Are veggies key to heart health? Large new study says no, but they have plenty of other benefits

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  • A vegetable-rich diet doesn't reduce one's risk of cardiovascular disease, according to a new study.
  • The researchers say earlier studies suggesting the opposite, are likely to be biased.
  • However, this doesn't mean people should stop eating their veggies.

Exposure to vegetables begins at a very young age, with parents often bribing their children to consume these despised items on their plates. 

But a veggie-packed diet may not live up to all the hype. The findings of a recent study suggest that eating vegetables does not protect against cardiovascular disease (CVD), which can lead to heart attack, stroke, and death. 

The large-scale study, published in Frontiers in Nutrition, was based on an analysis of the diets of nearly 400 000 British adults.

Interestingly, raw vegetables were believed to offer better heart benefits than cooked vegetables. However, when the team accounted for lifestyle factors, including physical activity, smoking, alcohol, fruit, and red and processed meat consumption – as well as the use of vitamin and mineral supplements – the heart-related health benefits were no longer seen.

The  researchers are from the University of Oxford, the Chinese University of Hong Kong, and the University of Bristol. 

Data from UK Biobank

The consumption of vegetables has long been thought to lower the risk of cardiovascular disease as their ingredients, such as carotenoids and alpha-tocopherol, contain properties that could protect against CVD. But evidence from earlier studies has been inconsistent.

“The UK Biobank is a large-scale prospective study on how genetics and environment contribute to the development of the most common and life-threatening diseases,” professor Naomi Allen, UK Biobank’s chief scientist and study co-author said in a news release.

For their study, Allen and colleagues made use of the UK Biobank’s large sample size and long-term follow-up, and detailed information on participants' social and lifestyle factors, to reliably determine the link between vegetable consumption and the risk of subsequent CVD. 

The UK Biobank follows the health of half a million adults in the UK by linking to their healthcare records. Participants were interviewed about, among other factors, their diet, lifestyle, medical, and reproductive history.

Conducting the study

Of the nearly 400 000 participants, 4.5% went on to develop CVD. The researchers asked all participants about their daily average consumption of uncooked versus cooked vegetables. 

They then studied the association of vegetable consumption with the risk of hospitalisation or death from heart attack, stroke, or major CVD. The risk of dying from CVD was around 15% lower for people who had the highest vegetable intake. This apparent effect was, however, significantly reduced when possible socioeconomic, nutritional, and health- and medicine-related confounding factors were considered.

Bias in earlier studies

“Our large study did not find evidence for a protective effect of vegetable intake on the occurrence of CVD,” said co-author Dr Qi Feng from the Nuffield Department of Population Health at Oxford University. 

He went on to explain: 

Instead, our analyses show that the seemingly protective effect of vegetable intake against CVD risk is very likely to be accounted for by bias from residual confounding factors, related to differences in socioeconomic situation and lifestyle.

Feng and colleagues also suggested that additional research should further assess whether particular types of vegetables, or the way they are prepared, for example, might affect a person’s CVD risk.

Don’t neglect your veggies

In spite of the findings, eating a balanced diet and maintaining a healthy weight remains a critical part of maintaining good health and reducing one’s risk of major diseases, including some cancers, said co-author, Dr Ben Lacey, associate professor in the department at Oxford University.

“It is widely recommended that at least five portions of a variety of fruits and vegetables should be eaten every day,” he said.

Besides, there are several other proven, indisputable benefits of eating your greens, including lowering the risk of digestive problems and common ageing-related eye diseases, preventing some types of cancer, and supplying fibre, which has been linked to a lower incidence of obesity.

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