Prebiotics and FODMAPs can be a bit of a confusing topic to wrap your head around. Part of this confusion is because prebiotics and FODMAPs are often the same foods. For good gut-health and IBS symptom management, it is important to take both into account.
What are prebiotics?
Prebiotics are basically a type of fibre which we can’t digest. So it remains undigested as it passes through the body. When it reaches the large intestine it acts as a food for probiotics, and promotes the growth/activity of good bacteria. This means prebiotics play an important role in gut health, so they’re good guys. The down side to a low FODMAP diet is that is often limits the intake of prebiotics.
Why can a low FODMAP diet be low in prebiotics?
Certain FODMAPs act like prebiotics, and produce similar effects (i.e. help promote good bacteria). The types of FODMAPs which hold prebiotic effects are mainly fructans, galacto-oligosaccharides (GOS), and inulin. Foods high in fructans include wheat products, rye products, onion and garlic. Foods high in GOS include legumes, such as chickpeas and baked beans. Inulin is found in some yoghurts (even some lactose-free), asparagus, garlic/onion, and some confectionary. The reason fructans and GOS are able to act like prebiotics is because we don’t have enzymes to break them down, so they remain undigested like prebiotics.
High FODMAP, high prebiotic foods to initially avoid
The following are foods which are both high FODMAP, and naturally high in prebiotics. These should be avoided initially during the elimination phase of a low FODMAP diet, and reintroduced during the challenge phases.
- Wheat/rye breads, couscous, wheat pasta, barley and gnocchi
- Jerusalem artichokes, garlic, onion, leek, asparagus, beetroot, peas, snow peas, and sweet corn.
- Nectarines, peaches, watermelon, persimmons, rambutan, grapefruit, pomegranate, dried fruit, custard apples.
- Cashews and pistachios
- Foods containing inulin – read ingredients lists carefully.
Some low FODMAP, prebiotic-containing foods
The following are foods which are low in FODMAP per serve, and naturally contain prebiotics. These can be included during the elimination phase.
- Chicory leaves (<1 cup), fennel bulb ( ½ cup), green section of leeks and spring onion, beetroot (2 slices or 20g), sweet corn ( ½ cob), canned lentils ( ½ cup), red cabbage (1 cup)
- Banana, rhubarb, kiwifruit, rambutan (2), dried cranberries (1 tablespoon), pomengranate ( ½ small or ¼ cup seeds).
- Oats (providing not coeliac)
The importance of not restricting FODMAPs long-term
One of the reasons a strict low FODMAP diet is not recommended long-term is because of the restriction of prebiotic foods fructans, GOS, and inulin. Cutting out all of these foods long-term means a likely low prebiotic intake long-term. This could lead to negative impacts on gut health, by reducing the levels of good gut bacteria. Long-term restriction could also result in an overall low fibre intake, including prebiotic fibre. Fibre is important in healthy bowel function, gut health and weight management.
Monash University. Dietary Fibre and natural prebiotics for gut health: FAQs. Monash University. Available from: http://www.med.monash.edu.au/cecs/gastro/prebiotic/faq/#6
Lennard L.B. New and Emerging Developments in Food Production. In: Wahlqvist, M.L, editor. Food and Nutrition: Food and Health Systems in Australia and New Zealand. 3rd ed. Crows Nest: Allen and Unwin, 2011; 183-189.