Eating fruit and drinking fruit juice may have very different effects on type 2 diabetes risk
A new study suggests that eating certain types of fruit may help protect against type 2 diabetes, but that drinking fruit juice could increase your risk.
BMJ Group News
What do we know already?
Fruits provide us with fibre, antioxidants, and chemicals (called ‘phytochemicals’) that scientists believe can help prevent strokes and diseases such as cancer. But previous studies examining relationships between eating fruit and a risk of diabetes have given mixed results. This might have been because of the differences in the types of fruit used in the studies. So, in this new study, the researchers wanted to see what effects individual fruits might have on the risk of type 2 diabetes.
The researchers looked at the results of three large studies that followed a total of about 187,000 people over several years. The people in the study filled in questionnaires on how often they ate specific kinds of fruit. These were: grapes or raisins, peaches, plums or apricots, prunes, bananas, cantaloupe, apples or pears, oranges, grapefruit, strawberries, and blueberries. The researchers also looked at how much fruit juice people drank. They then looked at how many people developed type 2 diabetes during the study, and whether there was any link to how much fruit and fruit juice they consumed.
Overall, about 6 in 100 people developed type 2 diabetes during the study. The study found that eating fruit generally reduced the risk of developing the disease, and that different fruits produced different reductions in risk. The fruits that reduced type 2 diabetes risk the most were blueberries (which reduced the risk by 26 percent), grapes and raisins (12 percent), and apples and pears (seven percent). However, drinking fruit juice increased people’s risk of type 2 diabetes by about eight percent. Scientists think this is because drinking fruit juice allows more sugar to get into our blood much faster than eating the whole fruit.
How reliable is the research?
This study was what’s called a systematic review, which is a type of study that tries to pool the results of smaller studies in order to get a more accurate ‘big picture’. It looked at results from three studies that, between them, covered the years from 1984 to 2009. The studies took place in the UK, the US, and Singapore.
But using questionnaires to record people’s eating habits means that researchers can never be completely sure that the people remembered their diets correctly, or that they were honest about their diets. So there is always some uncertainty.
It’s also possible that the people in the study who ate plenty of fruit led more generally healthy lifestyles that made them less likely to get type 2 diabetes. Studies like this one try to allow for things like this in their calculations, but we don’t know how accurate they can really be. So, while these results are interesting, it’s uncertain whether a study like this can show accurately that a specific type of food can have a specific effect on our health.
What does this mean for me?
Even though we can’t be sure about the specific findings of this study, it should come as no surprise that it found that eating fruit (as opposed to drinking fruit juice) can have health benefits. Fruit is an essential part of a healthy diet. The World Health Organization recommends that everyone should try and eat five portions of fruit or vegetables a day. So whether you’re worried about getting diabetes or you just want to be healthy, eating more fruit certainly can’t hurt.
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