A diet rich in fruit, vegetables and whole grains is linked to a lower risk of developing Type 2 diabetes, according to two new studies.
The papers, published in the British Medical Journal (BMJ), found that even a modest increase in these foods as part of a healthy diet could help prevent Type 2 diabetes, which is linked to obesity.
In the first study, researchers examined blood levels of vitamin C and carotenoids – plant pigments which give some fruit and vegetables their bright colour – as an indicator of fruit and vegetable intake.
Some 9,754 people with Type 2 diabetes were compared with a group of 13,662 people without the condition, all of whom were part of the European Prospective Investigation into Cancer and Nutrition (EPIC)-InterAct study in eight European countries.
The results showed that those with the highest intakes of fruit and veg had up to a 50 per cent reduced risk of diabetes compared to those with the lowest intakes.
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A score based on how much fruit and veg people ate was used to determine the risk between five separate groups.
Those in the lowest group typically ate 274g of fruit and veg per day, while those in the highest group ate almost twice this amount (508g per day), and had the most benefit – a 50 per cent reduction in Type 2 diabetes risk.
Eating 274g is about the weight of one medium banana, half a head of broccoli and a small handful of cherry tomatoes. Eating 508g is around the equivalent of a large banana, half a head of broccoli, a large handful of cherry tomatoes and a large handful of strawberries.
However, the researchers found that even those who ate less than 508g per day could lower their risk of diabetes by eating modest amounts more than what they were already doing.
The researchers calculated that every 66g per day increase in total fruit and vegetable intake was associated with a 25 per cent lower risk of developing Type 2 diabetes compared to what they were eating before.
The authors, who took factors such as lifestyle into account, concluded: “These biomarkers are objective indicators of fruit and vegetable consumption, and suggest that diets rich in even modestly higher fruit and vegetable consumption could help to prevent development of Type 2 diabetes.”
In the second study, researchers in the US, including from the Harvard school of public health, looked at whole grain intake and the risk of Type 2 diabetes. Their findings were based on data from 158,259 women and 36,525 men.
After adjusting for lifestyle and dietary risk factors for diabetes, those with the highest intake of whole grains had a 29 per cent lower rate of Type 2 diabetes compared with those who ate the least.
For individual whole grain foods, the researchers found that consuming one or more servings a day of whole grain cold breakfast cereal or dark bread was associated with a lower risk of Type 2 diabetes (19 per cent and 21 per cent respectively) compared with consuming less than one serving a month.
Eating two or more servings a week – when compared with less than one serving a month – was associated with a 21 per cent lower risk for oatmeal, a 15 per cent lower risk for added bran, and a 12 per cent lower risk for brown rice and wheat germ.
The researchers said the association between higher total whole grain intake and lower risk of Type 2 diabetes “was stronger in individuals who were lean than in those who were overweight or obese.”
They said the reduced risk held true even when other factors such as how much exercise people did were taken into account, alongside their family history of diabetes.
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Emma Elvin, senior clinical adviser at Diabetes UK, said: “While there are some risk factors for Type 2 diabetes you can’t change such as your age, ethnic background and family history, we know that around three in five cases can be prevented or delayed by making lifestyle changes such as adopting healthier eating habits, increasing activity levels and getting support to manage a healthy weight.
“These new research findings provide yet more evidence that eating plenty of fruit and vegetables, and choosing wholegrain foods, such as wholegrain breakfast cereals, oats, brown rice and wholemeal bread, is associated with a reduced risk of developing Type 2 diabetes.
“Even more encouraging, these studies show that it can take fairly small increases in consumption of such foods for them to be beneficial and to help reduce the risk.
“The 12.3 million people at increased risk of developing Type 2 diabetes in the UK should absolutely be supported to manage a healthy weight, get regular physical activity and eat healthy foods to help them reduce their risk of developing a condition that can sometimes have devastating consequences for those living with it.”
Reader Q&A: Can eating a lot of sugar really lead to diabetes?
Asked by: David Flint, Newcastle
Yes. Too many calories of any kind will lead to obesity, which increases your chance of developing diabetes. But a 2013 study at Stanford University found that adding 150 calories of sugar per day to your diet increases your diabetes risk by 1 per cent, even after accounting for obesity, physical activity and total calorie intake. So sugar calories are particularly harmful.