Diet drinks don't do your heart any favours

  • French researchers found that regular consumers of diet drinks had a higher risk of heart disease and stroke
  • They appeared to more likely to develop cardiovascular disease than people who regularly drank sugary drinks
  • They could, however, not place the blame on artificial sweeteners as such

Replacing sugary drinks with diet versions may not be any healthier for the heart, a large, new study suggests.

French researchers found that people who regularly drank artificially sweetened beverages had a higher risk of heart disease and stroke, versus people who avoided those beverages. In fact, they were no less likely to develop cardiovascular disease than people who regularly downed sugary drinks.

The findings do not pin the blame on artificial sweeteners, per se, one expert said. People who use them may have an overall diet, or other lifestyle habits, that raise their risk of heart trouble.

"This doesn't indicate that artificially sweetened beverages caused the increased risk of cardiac events," said Colleen Rauchut Tewksbury, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics.

'Just one component'

Cutting down on added sugar is definitely a good thing, said Tewksbury, who was not involved in the study.

And if diet drinks help people do that, she added, then they can be a positive replacement.

But, Tewksbury stressed, that's "just one component" of a whole diet: If people switch to zero-calorie sodas, then eat extra fries or indulge in dessert, the effort is lost.

The findings, published online on 26 October as a research letter in the Journal of the American College of Cardiology, are based on over 100 000 French adults taking part in an ongoing nutrition and health study.

Starting in 2009, the participants completed diet surveys every six months, reporting on what they'd consumed over the past 24 hours. Based on those records, researchers divided them into six groups: non-consumers, low consumers and high consumers of sugar-sweetened and artificially sweetened drinks.

Tough to draw conclusions

Over a decade, 1 379 study participants suffered a first-time heart attack, severe chest pain or stroke. And on average, the risk was 32% higher among high consumers of diet drinks, versus non-consumers. The risk among high consumers of sugary drinks was 20% higher.

Of course, people might choose diet beverages because they need to lose weight, or manage a health problem, acknowledged the researchers – led by Eloi Chazelas, of Sorbonne Paris Nord University.

So the investigators accounted for participants' self-reported eating habits, as well as exercise levels, smoking and conditions like high blood pressure and diabetes.

And diet drinks were still tied to a heightened risk of cardiovascular trouble, though the study did not prove that diet drinks caused heart problems.

However, Tewksbury said it's difficult to fully account for all the diet and lifestyle factors that might be behind the link. She also pointed to the numbers: Only 56 "high consumers" of diet drinks suffered heart problems or stroke – and that also makes it tough to draw conclusions.

Importance of nutrition

The Calorie Control Council, which represents the low-calorie food industry, also took issue with the findings.

"Epidemiological studies, even those built on large sample sizes, are subject to potential pitfalls including reverse causality [subjects choose low and no-calorie sweeteners (LNCS) as a tool to manage their weight after becoming overweight/obese] and residual confounding [inability to control for factors that influence health outcomes], as the researchers noted," the council said in a statement.

Dr Andrew Freeman is a cardiologist at National Jewish Health, in Denver. In his own practice, he emphasises the importance of nutrition in helping to prevent and manage heart disease.

Freeman said it's possible artificial sweeteners, themselves, have a negative effect on heart health. Some research, for example, suggests they can trigger an insulin "response", he noted. Insulin is a hormone that regulates blood sugar.

"At the end of the day, the best calorie-free beverage is water," Freeman said.

Best to limit food additives

Not everyone loves water, he acknowledged, and some people are attached to the sweet taste and bubbles of their favourite drink. "It's hard for people to give up their diet soda," Freeman said. "It can be pretty addictive."

But it's best to limit food additives, according to Freeman – not only in drinks, but also in processed foods in general. "If you can't pronounce the ingredients on the label, that's a red flag," he added.

Freeman, who has been dubbed "the vegan cardiologist", recommends eating mostly plant-based, whole foods – fruits and vegetables, beans and legumes, whole grains and nuts. That type of diet has proven heart benefits, he said.

Image credit: iStock

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