Waitrose will launch a major new grocery brand this month as the grocer continues to attempt to steal the march on its larger rivals.

The Waitrose "Love Life" brand, which will debut in stores later this month, is the grocer's biggest initiative since the successful "Essential Waitrose" in 2009 and aims to highlight "nutrient-packed" foods. The new brand's logo will also be stamped on other foods across the store to highlight their nutritional value.

Waitrose's marketing director, Rupert Thomas, said it was not a diet brand, but spelled a "new approach to healthy eating". "Usually this area is seen to be about restriction of choice but Love Life is about eating more variety and more of the right things."

The range was developed after customers complained of wanting to eat more wholefoods and less saturated fat. A blueberry, blackcurrant and beetroot smoothie and high-fibre white bread are among the first batch of 270 products that will start to arrive in stores from 30 June. Love Life will also have a quarterly magazine and a section on the retailer's website.

Waitrose uses chef Heston Blumenthal and cookery writer Delia Smith to endorse its products and a new "face" is expected to front the brand, although Thomas declined to comment further.

Thomas said Love Life was a mid-priced brand that would complement the staple goods offered by Essential Waitrose as well as the more indulgent treats available under upmarket banners such as Duchy Originals and the Heston range. The new boss of market leader Tesco recently announced plans to launch new brands – although they will not carry the Tesco name – as a way of grabbing customers' attention, and Waitrose's move will put pressure on rival Marks & Spencer which is also targeting healthy eating.

The Essentials brand helped Waitrose to shake off its reputation for being more expensive than rivals, and it upped the ante last year with a long-term promise to match Tesco prices on 1,000 branded products including everyday items such as Heinz baked beans and Fairy Liquid.

It has continued to enjoy strong growth despite tough conditions in the wider market as food and fuel price inflation eats into consumers' spending power.

Part of the employee-owned John Lewis Partnership, it is expanding aggressively with plans to open 40 stores this year, including the new convenience format Little Waitrose. The warm spring has also helped, with sales up 7.3% last week.