Diet guru Tim Spector reveals the ‘wholesome’ grocery store bread that’s something however – and the very best sort that is free from chemical compounds linked to cancers

One of the nation’s best known diet experts has warned shoppers not to choose ‘healthy’ sourdough bread when doing their supermarket shop. 

While fresh versions bought from bakeries are full of gut-boosting bacteria, pre-packaged sourdough on supermarket shelves often contain chemicals that have been linked to cancer.

This is according to renowned nutrition scientist Professor Tim Spector, founder of the popular Zoe diet app, who took to Instagram to issue the warning. 

Prof Spector said many supermarket loaves are labelled ‘sourdough’ to ‘fool’ us into thinking they are healthy. 

Some products may also use terms such as ‘high fibre’, he added. However these claims are nothing but a ‘health halo’.

In fact, these breads contain ‘several chemicals to including commercial yeasts, flavourings and emulsifiers to imitate the taste of real sourdough in far less time’. 

Emulsifiers, used to add bulk to food, are found in a range of popular products — from cakes to children’s yoghurts. 

However, experts have suggested that emulsifiers can ‘mess up’ the separation between the fatty layer and water layer in the gut, leading to gaps in the protective gut lining. 

This is thought to increase the risk of bacterial infections in the gut, some of which are known to trigger the development of bowel cancers.  

Microbiome expert Dr Alasdair Scott recently told The Mail on Sunday: ‘We think that this process could be linked to bowel cancer.

‘Studies done on animals that confirm this, but not yet on people — in humans it can be much more difficult to prove why exactly a tumour has formed.’

A healthier bread choice, Prof Spector told his 665,000 Instagram followers, would be freshly baked sourdough, rye or spelt loaf, bought from a bakery. 

‘When I am at home and I have time, I like to make my own sourdough generally rye with lots of seeds in it,’ Professor Spector said. 

‘If I’m having to go out and get some other bread you’re looking at the fibre to sugar ratio. 

‘I’d be going for really high amount of fibre, low amount of sugar and if possible be looking for sourdough bread.

‘You’re better off actually going to a baker. I like to pick ones made from rye or spelt flour because they are much higher in fibre.’ 

Prof Spector said supermarket versions of sourdough can contain chemicals that interfere with the gut microbiome. However, other experts say ‘sprouted’ breads are bowel-friendly due to the added fibre they contain

Adequate fibre intake is essential for protecting against a range of digestive diseases, including bowel cancer. 

Health experts recommend we eat around 30g of fibre per day — found in wholegrains, fruits, vegetables, seeds and pulses — however the average Brit only takes in about 18g. 

Professor Spector added that traditional sourdough could even help symptoms of irritable bowel syndrome (IBS) in comparison to industrially produced bread.

That’s because the methods used to make sourdough break down some of the gluten in the flour, making it easier to digest and causing less problems lower down your gut. 

Research has also shown that compared to wholewheat bread, rye, a type of sourdough, appears to keep you fuller for longer. 

Last year, one dietician told MailOnline that shoppers ought to look out for the word ‘sprouted’ when buying their bread .

Sprouted bread is a type of bread made from ground-up whole grains of the wheat plant that have been left in a moist environment to germinate until they sprout.

This process makes the whole grain bread even more nutritious, as germinating the grain increases the body’s ability to absorb the nutrients.

It means that sprouted wheat is slightly higher in some vitamins and minerals than other whole wheat breads.

Sprouted wheat bread is also sometimes described as a wholegrain bread, as can any bread made from grains like barley, oats, spelt and wheat.

White bread, however, is made from wheat flour that undergoes a milling process to remove most of the plant kernel, doing away with most of the vital nutrients like fibre and B vitamins.