Millions of us rely on a cup of coffee for an energy hit first thing in the morning.
But experts say enjoying the drink at this time of the day could come with unfortunate health risks.
The can stimulate the stomach to produce more acid, leading to reflux symptoms including heartburn, nausea, bad breath and bloating.
Yet, medics say this can be easily solved by eating food at the same time as indulging in your morning brew.
Dr Masarat Jilani, a London-based NHS GP and resident doctor for supplement provider Jude, said: ‘As we get older, our gut can become more sensitive.’
Having coffee first thing in the morning without eating beforehand could ‘irritate the gut and ramp up acid production’, leading to acid reflux.
Acid reflux is caused by stomach acid flowing into the oesophagus — the tube that connects the mouth and the stomach — irritating the soft tissue.
Research has long shown caffeine stimulates the production of the hormone gastrin, which is responsible for our gastric acid production.

Relying on a cup of coffee first thing in the morning can stimulate the stomach to produce more acid, leading to reflux symptoms including heartburn, nausea, bad breath and bloating

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Although this helps kick start the process of digestion, it also adds acidity to the stomach.
Plant-based compounds known as phenols, which are also abundant in coffee, can contribute to the gut’s level of acidity.
One 2022 study by researchers in France found coffee may relax the esophageal sphincter, ‘allowing food to escape into the oesophagus and cause heartburn’.
The effects can vary from person to person.
For some the higher levels of gastric acid caused by drinking coffee without food, won’t cause any problems, but for others it leads to discomfort.
To prevent acid reflux, Dr Jilani also recommends waiting at least an hour after waking before reaching for a coffee.
She told The Mirror that this gives enough time for hormone levels that regulate digestion to rebalance, and gives you a chance to eat something.
‘Plus, spacing out your caffeine intake can lead to more stable energy levels throughout the day, rather than the sharp highs and crashes that come with an early caffeine hit.’
Around a quarter of people in the UK suffer from reflux.
Other common symptoms include a chronic cough — that persists longer than eight weeks — frequent throat-clearing, hoarseness and a sore throat.
Often, someone with these symptoms won’t realise they have reflux because the oesophageal tissues have likely been exposed to acid for so long, they’ve been numbed to its effects.
These ‘silent’ symptoms mean the condition can be overlooked, which has its own risks: a growing number of people are now succumbing to oesophageal cancer — the most extreme manifestation of acid damage.