The new store in Chester, northwest England, is the first of 50 Holland & Barrett More outlets planned for the next two years, stocking 700-plus products free of ingredients such as gluten, nuts and eggs among others.
Holland & Barrett, the British arm of U.S. nutritional supplements and wellness products company NBTY [CRLYNY.UL], already trades from more than 620 outlets across the UK and Ireland and is aiming to become Britain's largest "free from" retailer.
The company's website will initially offer 1,000 products, expanding to more than 3,000 by the end of the year, covering all of the main "free from" categories.
Research company Mintel says the British market for such products doubled in value from 2009 to reach 365 million pounds ($549 million) last year and is forecast to grow by a further 50 percent by 2019.
Rival researcher YouGov said that a 2014 survey found that 22 percent of people in the UK consider themselves to have a food allergy or intolerance, up 5 percent since a 2011 survey.
"The speed of growth of 'free from' has seen it transform from what was once regarded as a nutritional niche into a mainstream shopping option," NBTY's European CEO Peter Aldis said.
The boom in "nutraceuticals" -- food and drink with potential health benefits -- is also paving the way for a rush of marger and acquisition activity as food and drug companies compete to dominate a market expected to be worth $280 billion by 2018.
(Reporting by James Davey; Editing by David Goodman)