The Health Benefits of Prebiotics

Prebiotics are undigestible nutrients that provide a valuable food source for microorganisms residing in the gastrointestinal (GI) tract. These compounds bypass the acids and enzymes of the digestive system and enter the colon (1). On average, 1010 – 1012 microorganisms per gram live  inside the human colon and these microbes metabolize and ferment prebiotics for their survival (2).


In turn, this promotes the growth and activity of healthy gastrointestinal flora and inhibits the growth of pathogens. Prebiotics are typically found in the following foods (1, 3):

  • Fiber- and Starch-rich foods
  • Fruits (bananas, berries, and apples)
  • Vegetables (peas, onions, leeks, and asparagus) 
  • Legumes. 


Common examples of prebiotics include oligosaccharides, inulin, polydextrose, and lactulose. Key health benefits are associated with the production of short-chain fatty acids (SCFA) which regulates the intestinal barrier, the immune system, and the host inflammatory response. Prebiotics are also beneficial for metabolic health, cancer prevention and can be used to alleviate symptoms of GI disorders.                  


Benefits of Prebiotics

Prebiotics and GI Disorders

Prebiotics can be used to treat or prevent GI disorders, including irritable bowel disease, inflammatory bowel disease, and constipation (4, 5). Dysbiosis of intestinal microbiota refers to an imbalance in the levels of good bacteria. This is a key factor contributing to the development of bowel disorders and constipation. Conversely, prebiotics promote the growth of “good bacteria”, which can help to prevent or treat GI disorders.  



Additionally, the production of SCFA also nourishes the bowel and provides various protective benefits.  A study conducted in 2020 found that inulin helped individuals with irritable bowel syndrome and constipation, due to the improvement  of stool consistency, the transit time of waste passing through the gut, and stool frequency (5). 


Prebiotics and Metabolic Health

Prebiotics can boost metabolic health, as they have been shown to positively affect cholesterol and triglyceride levels, as well as blood sugar levels.  Prebiotics promote the absorption of fats in the lower intestine and bind to cholesterol, reducing low-density lipoprotein (LDL) levels in the blood. This can lower blood pressure as a result


Moreover, studies have shown that inulin-based prebiotics reduced fasting blood sugar levels in individuals with type 2 diabetes and prediabetes, meaning they could potentially be used to prevent metabolic disease(s).    


Prebiotics and Colorectal Cancer

Prebiotics can also reduce the risk of colorectal cancer. This is the third most common type of cancer globally. The production of SCFA can alter gene expression within pre-cancerous cells by canceling out mutations that lead to cancer development. This  provides  anti-cancer benefits.  Additionally, the by-products of prebiotic fermentation can even halt cancer progression by killing cancerous cells. 


Moreover, clinical trials have shown that prebiotics can reduce the levels of certain biomarkers associated with colorectal cancer.   

Pros and Cons of Prebiotics

The prebiotic market is predicted to grow by approximately 15% per year between 2022 and 2030, due to rising concerns amongst the general population about GI disorders. At present, prebiotics are considered a safe option for improving gut health and are not associated with any serious side effects (6). However, large doses between 40 and 50 grams could potentially have adverse  effects like bloating, GI cramps, and flatulence. 


Furthermore, evidence on the benefits of prebiotics for human health is still lacking and more clinical studies are required. Generally, consuming small doses between 2.5 and 10 grams are the best way to reap the health benefits. Alternatively, a diet that is rich in fiber  with a high intake of fruits and vegetables can also help nourish the gut microbiome.  


A healthcare professional can help you decide whether prebiotics are a good addition to your diet based on your lifestyle and health status.  



By: Siobhan Moran M.Sc. Biomedical Science

Copy Edited by: Clare Keeble



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