Maintaining a
healthy balance of good and bad bacteria in your gut?
The
human gut is home to trillions of bacteria. These bacteria are found in low
numbers in the stomach and small intestine, with the majority residing in the
large intestine. The gut naturally contains both harmful (pathogenic) and
beneficial bacteria, and in a healthy gut there is a balance between these
types of bacteria. Maintaining a healthy balance of bacteria is important for
normal gut function, enabling the fermentation
of fiber and carbohydrates, maintaining stool regularity, protecting against pathogenic bacteria,
ensuring normal immune system development and facilitating nutrient metabolism. Factors that influence
this balance of ‘good’ and ‘bad’ bacteria include age, medications, infection, the
immune system and diet and possibly pre- and probiotic consumption. Because certain
types of beneficial bacteria (eg. bifidobacteria)
feed on prebiotic fibres, one way of increasing the number of good bacteria in
the gut is by eating prebiotic carbohydrates. Microbial population in the gut might
also be influenced by probiotic supplement consumption.
Monash Research into a high prebiotic diet
The Department of Gastroenterology at Monash University is researching
the impact of a 'high fibre and high natural prebiotic diet'. This diet is
designed to establish a healthy balance of gut bacteria, needed for optimal
health. While the diet is essentially a high fibre diet, it emphasises the
consumption of foods that are high in 'prebiotic' fibres.
What is a
prebiotic?
A prebiotic is a
type of fibre, thus while all prebiotics are fibre, not all fibre is prebiotic.
To be classified as a
prebiotic, the fibre must pass through the GI tract undigested; undergo
fermentation by beneficial bacteria and selectively stimulate the growth and/or
activity of certain strains of beneficial bacteria in the large intestine
What foods are
naturally high in prebiotics?
Carbohydrates
classified as having prebiotic effects include inulin, lactulose,
fructooligosaccharides (fructans / FOS) and galactooligosaccharides (GOS). The
following table outlines food sources of prebiotics:
Vegetables
|
Jerusalem artichokes, chicory,
garlic, onion, leek, shallots, spring onion, asparagus, beetroot, broccoli,
brussels sprouts, butternut pumpkin, savoy cabbage, fennel bulb, green peas,
snow peas, sweetcorn
|
legumes
|
Chickpeas, lentils,
red kidney beans, baked beans, soybeans
|
Fruit
|
Custard apples,
nectarines, white peaches, persimmon, tamarillo, watermelon, rambutan, grapefruit,
pomegranate
|
Bread / cereals /
snacks
|
Barley, rye bread, rye
crackers, wheat bread, pasta, gnocchi, couscous, wheat bran, oats, muesli-based
fruit bars
|
Nuts and seeds
|
Cashews, pistachio
|
Other
|
Human breast milk
|
Legumes are
particularly good sources of prebiotics. The following chart compares the
prebiotic content of different legumes.
What are the
health benefits of eating a diet high in prebiotics?
Because prebiotics are a
relatively new discovery, evidence supporting their health benefit is only
beginning to accumulate. Some health benefits attributed to prebiotic intake
include modulation of the gut microbiota; improved mineral absorption; protection
against colon cancer; improved blood glucose and insulin profiles; protection
against intestinal infections and alterations in the progress of some
inflammatory conditions.
For high prebiotic recipe ideas and a meal plan, check out
the Monash University High Natural Prebiotic Diet webpage: http://www.med.monash.edu/cecs/gastro/prebiotic/
