Nutrition briefing
Fructooligosaccharides (FOS)
FOS is a type of carbohydrate made of short fructose chains, found naturally in many plants including bananas, watermelon, onions and artichoke. It is a prebiotic: it feeds the beneficial bacteria in your gut, which can lead to improved digestion and increased nutrient absorption, among other benefits.
What FOS does
Fructooligosaccharides are short chains of fructose that your own digestion cannot break down. Instead, they travel through to the large intestine where your beneficial gut bacteria ferment them. That feeding effect is what makes FOS a prebiotic.
Found naturally in plants
FOS occurs in many everyday foods, including bananas, watermelon, onions and artichoke. You can lift your intake simply by choosing more of the vegetables, fruit, grains, pulses and seeds listed below.
Feeds your good bacteria
By feeding the beneficial bacteria in your gut, FOS can promote a healthy gut microbiome and support improved digestion, increased nutrient absorption and overall gastrointestinal health.
FOS-rich foods
Foods are grouped from Very best down to Moderate by how much FOS they provide. Quantities are a guide: ½ cup and raw unless otherwise stated for vegetables, 1 cup unless otherwise stated for fruit, and ½ cup unless otherwise stated for grains, pulses and seeds.
| Tier | Vegetables | Fruit | Grains, pulses + seeds |
|---|---|---|---|
| Very best | Jerusalem artichoke | ||
| Best | Broccoli stalks Red onion (¼ cup) |
Longan Watermelon |
|
| Good | Asparagus Brussels sprouts Red cabbage Fennel bulb Leek Button mushrooms Snow peas White onion (¼ cup) |
Banana (1 large) Red currants |
Red kidney beans, boiled Ryvita (3 biscuits) Sunflower seeds (2 tbsp) |
| Moderate | Beetroot Globe artichoke Okra Savoy cabbage Scallion / spring onion (1 stalk) Shallot (1 bulb) |
Red plums (2 medium) | Butter beans, canned Gluten free muesli Wheat bran cereal (85%) Wheat bran, raw (1 tbsp) |
Please note: FOS content may vary depending on factors such as growing conditions, ripeness and processing methods.
Everyday tips
Use onions, leek and garlic freely
They can be added to almost any savoury dish to boost its prebiotic content.
Roast Jerusalem artichokes
Roast them with a little lemon, thyme and honey for a delicious addition to main meals.
Snack on FOS-rich fruit
Bananas, watermelon and red plums make a snack that is both healthy and delicious.
Keep the broccoli stalks
When chopping up your broccoli, keep the stalks on for a FOS boost.
Add beans to soups and salads
Incorporate red kidney and butter beans into your soups and salads. Red kidney beans make a great meat alternative in Mexican nachos or chilli recipes.
In some people, FOS may cause digestive upset such as bloating and gas. If you are sensitive, increase FOS-rich foods gradually and notice how your gut responds.
Jerusalem artichoke vs globe artichoke
These two foods share a name but are very different plants, and they sit in different tiers above.
Jerusalem artichoke Very best
Produces edible tubers with a sweet, nutty flavour. It is the single richest FOS food on the list.
Globe artichoke Moderate
Produces edible flower buds with a mild, slightly bitter taste.
Recipe ideas
Watermelon slushie (serves 4)
Ingredients
- 8 cups frozen watermelon cubes
- Juice of 1 large lime
- ¼ cup mint
- 3 tbsp maple syrup
- 1.5 cup filtered water
Method
- Add the ingredients to a blender.
- If the mixture is too thick, add extra water.
- Serve in your favourite glasses.
Nut butter Ryvita (serves 4)
Ingredients
- 8 Ryvita crackers
- 4 tbsp sunflower seed butter (or nut butter of your choice)
- 2 bananas, sliced
- 4 tbsp honey
Method
- Divide the Ryvita crackers evenly across 4 plates.
- On each cracker, spread ½ tbsp of nut butter, top with sliced banana, and drizzle with ½ tbsp honey.
Broccoli and apple salad (serves 4 as a side dish)
Ingredients
- 1 green apple, finely chopped
- 1 medium head of broccoli, finely chopped (including stems)
- ½ cup flaked almonds
- 1 medium red onion, diced
Dressing
- 2 tbsp Dijon mustard
- 2 tbsp extra virgin olive oil
- 1 tbsp honey
- 2 tbsp fresh lemon juice or apple cider vinegar
- ¼ tsp salt
- ½ tsp pepper
Method
- Whisk all the dressing ingredients in a jar or jug.
- In a separate bowl, add the apple, broccoli, almonds and red onion. Stir to combine.
- Add the dressing to the bowl and stir to combine.
Frequently asked questions
What is FOS and why is it good for gut health?
FOS, or fructooligosaccharides, are short chains of fructose found naturally in foods like bananas, onions and artichokes, and they act as a prebiotic. Because the small intestine cannot digest FOS, it passes through to the large bowel where beneficial bacteria ferment it as fuel. That fermentation is what makes FOS a prebiotic, supporting a healthier gut microbiome, better digestion, improved nutrient absorption and overall gastrointestinal health.
What foods are highest in FOS?
Jerusalem artichoke tops the list as the richest everyday source of FOS. Other strong sources include broccoli stalks and red onion, followed by asparagus, Brussels sprouts, red cabbage, fennel bulb, leek, button mushrooms, snow peas and white onion, with banana and red currants also contributing. Simple ways to include them are roasting Jerusalem artichokes, using onions, leek and garlic in savoury dishes, and keeping broccoli stalks rather than discarding them.
Can FOS cause bloating or gas?
In some people FOS can cause digestive upset such as bloating and gas, because it is fermented by gut bacteria in the large bowel. If you are sensitive, the suggested approach is to increase FOS-rich foods gradually and notice how your gut responds, rather than adding a large amount at once. For most people this lets the microbiome adjust so the prebiotic benefits can be enjoyed comfortably.
Reviewed by Rohan Smith, BHSc Nutritional Medicine · Elemental Health & Nutrition, Adelaide. Last reviewed 13 June 2026.
Important: This summary is general information, not personalised medical advice, diagnosis, or a treatment protocol. Speak with a qualified practitioner about your individual situation. Book a consultation →