Fresh fruit juice has become increasingly popular in many diets - especially among those consumers who are pressed for time and concerned about their health. Fruit juice has also been linked to beliefs that it can help people lose weight. But is juicing really as healthy as we think?
A recent study reveals hard truths about fruit juice.
All fruits contain sugars and don't seem to have harmful effects unless they contribute to extra daily calories. This is because the fiber (纤维) which is found in whole fruit is undamaged, and the sugar is contained within the fruit's cells. It takes our digestive system a while to break these cells down and for sugar to enter the bloodstream.
This is not the case with fruit juice. Different from whole fruit, the natural sugar in fruit juice counts as "free sugars", just like honey and added sugars. With the fiber removed, fruit juice's sugar is absorbed more quickly. A sudden rise of blood sugar causes the pancreas (胰腺) to release insulin (胰岛素) to bring it back down to a normal level. Over time, this system can wear out, increasing the risk of developing type-2 diabetes (糖尿病).
In 2013, after analysing the health data of 100,000 people collected between 1986 and 2009, researchers found that fruit juice consumption was linked with increased risk of type-2 diabetes. They've concluded that even when fruit juice is similar in the nutrition (营养) to whole fruit, fruit juice leads to faster and larger changes in insulin levels since liquids pass through the stomach faster than solids.
"Although fruit juice is better than no fruit at all, there are lots of limits," said Dr.Amy Smith, professor of medicine at the University of Virginia. "It particularly comes with risks when we consume more than 150 ml of free sugars per day, or when it puts us over our recommended calorie intake. It provides us with vitamins - but fruit juice is far from a quick fix."
