We are quite familiar with probiotics. Benefits of probiotics, particularly in maintaining an optimal gut health, have made the concept of fermented food like kimchi, miso, kefir, sauerkraut and yogurt very popular among the health conscious. Probiotics indeed come with an impressive list of health benefits that go beyond intestinal health.
But what is a prebiotic? Is it another food fad or something real, and with scientific backing?
Prebiotics: Fuel for probiotics
Probiotics introduce healthy bacteria into the gut. On the other hand, prebiotics act as a nourishment for these bacteria as well as the bacteria already present in the gut. Essentially, prebiotic foods serve as a fuel source for the beneficial bacteria. Unlike probiotics, prebiotics can’t be destroyed by heat or stomach acid.
Prebiotics are specialized plant fibres. So basically they are carbohydrates we can’t break down into nutrients in the small intestine. To understand prebiotics better, let’s sum up their attributes:
- Not digested by small intestine
- Reaches the colon where it is fermented by anaerobic gut microflora (particularly Bifidobacterium and Lactobacillus)
- Acts as a food source for probiotics
- Provides nourishment to the good bacteria already existing in the colon
- Does not promote the growth of bad bacteria or other pathogens
A variety of bacteria feed on prebiotics. However, two bacterial groups Bifidobacterium and Lactobacillus, seem to thrive on these non-digestible ingredients. When the bacteria in the colon metabolize oligosaccharides from the food, it leads to the formation of lactic acid and several short-chain fatty acids. Butyric acid or butyrate is one of the many fatty acids that are produced during the fermentation of prebiotics in the gut. Butyrate has been known for its multi-protective effect on the intestinal health .
Bifidobacterium and Lactobacillus are important and dominant part of the overall gut microbiota and have been in the spotlight for their health promoting properties. These friendly bacteria help to:
- Produce certain vitamins
- Produce natural antibacterial and antimicrobial substances.
- Restore good, friendly bacteria lost through the use of antibiotics, through the onset of diarrhea, intestinal infections, chemotherapy and other health conditions.
- Exert strong inhibitory effects against the pathogenic (bad) bacteria in the gut – preventing ‘traveller’s diarrhea’, diarrhea in infants and children
- Control symptoms of ulcerative colitis
- Limit the growth of yeast and mould.
Prebiotics are found naturally in our diet, for example in foods like garlic, onion, asparagus, artichokes, bananas, leeks and whole-wheat foods. Breast milk also contains prebiotics and that is one of the reasons why breastfed babies are known to experience fewer infections in early as well as in later years of life. “The effect of breast-feeding on the intestinal microbiota cannot be attributed to a single compound, but there is accumulating evidence that human milk oligosaccharides play a crucial role.” 
Gut Micro-organisms and Human Health
The human gut is home to a complex microbial ecosystem – consisting of over 1,000 different species of bacteria. These tens of trillions of micro-organisms, a mix of good and bad, are known to play an important role in our digestive health. However, emerging studies are providing solid evidence that the bacteria residing in our gut have a wider role to play in maintaining overall health .
The intestinal landscape maintains a delicate equilibrium between the population of good and bad bacteria, and sets the stage for our overall health status. Any imbalance in the gut microbiota (composition of the gut microorganisms) is called dysbiosis, where the balance tilts favorably towards the growth of unhealthy bacteria. Overuse of antibiotics, poor eating habits, the age factor and emotional stress are all contributing factors in disrupting this delicate balance.
There is a considerable scientific proof that dysbiosis can:
- Cause malabsorption of nutrients
- Impair the body’s immunity
- Disturb the integrity of intestinal mucosa
- Lead to the pathogenesis of many chronic ailments, intestinal ailments including inflammatory bowel disease, leaky gut and colon cancer.
- Lead to the onset of metabolic disorders
- Promote fungal growth in the body
- Cause unhealthy cholesterol levels to rise
- Increase the risk of cardiovascular disease
- Trigger autoimmune and inflammatory disorders
Health Benefits of Prebiotics
- Nourishes the growth of good bacteria, increases the effects of probiotics
- Improves digestion
- Improves bowel regularity
- Boosts immunity
- Increases absorption of calcium and magnesium, improves bone health
- Reduces the incident of antibiotics induced diarrhoea
- Helps in weight loss
- Reduces inflammation and relieves symptoms of inflammatory bowel disease
- Lowers risk of colon cancer
- Reduces LDL cholesterol and triglyceride levels, lowers risk of cardiovascular disease
- Gibson GR, Roberfroid MB Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr. 1995 Jun; 125(6):1401-12.
- Leonel AJ, Alvarez-Leite JI. Butyrate: implications for intestinal function. Current Opinion in Clinical Nutrition and Metabolic Care. 2012 Sep;15(5):474-9. doi: 1097/MCO.0b013e32835665fa.
- Boehm G, Moro G. et al. Structural and functional aspects of prebiotics used in infant nutrition. The Journal of Nutrition. 2008 Sep;138(9):1818S-1828S.
- Jandhyala et al. Role of the normal gut microbiota. World J Gastroenterol. 2015 Aug 7; 21(29): 8787–8803.
- Roberfroid et al. Prebiotic effects: metabolic and health benefits. Br J Nutr. 2010 Aug; 104 Suppl 2():S1-63.