Tuesday, March 31, 2015

High Prebiotic Diet Including Legumes

By Dr Jane Varney and Dr Jane Muir, Monash University

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/