The human digestive tract, starting with the stomach and leading up to the intestines, is celebrated every year on May 29, on the occasion of World Digestive Health Day (WDHD). We also celebrate the denizens of the human gut, the different types of bacterial colonies that live and thrive within the human digestive system, and their impact on digestion. Beyond digestion, the human gut bacteria (especially the beneficial ones) also have a symbiotic relationship with the human immune system and help prevent many diseases. The WDHD theme for this year was obesity, and a paper published in ‘Nature’ in April 2019, had established a clear role of the bacteria in treating obesity in humans.
If the human gut microbiota is so crucial in keeping humans healthy, it is important that we spend some time understanding what keeps the microbiome healthy. Plus there are beneficial bacteria and harmful ones, and it is key that their balance is maintained.
So, what is the food that these good bacteria consume and what do they produce that helps the host humans? In our markets, we have often seen products marked as “probiotic” and “prebiotic”. While probiotics are the beneficial bacteria cultures, which boost their presence in the human gut, the lesser-known term ‘prebiotics’ are the foods that keep the good bacteria going. It is important for us humans to understand prebiotics, to keep our microbial partners in our gut healthy.
What Are Prebiotics?
Prebiotics are essentially dietary fibers that are selectively utilized by host micro-organisms to produce metabolites that the human body is able to use. These non-digestible carbohydrates such as fructo-oligosaccharides and galacto-oligosaccharides cannot be digested by the enzymes produced by the human body. They help in multiple ways, firstly by helping strengthen the digestive tract. Later, the beneficial microbes break down prebiotics into secondary metabolites that are absorbed into the host and provide multiple health benefits such as stimulation of immune cell activity, for instance. Such interventions have shown to improve immune markers in infants, reduce risk of infections among young children and decrease inflammatory processes among the elderly.
Types of prebiotics that help to nourish our gut microbes
Fructan: Inulin and fructo-oligosaccharides (FOS) or oligo fructose is a component of fructan. They are resistant to digestion enzymes such as alpha-amylase, saccharase, and maltase. They increase the growth of Bifidobacterium. Wheat products, barley, onions, shallots, garlic, cabbage, broccoli, pistachio, artichoke, chicory root, and asparagus are high in them.
Galacto-oligosaccharides (GOS): GOS is found naturally in mammalian milk. GOS is generated industrially from whey, which is gaining traction as a possible alternative. Bifidobacteria and Lactobacilli are greatly stimulated by GOSs. Isolated GOS is also used in the production of fruits and dairy products. GOS and FOS mixes are also included in some infant meals.
Xylo-oligosaccharides (XOS): Plant sources of XOS include Bengal gram husk, wheat bran, straw, barley hulls, brewery waste grains, almond shells, bamboo, and maize cob. It can assist people with type 2 diabetes mellitus lower their cholesterol and LDL. XOS also has antioxidant qualities and is utilised in food items as a gelling agent.
Lactulose: Lactulose is a chemically synthesised sugar that is generated from lactose. Lactulose can be found naturally in heat-treated cow and human milk. Daily doses of 3g lactulose can boost the gut microbiota in healthy people. In hospitals, it is commonly used to treat persistent constipation.
Benefits of prebiotics for gut health
Let us now look at the benefits of consuming the right prebiotics. Gut microorganisms are known to control multiple aspects of the mucosal immune system. The effects of prebiotics can be direct, or indirect by increasing the population of beneficial microbes, especially of Lactobacilli and Bifidobacteria. Research has shown that prebiotics may help support immunity, digestive health, and gut comfort, which is particularly important for vulnerable consumer groups such as infants.
Prevents Obesity: Important prebiotics plays a crucial role in preventing obesity and ensuring the gut microbiota plays their right role. Firstly it strengthens the gut barrier, prevents the formation of low-grade inflammations, and hence improving metabolic changes that aid weight reduction. Secondly, prebiotics also is seen to increase the secretion of peptides like glucagon the promote satiety or a sense of fullness, and at the same time, they help reduce the synthesis of ghrelin, another peptide that increases the feeling of hunger.
Boosts immunity: Given that the gut contains 70% of our immune system cells, Galacto-oligosaccharides (GOS), a prebiotic generated from lactose in milk, are not digested in the upper section of the gastrointestinal tract and reach the large intestine where they help the development of beneficial bacteria Bifidobacterium. These bacteria have the ability to create short-chain fatty acids and other metabolites that boost immunological functions and enhance digestive health.
Keeps harmful bacteria in check: Because the beneficial Bifidobacterium compete for food sources and attachment sites on the intestinal mucosa, an increase in beneficial bacteria boosted by the presence of suitable prebiotics can also help reduce the number of dangerous bacteria.
There is also a key role for prebiotic food additives in sugar-free foods. Prebiotics are sweet in taste and help mask any bad after-taste of foods, and combine very well with artificial sweeteners to make sugar-free foods tasty. The worldwide prebiotic ingredients market is expected to grow at a considerable CAGR of 10.5% over the next few years. The Covid-19 pandemic has brought the spotlight back on building immunity, health, and wellness. With approximately 37 million diabetics and 400 million overweight people in India, there is an increasing demand for low-sugar foods, which will also increase demand for prebiotic additives in food. 5
Clearly, prebiotics has a dual benefit. While it helps promote digestive health and healthy gut microbiota, it also makes sugar free food tastier. As Indians become more and more aware of the benefits of prebiotics, we will see foods with added prebiotics will find wider acceptance among the health-conscious Indian consumers.
(The author is chief operating officer - Nutrition Sciences at Tata Chemicals.)