Eating vegetables does not protect against cardiovascular disease, finds large-scale study

A sufficient intake of vegetables is important to maintain a balanced diet and prevent a wide range of diseases. But could a diet rich in vegetables also reduce the risk of cardiovascular disease (CVD)? Unfortunately, researchers from the Nuffield Department of Population Health at the University of Oxford, the Chinese University of Hong Kong, and the University of Bristol found no evidence of this.

That the consumption of vegetables can reduce the risk of CVD might seem plausible at first glance, since its ingredients, such as carotenoids and alpha-tocopherol, have properties that could protect against CVD. But so far, evidence from previous studies of an overall effect of vegetable CVD consumption has been inconsistent.

Now, new results from a powerful new large-scale study in Frontiers in Nutrition shows that higher consumption of cooked or raw vegetables is unlikely to affect CVD risk. They also explain how confounding factors could have explained earlier false-positive findings.

“The UK Biobank is a large-scale prospective study of how genetics and the environment contribute to the development of the most common and life-threatening diseases. Here we use the UK Biobank’s large sample size, long-term follow-up deadline and detailed information on social issues and lifestyle factorsto reliably assess the association of vegetable intake with subsequent CVD risk,” said Professor Naomi Allen, UK Biobank’s Chief Scientist and co-author of the study.

The UK Biobank tracks the health of half a million adults in the UK by linking to their healthcare records. Upon enrollment in 2006-2010, these volunteers were interviewed about their diet, lifestyle, medical and reproductive history, and other factors.

The researchers used responses at enrollment from 399,586 participants (of whom 4.5% developed CVD) to questions about their average daily consumption of raw versus cooked vegetables. They looked at the association with the risk of hospitalization or death from myocardial infarction, stroke, or major cardiovascular disease. They controlled for a wide range of potential confounders, including socio-economic statusphysical activity and other dietary factors.

Crucially, the researchers also tested the potential role of “residual confounding,” that is, whether additional unknown factors or inaccurate measurement of known factors could lead to a false statistical association between CVD risk and alcohol consumption. vegetables.

The mean daily intake of total vegetables, raw vegetables, and cooked vegetables was 5.0, 2.3, and 2.8 heaping tablespoons per person. The risk of dying from CVD was about 15% lower for those with the highest intake compared to the lowest intake of vegetables. However, this apparent effect was substantially weakened when potential socioeconomic, nutritional, and health and medical-related confounders were taken into account. Controlling for these factors reduced the statistical predictive power of vegetable intake on CVD by more than 80%, suggesting that more precise measures of these confounders would have fully explained any residual effect of vegetable intake.

Dr Qi Feng, a researcher at the Nuffield Department of Population Health at the University of Oxford and lead author of the study, said: “Our large study found no evidence of a protective effect of vegetable intake on the occurrence of CVD. Instead, our analyzes show that the apparently protective effect of vegetable intake against CVD risk is most likely due to bias from residual confounders, related to differences in socioeconomic status and lifestyle. lifetime”.

Feng et al. they suggest that future studies should further assess whether certain types of vegetables or their method of preparation might affect CVD risk.

The last author, Dr Ben Lacey, Associate Professor in the Oxford University department, concluded: “This is an important study with implications for understanding the dietary causes of CVD and the burden of CVD that is normally attributed to obesity. low intake of vegetables.However, eating at balance diet and maintaining a healthy weight remains an important part of maintaining good health and reducing the risk of major diseases, including some types of cancer. It is highly recommended that at least five servings of a variety of fruits and vegetables be consumed each day.”