The "five a day" rule should be doubled to 10 pieces of fruit and vegetables, a major study has said as it found that increasing consumption dramatically decreases the chance of disease.
The new research, led by scientists from Imperial College London and published in the International Journal of Epidemiology, analysed 95 studies on fruit and vegetable intake.
Dr Dagfinn Aune, lead author of the research from the School of Public Health at Imperial said:
“We wanted to investigate how much fruit and vegetables you need to eat to gain the maximum protection against disease, and premature death. Our results suggest that although five portions of fruit and vegetables is good, 10 a day is even better.”
Fruit and veg have a complex network of nutrients
Fruit and vegetables have been shown to reduce cholesterol levels and blood pressure while boosting the health of blood vessels and the immune system, Dr Aune said.
“This may be due to the complex network of nutrients they hold. For instance they contain many antioxidants, which may reduce DNA damage, and lead to a reduction in cancer risk.
The study, which was a meta-analysis of all available research in populations worldwide, included up to 2 million people, and assessed up to 43,000 cases of heart disease, 47,000 cases of stroke, 81,000 cases of cardiovascular disease, 112,000 cancer cases and 94,000 deaths.
The results revealed that a daily intake of 200g was associated with a 16% reduced risk of heart disease, an 18% reduced risk of stroke, and a 13% reduced risk of cardiovascular disease. This amount, which is equivalent to two and a half portions, was also associated with 4% reduced risk in cancer risk, and 15% reduction in the risk of premature death.
However eating up to 800g fruit and vegetables a day, or 10 portions, was associated with a 24% reduced risk of heart disease, a 33% reduced risk of stroke, a 28% reduced risk of cardiovascular disease, a 13% reduced risk of total cancer, and a 31% reduction in dying prematurely.
Fruit and veg beneficial despite other lifestyle factors
In the analysis, the team took into account other factors, such as a person's weight, smoking, physical activity levels, and overall diet, but still found that fruit and vegetables were beneficial.
The research team found that apples and pears, citrus fruits, salads and green leafy vegetables such as spinach, lettuce and chicory, and cruciferous vegetables such as broccoli, cabbage and cauliflower may help protect against heart disease, stroke, cardiovascular disease, and early death. And cancer risk could be reduced by eating green vegetables, such as spinach or green beans, yellow vegetables, such as peppers and carrots, and cruciferous vegetables.
The researchers said that compounds called glucosinolates in cruciferous vegetables such as broccoli and cabbage activate enzymes that may help to prevent cancer, and that fruit and vegetables might have a beneficial effect on naturally occurring bacteria in the gut.
Fewer than a 1/3 of British adults thought to meet 5 a day target
Fewer than a third of British adults are thought to meet even the present target of 5 a day or 400g.
One portion or 80g of fruit is equivalent to about one apple, banana or pear, two plums or satsumas, or half a grapefruit.
Three heaped tablespoons of cooked vegetables such as carrots, peas, or sweetcorn count as one portion, as do two broccoli spears or four heaped tablespoons of cooked kale or spinach.
Unsweetened fruit juice, vegetable juice or smoothies can only ever count as one of your five a day. Beans and pulses also count as one portion per day, regardless of how much you eat.
The advice from the authors is that if people are struggling to eat five a day, they could consider concentrating on the types of fruit and vegetables associated with reduced risk, according to the research.
Sarah Toule, from the World Cancer Research Fund, said:
“This interesting research shows just how incredibly important vegetables and fruit are as part of a healthy diet. In fact, they’re essential for maintaining a healthy weight, which our own evidence has shown reduces the risk of 11 common cancers.
“People should aim to eat at least five portions of vegetables and fruit a day but the more the better. If people find this hard, why not start by adding an extra portion of fruit or veg a day to your lunch or try swapping one of your naughty snacks for a piece of fruit?”