• Shirley Yeung

Gut Health - The Role of Microbiomes, Probiotics and Prebiotics

Shirley Yeung, HK BioTek Nutritionist





The human body is a host of 100 trillion bacteria and other microbes, collectively known as microbiomes. It has been estimated that the human gut microbiota contains more than 1000 different species of known bacteria. Good bacteria are incredibly important for our health as they assist digestion and absorption of nutrients. When the balance between good and bad bacteria is disturbed, people have a higher risk of developing systemic diseases such as obesity and diabetes. Also, there is a growing number of researches showing that gut microbiome, gut health, and food sensitivity are closely connected.

Unique gut microbiota

A baby is exposed to the bacteria of its mother when micro-organisms from the mother colonizes the newborn’s digestive tract as its gastrointestinal tract begins to develop. There is research showing that bacteria in mother’s breast milk seed the infant gut, which plays an essential role in the development of the infant gut microbiome. The composition of our microbiota evolves throughout our lives and is affected by the environment.

One-third of our gut microbiota is common to most people while two-thirds are unique to each individual. It is now apparent that our gut microbiome co-evolves with us. Gut microbiota is important in maintaining normal body functions. Apart from assisting digestion and absorption, microbiota promotes a wide range of health benefits, including vitamin production, energy production, regulation of lipid metabolism and short chain fatty acid production.

Probiotics - Friendly bacteria to the gut

Probiotics are live microorganisms that promote health benefits, especially to the gut. When consumed in an appropriate amount, they fight and suppress bad bacteria. Lactobacillus and Bifidobacterium are the two most common strains of probiotics which can be found in fermented foods such as yogurt, kefir, sauerkraut, kimchi, and bacterially cultured cheese. Healthcare professionals may recommend probiotics as supplementation to patients on antibiotics, in order to repopulate the colon with desirable bacteria after treatments.

Although probiotic foods and supplements are generally safe for most people, it is always a good idea to consult your doctor or healthcare professional before taking any probiotics supplements. Mild side effects may include diarrhea and bloating on the first few days. Moreover, pay attention to habits that may destruct the gut bacteria. For instance, an overdose of prescription antibiotics, excessive alcohol intake, smoking, and poor sleeping habits are considered as probiotic killers. In addition, probiotic strains are fragile and can easily be destroyed by the stomach acid and heat. Read the instructions carefully whenever taking probiotic supplement.

Prebiotics - Food for probiotics

Although prebiotics and probiotics sound similar, they are actually very different and have different roles in the digestive system. Prebiotics including inulin and fructo-oligosaccharides are non-digestible carbohydrates consumed by good bacteria, including probiotics. They boost the growth of good bacteria.

Dietary fibre is the major source of prebiotics which is naturally presented in the non-digestible part of fruits and vegetables such as banana, apple peels, and bean, etc. Prebiotics can also be taken in the form of nutritional supplement.

Prebiotic fibre travels along the small intestine and is fermented when it reaches the colon. This fermentation process favours good bacteria colonies and helps to increase the number of desirable bacteria in the gut. Prebiotics are not as fragile as probiotic strains as they are not easily affected by heat or stomach acid.


Table 1. Differences between prebiotics and probiotics


Improving your gut health

Apart from probiotics and prebiotics, diet and lifestyle-related factors also have an impact on your gut health. To keep the gut healthy, here are some advices:

  • Increase the overall fibre intake as prebiotics promotes stimulation of peristalsis

  • Opt for probiotic-rich whole foods first instead of consuming probiotics as supplements

  • Drink enough water every day and reduce alcohol intake

  • Reduce the amount of junk food and switch to healthier alternatives, such as dried fruits and nuts. Your gut does not like processed foods, even if you do.


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