Large-Scale Study Finds Eating Vegetables Does Not Protect Against Cardiovascular Disease

Sufficient intake of vegetables has long been recommended as part of a balanced and healthy diet to lower the risk of a multitude of diseases. However, a new study conducted by the Nuffield Department of Population Health at the University of Oxford, the Chinese University of Hong Kong, and the University of Bristol, did not find that a diet high in vegetables was effective in lowering the risk of cardiovascular disease (CVD).

The study authors noted that data gathered from prior research are inconsistent in illustrating the overall effect of vegetable consumption on CVD. However, the results from the current study, which was published in Frontiers in Nutrition, show that higher consumption of cooked or uncooked vegetables is unlikely to affect the risk of CVD.

“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. Here we make use of the UK Biobank’s large sample size, long-term follow-up, and detailed information on social and lifestyle factors, to assess reliably the association of vegetable intake with the risk of subsequent CVD,” said study co-author professor Naomi Allen, UK Biobank’s chief scientist, in a press release.

For the study, volunteers at the UK Biobank were interviewed from 2006-2010 about factors such as diet, lifestyle, medical, and reproductive history.

The investigators used the responses from 399,586 participants regarding their daily average consumption of uncooked versus cooked vegetables, analyzing the association with the risk of hospitalization or death from myocardial infarction, stroke, or major CVD. The investigators controlled for other potential confounding factors, such as socio-economic status and other dietary issues.

The study authors also sought to assess the potential role of “residual confounding,” which is whether other unknown factors or inaccurate measurement of known factors could cause a false statistical association between CVD risk and vegetable consumption.

The study found that the mean daily intake of total vegetables, raw vegetables, and cooked vegetables was 5.0, 2.3, and 2.8 heaped tablespoons per person, respectively. The risk of death from CVD was approximately 15% lower for those with the highest vegetable intake compared to the lowest vegetable intake.

However, this effect was significantly weakened when assessing other possible socio-economic, nutritional, and health- and medicine-related confounding factors. The study authors suggest that more precise measures of these cofounders may shed light on the residual effect of vegetable intake.

“This is an important study with implications for understanding the dietary causes of CVD and the burden of CVD normally attributed to low vegetable intake. However, eating a balanced diet and maintaining a healthy weight remains an important part of maintaining good health and reducing risk of major diseases, including some cancers. It is widely recommended that at least five portions of a variety of fruits and vegetables should be eaten every day,” said last author Dr Ben Lacey, an associate professor in the Nuffield Department of Population Health, in the press release.

REFERENCE

Eating vegetables does not protect against cardiovascular disease, finds large-scale study. Frontiers. February 21, 2022. Accessed February 25, 2022. https://blog.frontiersin.org/2022/02/21/frontiers-nutrition-cardiovascular-disease-risk-vegetable-intake-does-not-protect/