If you Google the terms “constipation” and “heart attack” it’s not long before the name Elvis Presley crops up. Elvis had a longstanding history of chronic constipation and it’s believed he was straining very hard to poo, which then led to a fatal heart attack.

We don’t know what really happened to the so-called King of Rock “n” Roll back in 1977. There were likely several contributing factors to his death, and this theory is one of many.

But after this famous case researchers took a strong interest in the link between constipation and the risk of a heart attack.

This includes a recent study led by Australian researchers involving data from thousands of people.

Are constipation and heart attacks linked?

Large population studies show constipation is linked to an increased risk of heart attacks.

For example, an Australian study involved more than 540,000 people over 60 in hospital for a range of conditions. It found constipated patients had a higher risk of high blood pressure, heart attacks and strokes compared to non-constipated patients of the same age.

A Danish study of more than 900,000 people from hospitals and hospital outpatient clinics also found that people who were constipated had an increased risk of heart attacks and strokes.

It was unclear, however, if this relationship between constipation and an increased risk of heart attacks and strokes would hold true for healthy people outside hospital.

These Australian and Danish studies also did not factor in the effects of drugs used to treat high blood pressure (hypertension), which can make you constipated.

How about this new study?

The recent international study led by Monash University researchers found a connection between constipation and an increased risk of heart attacks, strokes and heart failure in a general population.

The researchers analysed data from the UK Biobank, a database of health-related information from about half a million people in the United Kingdom.

The researchers identified more than 23,000 cases of constipation and accounted for the effect of drugs to treat high blood pressure, which can lead to constipation.

People with constipation (identified through medical records or via a questionnaire) were twice as likely to have a heart attack, stroke or heart failure as those without constipation.

The researchers found a strong link between high blood pressure and constipation. Individuals with hypertension who were also constipated had a 34% increased risk of a major heart event compared to those with just hypertension.

The study only looked at the data from people of European ancestry. However, there is good reason to believe the link between constipation and heart attacks applies to other populations.

A Japanese study looked at more than 45,000 men and women in the general population. It found people passing a bowel motion once every two to three days had a higher risk of dying from heart disease compared with ones who passed at least one bowel motion a day.

How might constipation cause a heart attack?

Chronic constipation can lead to straining when passing a stool. This can result in laboured breathing and can lead to a rise in blood pressure.

In one Japanese study including ten elderly people, blood pressure was high just before passing a bowel motion and continued to rise during the bowel motion. This increase in blood pressure lasted for an hour afterwards, a pattern not seen in younger Japanese people.

One theory is that older people have stiffer blood vessels due to atherosclerosis (thickening or hardening of the arteries caused by a build-up of plaque) and other age-related changes. So their high blood pressure can persist for some time after straining. But the blood pressure of younger people returns quickly to normal as they have more elastic blood vessels.

As blood pressure rises, the risk of heart disease increases. The risk of developing heart disease doubles when systolic blood pressure (the top number in your blood pressure reading) rises permanently by 20 mmHg (millimetres of mercury, a standard measure of blood pressure).

The systolic blood pressure rise with straining in passing a stool has been reported to be as high as 70 mmHg. This rise is only temporary but with persistent straining in chronic constipation this could lead to an increased risk of heart attacks.

Some people with chronic constipation may have an impaired function of their vagus nerve, which controls various bodily functions, including digestion, heart rate and breathing.

This impaired function can result in abnormalities of heart rate and over-activation of the flight-fight response. This can, in turn, lead to elevated blood pressure.

Another intriguing avenue of research examines the imbalance in gut bacteria in people with constipation.

This imbalance, known as dysbiosis, can result in microbes and other substances leaking through the gut barrier into the bloodstream and triggering an immune response. This, in turn, can lead to low-grade inflammation in the blood circulation and arteries becoming stiffer, increasing the risk of a heart attack.

This latest study also explored genetic links between constipation and heart disease. The researchers found shared genetic factors that underlie both constipation and heart disease.

What can we do about this?

Constipation affects around 19% of the global population aged 60 and older. So there is a substantial portion of the population at an increased risk of heart disease due to their bowel health.

Managing chronic constipation through dietary changes (particularly increased dietary fibre), increased physical activity, ensuring adequate hydration and using medications, if necessary, are all important ways to help improve bowel function and reduce the risk of heart disease.

Vincent Ho, Associate Professor and clinical academic gastroenterologist, Western Sydney University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mark Patrick Taylor, Macquarie University and Scott P. Wilson, Macquarie University

A recent study published in the prestigious New England Journal of Medicine has linked microplastics with risk to human health.

The study involved patients in Italy who had a condition called carotid artery plaque, where plaque builds up in arteries, potentially blocking blood flow. The researchers analysed plaque specimens from these patients.

They found those with carotid artery plaque who had microplastics and nanoplastics in their plaque had a higher risk of heart attack, stroke, or death (compared with carotid artery plaque patients who didn’t have any micro- or nanoplastics detected in their plaque specimens).

Importantly, the researchers didn’t find the micro- and nanoplastics caused the higher risk, only that it was correlated with it.

So, what are we to make of the new findings? And how does it fit with the broader evidence about microplastics in our environment and our bodies?

What are microplastics?

Microplastics are plastic particles less than five millimetres across. Nanoplastics are less than one micron in size (1,000 microns is equal to one millimetre). The precise size classifications are still a matter of debate.

Microplastics and nanoplastics are created when everyday products – including clothes, food and beverage packaging, home furnishings, plastic bags, toys and toiletries – degrade. Many personal care products contain microsplastics in the form of microbeads.

Plastic is also used widely in agriculture, and can degrade over time into microplastics and nanoplastics.

These particles are made up of common polymers such as polyethylene, polypropylene, polystyrene and polyvinyl chloride. The constituent chemical of polyvinyl chloride, vinyl chloride, is considered carcinogenic by the US Environmental Protection Agency.

Of course, the actual risk of harm depends on your level of exposure. As toxicologists are fond of saying, it’s the dose that makes the poison, so we need to be careful to not over-interpret emerging research.

A closer look at the study

This new study in the New England Journal of Medicine was a small cohort, initially comprising 304 patients. But only 257 completed the follow-up part of the study 34 months later.

The study had a number of limitations. The first is the findings related only to asymptomatic patients undergoing carotid endarterectomy (a procedure to remove carotid artery plaque). This means the findings might not be applicable to the wider population.

The authors also point out that while exposure to microplastics and nanoplastics has been likely increasing in recent decades, heart disease rates have been falling.

That said, the fact so many people in the study had detectable levels of microplastics in their body is notable. The researchers found detectable levels of polyethylene and polyvinyl chloride (two types of plastic) in excised carotid plaque from 58% and 12% of patients, respectively.

These patients were more likely to be younger men with diabetes or heart disease and a history of smoking. There was no substantive difference in where the patients lived.

Inflammation markers in plaque samples were more elevated in patients with detectable levels of microplastics and nanoplastics versus those without.

And, then there’s the headline finding: patients with microplastics and nanoplastics in their plaque had a higher risk of having what doctors call “a primary end point event” (non-fatal heart attack, non-fatal stroke, or death from any cause) than those who did not present with microplastics and nanoplastics in their plaque.

The authors of the study note their results “do not prove causality”.

However, it would be remiss not to be cautious. The history of environmental health is replete with examples of what were initially considered suspect chemicals that avoided proper regulation because of what the US National Research Council refers to as the “untested-chemical assumption”. This assumption arises where there is an absence of research demonstrating adverse effects, which obviates the requirement for regulatory action.

In general, more research is required to find out whether or not microplastics cause harm to human health. Until this evidence exists, we should adopt the precautionary principle; absence of evidence should not be taken as evidence of absence.

Global and local action

Exposure to microplastics in our home, work and outdoor environments is inevitable. Governments across the globe have started to acknowledge we must intervene.

The Global Plastics Treaty will be enacted by 175 nations from 2025. The treaty is designed, among other things, to limit microplastic exposure globally. Burdens are greatest especially in children and especially those in low-middle income nations.

In Australia, legislation ending single use plastics will help. So too will the increased rollout of container deposit schemes that include plastic bottles.

Microplastics pollution is an area that requires a collaborative approach between researchers, civil societies, industry and government. We believe the formation of a “microplastics national council” would help formulate and co-ordinate strategies to tackle this issue.

Little things matter. Small actions by individuals can also translate to significant overall environmental and human health benefits.

Choosing natural materials, fabrics, and utensils not made of plastic and disposing of waste thoughtfully and appropriately – including recycling wherever possible – is helpful.

Mark Patrick Taylor, Chief Environmental Scientist, EPA Victoria; Honorary Professor, School of Natural Sciences, Macquarie University and Scott P. Wilson, Research Director, Australian Microplastic Assessment Project (AUSMAP); Honorary Senior Research Fellow, School of Natural Sciences, Macquarie University

This article is republished from The Conversation under a Creative Commons license. Read the original article.