The surprising benefits of a glass of orange juice

The habit of drinking a glass of orange juice can have a considerable effect on your health.

If you’re anything like me, then your idea of breakfast heaven includes an ice-cold glass of freshly squeezed orange juice. The trouble is that this sweet citrus drink has been demonised for some time.

While oranges themselves are packed full of vitamins, in drink-form, experts warn that orange juice delivers a sudden rush of sugar to the blood. Over time, this daily sugar-spike could lead to insulin resistance, raising the risk of diabetes, heart disease and obesity.

Or so the thinking goes. Yet actually, research is starting to show that despite its high sugar content, a daily glass of orange juice could bring all manner of health benefits.

Why we got orange juice wrong

To begin with, cohort studies – which track tens of thousands of people over time – show that individuals who eat lots of citrus fruits are less likely to go on to suffer from heart disease and stroke.

However most of these large studies asked people about how much fruit they ate, not how much fruit juice they drank. Eating whole fruit can have a substantially different effect on the body compared with drinking fruit juice.

“First of all, it’s the speed of eating,” says Federica Amati, a nutrition scientist at Imperial College London, UK. Amati points out that if you eat two or three oranges – the average amount it takes to make a small glass of orange juice – “it’s going to take you longer to eat them, chew them and swallow them”.

She adds, “In fact, most people probably wouldn’t want to eat two or three, as that’s quite a lot of oranges. Whereas when you’re drinking a small glass – in a couple of seconds it’s gone.”

Whole fruit is also rich in fibre, which feeds the good bacteria in your gut, and is linked to health benefits such as a reduced risk of cardiovascular disease and colon cancer. Fibre also slows down the flow of sugars into our bloodstream. Orange juice – and other fruit juices – are made by crushing and pulping whole fruits, which strips them of most of their fibre.

The end result is that if you compared a person’s blood sugar response from eating a whole orange versus drinking a juice, the whole orange would result in a fairly gradual rise, whereas a glass of orange juice has a more dramatic effect.

“[In orange juice], the sugars have been freed from their fibre capsules, and so they are absorbed very rapidly in the mouth and in the stomach. So that will lead to quite a rapid, quick rise in blood sugar,” says Amati.

However for most people such a rise is not a problem, because insulin is released which then removes sugar from the bloodstream. However for someone with diabetes, a glass of OJ may not be such a good idea.

“I think the challenge with fruit juices generally is that they are technically free sugars, but that’s not all they are,” says Amati. “So yes, they do make your blood sugar go up, but – especially if they’re freshly squeezed – they also have bioactive nutrients in them like vitamin C. So it’s not about just freaking out because of the sugar, it’s really contextualising it into the whole diet.”

Heart and brain health

There are signs that frequent orange juice drinking could still confer benefits, despite high sugar content. For example one meta-analysis which pooled the results of 10 randomised controlled trials (RCTs) found that drinking 500ml (17 fl oz) of orange juice a day was associated with lower blood glucose levels, improved insulin function and lower levels of low-density lipoprotein (LDL), known as “bad cholesterol” – all signs of good heart health.

Another meta-analysis found that drinking a glass of orange juice every day for a matter of weeks was enough to lower systolic blood pressure in overweight and obese adults, as well as raise levels of high-density lipoprotein (HDL), often referred to as “good cholesterol”.

It isn’t just heart health; orange juice could be good for the brain too. In one trial, 24 healthy men aged between 30 and 45 drank either 240ml (8 fl oz) of 100% orange juice, or a sugary drink containing the same amount of calories. The participant’s mood and cognitive function were tested before and six hours after drinking the beverage. Not only did the mental faculties of the OJ group increase after gulping down the drink, their subjective feelings of alertness did too.

“For the placebo, what we saw is a decline [in cognitive performance] over the day, with a much worse performance after six hours,” says Daniel Lamport, associate professor of nutritional neuroscience at the University of Reading, UK, who led the study. “That’s what you normally see, as people tend to get more tired and fatigued throughout the day.”