Gut health is a hot topic in nutrition right now, but most clients still confuse two of the most important terms: prebiotics and probiotics. These words are often used interchangeably, even though they refer to two very different things with very different roles.
As a coach or nutrition professional, it’s essential to help clients understand how prebiotics and probiotics work together to support digestion, immune function, and overall wellbeing.
This article will break down exactly what each does, where to find them in food and supplements, and how to guide your clients in using them effectively.
What Are Prebiotics?
Prebiotics are non-digestible fibres that act as food for the beneficial bacteria living in our gut. The human body lacks the enzymes to break these fibres down, but the bacteria in the colon can ferment them, producing compounds that support health.
Think of prebiotics as the fuel source that keeps the “good” bacteria thriving. Without enough prebiotics in the diet, the gut microbiome becomes less diverse and may function less effectively.
Not all fibre is prebiotic. For a fibre to qualify as a prebiotic, it must be fermentable. Two of the most well-known and beneficial types are:
Resistant starches (e.g. from bananas, cooked and cooled potatoes)
Fructans (inulin) found in foods like onions, garlic, and leeks
When gut bacteria ferment these fibres, they produce short-chain fatty acids (SCFAs) such as:
Butyrate
Acetate
Propionate
These SCFAs are incredibly important because they:
Help prevent harmful bacterial overgrowth
Strengthen the gut barrier by thickening the mucosal layer
Fuel colon cells, supporting gut integrity
Potentially reduce inflammation throughout the body
Encouraging clients to get a variety of fermentable fibres can help promote a balanced, thriving microbiome and better overall digestive health.
Prebiotic-Rich Foods and Supplements
The good news is that prebiotics are easy to add to your clients’ diets through everyday plant-based foods.
The more fibre diversity, the better the range of bacterial strains supported in the gut.
Common dietary sources of prebiotic fibres include:
Asparagus
Bananas (especially slightly green)
Onions and garlic
Leeks
Jerusalem artichokes
Oats
Legumes (lentils, chickpeas, beans)
Beetroot
Pineapple
Each of these foods contains fibres like resistant starch, inulin, and oligosaccharides, which survive digestion and reach the colon where they ferment.
What about supplements?
For clients who struggle to get enough prebiotics through diet alone, supplemental forms of inulin, FOS (fructo-oligosaccharides), or resistant starch are available. However, it’s always best to take a food-first approach, using supplements only when necessary and under professional guidance.
A key coaching point: advise clients to slowly increase fibre intake to prevent digestive discomfort and gas, which can occur if fibre is added too quickly.
What Are Probiotics?
Probiotics are live microorganisms—mainly bacteria and yeast—that can provide health benefits when consumed in adequate amounts.
Unlike prebiotics, which feed existing bacteria, probiotics are thought to directly add to or support the bacterial community in the gut.
The most well-researched probiotic strains include:
Lactobacillus species
Bifidobacterium species
Saccharomyces boulardii (a beneficial yeast)
Streptococci species
Probiotic bacteria are naturally found in certain fermented foods and are also widely available in supplement form. While their primary role is digestive support, they may also help with nutrient absorption, immune function, and even mood regulation via the gut-brain axis.
Do probiotics permanently change the gut microbiome?
This is still under debate.
Current research suggests that while most supplemented probiotics don’t permanently colonise the gut, they may still exert positive effects while passing through the digestive system. These effects can include reducing gas and bloating, improving lactose tolerance, and temporarily boosting beneficial bacteria counts.
The key message for clients: probiotics complement but do not replace a healthy, fibre-rich diet that nourishes the body’s natural microbiome.
Probiotic-Rich Foods and Supplements
Probiotics occur naturally in a variety of traditional fermented foods. Recommending these foods is often the easiest way for clients to add beneficial bacteria to their diets.
Common probiotic-rich foods include:
Yoghurt (with live and active cultures)
Kefir (fermented milk drink)
Kombucha (fermented tea)
Kimchi and sauerkraut (fermented vegetables)
Tempeh (fermented soy)
Miso (fermented soybean paste)
Actimel, Yakult and other probiotic drinks
These foods offer a variety of probiotic strains and can be an enjoyable, accessible way for clients to support digestive health.
What about probiotic supplements?
Probiotic supplements are popular, especially for clients with specific digestive concerns. They come in capsule, tablet, or powder form and often contain well-documented strains like Lactobacillus rhamnosus GG or Bifidobacterium animalis.
However, the research on their long-term effectiveness remains mixed.
Some people experience noticeable improvements in symptoms like bloating or irregular bowel movements; others see little change.
Your coaching advice:
Recommend food sources first
Use supplements selectively and under guidance
Remind clients that probiotics should complement—not replace—an overall healthy diet and lifestyle
