Known as "liquid gold", mānuka honey can cost as much as £100 (NZ$192) a jar and celebrities including Gwyneth Paltrow and Scarlett Johansson have sworn by its healing powers.
The honey, made from bees that pollinate the mānuka bush in New Zealand, has antibacterial properties and contains a host of nutrients including amino acids, B vitamins and calcium. It has been shown to help wounds heal and has long been used to help sore throats, skin conditions and digestive problems.
New Zealand has brought in controls to ensure only genuine mānuka honey can be exported, but experts fear some jars are being tampered with before they reach Britain.
Holland & Barrett boss Peter Aldis said: "If you're buying mānuka honey you want to be sure what you're getting is the real deal. We've decided to adopt New Zealand government requirements in the UK to ensure our customers only get the purest, strongest, undiluted manuka honey, where antibacterial strength is measured and presented in a robust and transparent way."
From tomorrow, all 34 types of mānuka honey sold in the chain's 750 stores will be quality tested.
Honey expert Dr Adrian Charlton, of food and plant laboratory Fera, is leading the testing. His team will measure the levels of methylglyoxal, or MGO, in each batch — an indicator of the honey's antimicrobial strength.
Only honeys containing 40 MGO to 850 MGO will be allowed to go on sale.
"It comes down to an issue of quality," said Dr Charlton.
"People are buying mānuka honey because they think it will make them feel better and that's related to the antimicrobial strength."
