Sparkling mineral water with 7% freshly squeezed organic pink grapefruit juice, grapefruit zest extract and organic hibiscus extract. Naturally cloudy, with pulp. 3 kcal per 100 ml.
IMPORTANT: grapefruit interacts with a great many medicines
This is not a general caution and it is the reason it is at the top of the page.
Grapefruit contains furanocoumarins, which irreversibly inhibit the enzyme CYP3A4 in the gut wall. That enzyme breaks down a large number of medicines before they reach the bloodstream. Block it, and considerably more of the drug is absorbed than the dose intended — in some cases several times more.
The effect can last more than 24 hours, so spacing the drink away from a tablet does not solve it. Affected medicines include several statins, some calcium channel blockers for blood pressure, certain immunosuppressants, some antiarrhythmics, some anxiolytics and some antihistamines.
Around a hundred medicines are known to interact and several dozen can do so seriously. If you take any prescription medicine, check with a pharmacist before drinking grapefruit regularly — it takes them two minutes, and grapefruit is one of the few genuinely well-established food-drug interactions in medicine.
At 7% juice this is a diluted grapefruit, not a glass of it. That reduces the concern; it does not remove the reason to ask.
The idea
Water with a splash of grapefruit, made portable. No sugar, no sweetener, no flavouring, no colour. The soft drinks aisle offers sweet drinks or plain water and very little in between; this is the in-between.
Why the zest extract matters
Almost all of a citrus fruit's aroma lives in the peel, not the juice. The juice gives acidity; the oil glands in the zest hold the aromatic compounds your nose actually reads as grapefruit. Using both is the difference between a drink that tastes of the fruit and one that tastes of acid.
The hibiscus
There for colour and for a tart edge — hibiscus is genuinely acidic, with malic and citric acid, and it deepens the pink. Worth knowing that hibiscus has been shown in trials to lower blood pressure modestly, which is relevant if you already take medication for it.
A labelling error, flagged
The nutrition footnote reads "*Calorie-free: >4kcal / 100ml". The symbol is reversed: the EU threshold for an energy-free claim is no more than 4 kcal per 100 ml, so it should read "<". At 3 kcal per 100 ml the drink comfortably meets the threshold — the claim is correct and only the symbol is wrong. We have flagged it to the producer.