail focused on inflammation and the automatic nervous system response saying these were “likely to be the cause of this increased risk”.

But this overstated the researchers carefully worded findings that inflammation “may contribute” to heart attack risk and that the “evidence was limited” around the role of the nervous system.

The BHF’s verdict

At present, there is not enough evidence to say that severe acid reflux directly causes an increase in heart attack risk. What we do know is that the lifestyle factors that can cause severe acid reflux can also raise the risk of developing heart disease – the cause of most heart attacks.

The research underscores the importance of making lifestyle changes, such as stopping smoking, limiting alcohol intake, and staying a healthy weight, to help reduce your risk of getting heart disease and severe acid reflux.

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