Eating sufficient amounts of vegetables might be good for overall health, but surprising results from a study suggested that their inclusion in the diet might have little or no effect on the risk of developing cardiovascular disease (CVD).
An investigation, led by the Nuffield department of population health at the University of Oxford, found that They said their findings, published in the journal Frontiers in Nutrition might mean that advice on vegetable intake and heart disease in high-income countries should be reappraised.
Teresa Burton/MDedge News
However, leading experts commented that the findings confirmed that higher overall vegetable consumption did lower the risk of cardiovascular disease.
UK Biobank data
Boosting health through a diet rich in vegetables has been backed by a large body of evidence, with guidelines consistently recommending them as a valuable source of macronutrients and micronutrients, such as dietary fiber, vitamins, and phytochemicals. However, the research team, which included the Chinese University of Hong Kong and the University of Bristol, set out to probe the independent effects of cooked and raw vegetables on health outcomes. Previous epidemiological studies had demonstrated inconsistent findings, they said.
They based their research on 399,586 people with no history of angina, stroke, and myocardial infarction, who enrolled in the UK Biobank. Of those, 55.4% were women, and 90.9% were of White ethnicity. The average body mass index was 27.3.
Raw and cooked vegetables
From their enrollment questionnaire, the mean intake of vegetables was found to be 2.3 heaped tablespoons per day of raw vegetables, and 2.8 of cooked vegetables. During an average follow-up of 12.1 years, 4.5% of the participants went on to develop CVD.
There was an inverse association between incident CVD and total and raw vegetable intake, but not cooked vegetable intake. Those who ate the most vegetables – both cooked and raw – had a 10% lower incidence of CVD, compared with those who ate the least. However, whereas raw vegetable intake was associated with an 11% reduction in CVD for those who ate the most, compared with the least, no reduction was seen for cooked vegetables.
Consuming two or more heaped tablespoons each day of cooked and raw vegetables was associated with a lower risk of dying from CVD, but little evidence was seen that a higher intake increased protection further. Similarly, there was evidence of an inverse association of CVD mortality with raw vegetable intake.
Researcher Qi Feng, from the Nuffield department of population health, said: “Our large study did not find evidence for a protective effect of vegetable intake on the occurrence of CVD. 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.”