Orange juice contains the same quantity of fructose as Coca-Cola per 250ml serving, approximately 25 to 30 grams of sugar. The difference between eating an orange and drinking orange juice is the fibre matrix of the whole fruit. In the intact fruit, fructose is contained within plant cells surrounded by pectin, cellulose, and other fibre structures that slow its release and absorption. In juice, this matrix is absent, and the fructose is absorbed rapidly, producing a blood glucose and liver fructose load similar to a soft drink.
The Research Evidence
A large meta-analysis of prospective cohort studies published in BMJ found that consumption of whole fruit was associated with a significantly lower risk of type 2 diabetes, while fruit juice consumption was associated with a significantly higher risk. Three portions of whole fruit per week produced an 18 to 23 percent lower diabetes risk for specific fruits including blueberries, grapes, and apples. One portion of fruit juice per day was associated with an 8 percent higher diabetes risk.
What to Do Instead
Eat whole fruit rather than drink it. If a smoothie is desired, blend whole fruit including the fibrous parts rather than juicing, and include vegetables to reduce the sugar concentration. If fruit juice is consumed, limit it to 150ml per day, which is the portion cited in dietary guidelines, and pair it with a protein or fat source to blunt the glycaemic response. Water, sparkling water with lemon, and herbal teas are better default beverages than fruit juice at any quantity.