You've probably heard of the 5 A DAY advice: you should eat at least five portions of fruit and veg daily to help stay healthy.
Fruit juice is often counted as one of those portions, but a top health expert has now said it shouldn't.
Dr Susan Jebb is a health adviser to the government and she's an expert on diet and obesity.
She said: "Fruit juice isn't the same as intact fruit and it has got as much sugar as many classical sugar drinks."
Dr Jebb also says that because the sugar in fruit juice is absorbed very fast, "by the time it gets to your stomach your body doesn't know whether it's Coca-Cola or orange juice".
She said if people want to drink orange juice they should drink smaller amounts, diluted with water, to reduce the amount of sugar they drink.
Dr Jebb said eating fruit whole - like an apple or an orange - is much better for you because you will be getting more nutrients, more fibre and will be eating less sugar than you would if you had a juice.
But the Department of Health says that even though fruit juice has natural fruit sugars, the benefits of drinking it are more than the negatives.
Why 5 A DAY?
5 A DAY is based on advice from the World Health Organization, which recommends eating a minimum of 400g of fruit and vegetables a day to lower the risk of serious health problems, such as diabetes and obesity.
Fruit and vegetables are a good source of vitamins and minerals, including vitamin C, and they're a source of dietary fibre, which helps keep your insides healthy.