Foods to avoid to keep a healthy gut.

Artificial Sweeteners

    Sure, they have been passed by the FDA as being safe food additives, however, recent research has shown they influence the composition and function of our gut microbes in a negative way.  They actually promote metabolic disease (the very problem they were introduced to combat!).

Food Emulsifiers

    Food emulsifiers are used in foods such as salad dressings to promote the mixing of oil and water products.  Heaven forbid we have oil and vinegar separate!  Two ingredients to watch out for are carboxymethylcellulose and polysorbate-80.  They act like detergents in the gut, which disturbs the mucosal layer and promotes a pro-inflammatory, obesity type phenotype in the gut.  

Artificial Food Colours

    Azo dyes in particular have the most potential for harm in humans.  The FDA has considered them safe because they are “stable” but our microbes can easily metabolize them, creating very harmful metabolites, which can create hyperactivity in children.



    Foods to eat to promote a healthy gut.


  • Fermentable carbohydrates - cereals, fruits, vegetables.  The three most important types of carbohydrate prebiotics are these short-chain nondigestible carbohydrates:
    • Inulin-type fructans - Primarily found in vegetables and particularly chicory root.  This type of fibre causes significant changes to the composition of the gut microflora with increased number of beneficial bacteria and reduced number of potentially harmful species.  
    • Fructo-oligosaccharides - such as the fibre found in onion, chicory, garlic, asparagus, banana, artichoke and many others.
    • Galacto-oligosaccharides - important for infants drinking human milk.

     These carbohydrates are fermented to organic acids, which provide energy for other bacteria, the bowel epithelium (tissue lining the bowel) and peripheral tissues.  With an appropriate ample food source, the beneficial bacteria of the gut can proliferate and outnumber the opportunistic bacteria.  There will always be opportunistic pathogens in your gut, such as E. Coli and C. Difficile, for example, however, it is all about the homeostasis of a diversity of microbes.  If you properly feed beneficial bacteria and they flourish, there will be fewer opportunistic pathogens.  We don’t however, want to abolish the potentially harmful bacteria, because, while there is still a lot to be discovered, we know the interactions between all types of microbes in the gut is important.  It is a very complex ecosystem, and every component is important.  

    The major endpoint of carbohydrate fermentation are short chain fatty acids (SCFA).  These are weak acids, which help decrease pH, inhibiting growth and activity of pathogenic bacteria; another benefit of consuming fermentable fibres.  Butyrate is a key SCFA, as it is the principal source of energy for our colon cells.  It is instrumental in maintaining mucosal integrity, as well as modulating inflammation and promoting gene stability.  Another benefit of having plenty of butyrate is it helps protect against cancer as it regulates colon cell function and promotes the removal of dysfunctional cells.

Protein - Animal protein, nuts and seeds, legumes

    Nitrogen is very important for microbial growth and dietary protein is a major source of it.  Plenty of nitrogen enables microbes to up their production of SCFA.  Protein also produces greater diversity, gases and metabolites, which are beneficial for our microbes.


    The benefits of probiotics typically only last for as long as they are taken, however, they still can have benefits.  Probiotics are dietary substrates that selectively promote proliferation and/or activity of beneficial bacteria indigenous to the colon. Probiotics can help improve immune function by reinforcing the mucosal barrier function, reducing the movement of organisms and metabolites absorbed by the colon, increasing mucosal antibody production, strengthening the lining of the colon and directly blocking pathogens.  However, in human studies, the results of probiotics vary because everyone’s biology and response to probiotics is different, as it depends on age and health state, so it is challenging to study.  Nonetheless, it doesn’t hurt to consume them, as any benefit is good.