Why you should never drink fruit juice at breakfast

• Juice contains lots of the sugar fructose, which reaches the small intestine fast
• After periods without food, the small intestine is unable to process fructose
• It then 'spills over' into the large intestine, which contains 'good bacteria'
• Such bacteria is not designed to process sugar, with an effect being 'likely'
• Researchers advise people limit their sweet intake to small amounts after meals

Scientists have suggested why people should never drink fruit juice at breakfast.

Consuming OJ on an empty stomach 'overwhelms' the digestive system and may disrupt beneficial gut bacteria, a US study implies.

Fruit juice contains high levels of the sugar fructose, which is quick to reach the small intestine after consumption, the researchers found.

Following periods of 'fasting', such as in the mornings, the organ is unable to process large amounts of fructose, causing it to 'spill over' into the large intestine, the research adds.

Once in the large intestine, fructose comes into contact with 'good bacteria', which are not designed to process sugar, according to the researchers.

Although the results did not reveal if this has a negative health impact, the scientists believe 'an effect is likely'.

They therefore advise people stick to 'the most old-fashioned advice in the world' by 'limiting sweets to moderate quantities after meals'.

Consuming OJ on an empty stomach 'overwhelms' the digestive system (stock)

SHOULD YOU DRINK BEETROOT JUICE BEFORE EXERCISE?

Drinking beetroot juice before exercise could take years off your brain, research suggested in April 2017.

Combining the drink with exercise strengthens certain regions of the brain, making it appear more youthful and potentially preventing the organ's decline, a study found.

This finding could help people who are at risk of brain deterioration to remain functionally independent, such as those with a family history of dementia, according to the researchers.

Drinking beetroot juice before exercise could take years off your brain

Beetroot juice's power likely lies in its nitric-oxide content, with past research suggesting this both increases blood flow to the brain and improves exercise performance.

Study author Professor Jack Rejeski, from Wake Forest University, North Carolina said: 'Nitric oxide is a really powerful molecule. It goes to the areas of the body which are hypoxic, or needing oxygen, and the brain is a heavy feeder of oxygen in your body.

'Compared to exercise alone, adding a beetroot juice supplement to exercise resulted in brain connectivity that closely resembles what you see in younger adults.'

The researchers analysed 26 men and women aged 55 and over who did not exercise and had high blood pressure.

Some participants were given beetroot juice one hour before walking for 50 minutes on a treadmill, while others did the same exercise but without the drink. This was repeated three times a week for six weeks.

'Limit sweets to moderate quantities after meals'

Although past studies suggest sugar is processed by the liver, the new research implies more than 90 percent of fructose is digested in the small intestine.

Results further show the small intestine is better able to process fructose when it is consumed after a meal.

Study author Professor Joshua Rabinowitz from Princeton University, said: 'We saw that feeding mice prior to sugar exposure enhanced the small intestine's ability to process fructose and that protected the microbiome from sugar exposure.'

The researchers add the findings support 'the most old-fashioned advice in the world,' which is to 'limit sweets to moderate quantities after meals'.

How the research was carried out;

The researchers fed mice a 1:1 mixture of fructose:glucose.

They then followed how the sugars were processed in the animals' digestive tracts.

The findings were published in the journal Cell Metabolism.

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