Vegetables are high in fiber and nutrients, especially if eaten raw
Vegetables may be good for your health, but eating a lot of them is unlikely to reduce the risk of heart attack or stroke, according to a large UK study.
What else we eat, how much exercise we do, and where and how we live may have a bigger impact, researchers say.
They point out, however, that a balanced diet helps reduce the risk of many diseases, including certain cancers.
Eating at least five servings of fruit and vegetables a day is recommended by health advisers, including the NHS.
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As part of the study, the universities of Oxford and Bristol and the Chinese University of Hong Kong asked almost 400,000 people taking part in the UK Biobank study to complete a questionnaire about their diet, including the amount of cooked and raw vegetables they consume each day.
On average, respondents report eating two heaping tablespoons of raw vegetables, three of cooked vegetables, and five total per day.
Their condition, as well as any heart problems that led to hospital treatment or death, was then tracked for the next 12 years.
Rich in fiber
Although the risk of dying from cardiovascular disease was about 15% lower in people who ate the most vegetables – particularly those who ate a lot of raw vegetables – compared to those who ate the least, researchers said it could be explained by other factors.
The researchers said that other factors could explain this phenomenon, including people’s lifestyle – for example, whether they smoke or drink alcohol – as well as their occupation, income and general diet.
As a result, they said their study found no evidence of a “protective effect of vegetable consumption” on the frequency of heart and circulatory problems.
Dr Ben Lacey, from the University of Oxford, says: “This is an important study that has implications for understanding the dietary causes of cardiovascular disease (CVD).”
But Professor Naveed Sattar, professor of metabolic medicine at the University of Glasgow, said there was “good trial evidence” that eating high fiber foods, such as vegetables, “can help reduce weight and improve levels of risk factors known to cause heart disease.”
He says the study’s findings are up for debate and shouldn’t alter widely held advice to eat at least five servings of fruit and vegetables a day.
“Unfortunately, many people living in the UK are falling short of this target and more needs to be done to encourage better vegetable consumption,” he says.
“In fact, I think we may have underestimated the importance of healthy diets on health and disease in general,” he adds.
Other experts have said measuring the amount and type of food people eat over many years to study the effect on disease risk is prone to error.
“Unfortunately, the reliability of the results obtained using simple questions asking users to express an average intake value should be questioned,” says Professor Janet Cade, from the University of Leeds.
The study, published in Frontiers in Nutrition, indicates that people who eat lots of raw vegetables may have a reduced heart risk because cooking vegetables removes important nutrients, such as vitamin C. The oils and fats used for cooking can have a negative effect on health.
Oils and fats used for cooking can also increase sodium and fat intake, which are known risk factors for heart problems.
People who eat a diet rich in vegetables may consume fewer calories and less fat, while consuming more vitamins and antioxidants, which can prevent cell damage.
