Ten prebiotic foods you need to know about
Gut health has become a hot topic in the world of nutrition and as research evolves it’s becoming very clear that the beneficial role of microbes found in the gut goes way beyond digestion. The collection of microbes in your gut are referred to as your microbiome and advice about how to protect it has become commonplace.
Your gut microbiome is sensitive to your lifestyle and dietary habits; both can either promote a good diversity of microbes in the gut or tip the balance in the opposite direction, which may have a negative impact on your health.
The foods that can have the biggest positive effect on your microbiome are those containing beneficial bacteria (probiotics) and those containing indigestible fibres referred to as prebiotics.
Your microbiome is unique like a fingerprint
The term ‘microbiome’ refers to the collection of microbes that live in and on the body, of which there are around 100 trillion, the majority of which are found in the gut. These bugs form a protective barrier defending the body from foreign invaders, which can be harmful to health.
The microbes in your gut include bacteria, which are essential for efficient digestion. These bacteria also help to digest antioxidant polyphenols, synthesise vitamins such as B12, D, folic acid and thiamine, and produce short chain fatty acids that provide energy to the cells of your colon helping to maintain a strong gut barrier. Gut bacteria have also been shown to play a role in immunity and new research is starting to explore the effect on the brain with early findings linking the diversity of bacteria in your gut to mental health and obesity (via the effect on hormones that control appetite).
Like a fingerprint, your microbiome is unique, and its composition is dictated by the world around you and within you.
Cultivation is key to a healthy microbiome
It’s yet unclear what constitutes a ‘healthy’ microbiome but one thing for sure is that it takes a bit of cultivation. If your gut becomes overrun with bad bacteria then this can upset the balance of your microbiome, which may lead to symptoms such as bloating, excessive gas, abnormal bowels, bad breath and fatigue.
A poor diet is characterised by an over-consumption of sugar and bad fats, whilst lacking in nutritious foods such as vegetables and other wholefoods including beans, pulses and wholegrains. This type of diet has been shown to promote the overgrowth of bad bacteria in the gut (1, 2, 3).
Medication can also impact on gut bacteria as the overuse of non-steroidal anti-inflammatory drugs (NSAIDS) and antibiotics have the potential to destroy them, which can leave your gut vulnerable and increase the risk of infection.
What are prebiotics?
No doubt you will have heard about probiotics, which are friendly bacteria found in foods such as live yoghurt and supplements. Other foods such as kimchi, kefir and miso also contain bacteria, which are beneficial to health.
The role of prebiotics is less well understood but they’re equally, if not more important than probiotics as these indigestible fibres help the bacteria in your gut to thrive. Probiotic supplements have the potential to be very beneficial, especially if you need to re-balance the diversity of bacteria in your gut but the same is not necessarily true of prebiotics.
There are many food sources of prebiotics, which include inulin, lignin, oligosaccharides, mucilage gums, non-starch polysaccharides (pectin and beta glucans) and resistant starches. Foods containing these prebiotics can easily be incorporated into your daily diet and many of which you may already be eating on a regular basis. You’re more likely to be eating prebiotic foods if your diet is healthy and contains plenty of plant-based foods.
Ten top prebiotic foods to include in your diet
There are quite a few prebiotic foods, but I have chosen the ones that are more commonly eaten and easily accessed from your local supermarket.
This vegetable is now available in larger supermarkets and is in season between October and February. Jerusalem artichokes contain 2g of fibre per 100g and 76% comes from inulin. You can also glean a good source of thiamine (healthy nervous system and releases energy from food) and iron (healthy immune system, red blood cell production and wards of tiredness) from Jerusalem artichokes.
These are not a commonly eaten vegetable as many people are unsure how to use them. Jerusalem artichokes have a nutty flavour and can be used in the same way as potatoes in that they can be roasted and mashed, and also work well in soups.
This vegetable is closely related to onions and leeks. Garlic can form the base of many home-cooked dishes alongside onions, which means it’s easy to add to your daily diet. Around 11% of the fibre found in garlic comes from inulin and 6% from fructooligosaccharides, which add a slight sweetness to its flavour.
Onions are another food that can easily be included into your daily diet as it acts as a base for many home-cooked dishes. Around 10% of the fibre found in onions comes from inulin and 6% from fructooligosaccharides. Onions also contain a good source of vitamin C (protects cells, maintains healthy skin and helps with wound healing) and the flavonoid quercetin, which acts as an antioxidant in the body.
This vegetable is similar to garlic and onions but less commonly used. Around 16% of the fibre found in leeks is from inulin. Leeks are also high in flavonoids, which support the body to respond to oxidative stress. You can also glean a good source of vitamin A (healthy immune system, eyes, skin and mucosal linings such as the nose), vitamin C (protects cells, maintains healthy skin and helps with wound healing) and vitamin K (blood clotting and healthy bones) from leeks.
You can serve leeks as a side dish, incorporate into soups or a topping for pies.
There’s a lot of truth in the saying about an apple a day keeping the doctor away, and this includes the health of your gut. Around 50% of the fibre found in apples is from pectin. This prebiotic not only benefits the health of your microbiota but has been shown to help reduce cholesterol. Apples are also high in polyphenol antioxidants.
As well as snacking on apples you can use them to make fruit puddings, add to savoury dishes and grate as a topping for yoghurt or soaked oats.
This vegetable is now available all year round with supermarkets importing it from countries such as Peru. To savour the best tasting Asparagus and save on food miles, you’re better to wait until the British asparagus season, which occurs between April and May. Asparagus is not as rich in prebiotics as other vegetables with only around 5% of the fibre coming from inulin. This vegetable also contains a good source of vitamin A (healthy immune system, eyes, skin and mucosal linings such as the nose), vitamin K (blood clotting and healthy bones) and folate (healthy red blood cells and protection against neural tube defects in unborn babies).
Asparagus is delicious served on its own with a big drizzle of olive oil or topped with a poached egg for breakfast. You can also add asparagus to pasta dishes, risottos and soups.
These fruits are one of the most commonly eaten in the UK and contain small amounts of inulin. Unripe (green) bananas are high in resistant starch and feature as an ingredient in many Caribbean dishes. Bananas are also a good source of vitamin B6 (converts food into energy and helps to form haemoglobin in red blood cells).
Bananas can be eaten as a snack, baked and used in smoothies and fruit puddings. For something different, try adding to curries.
This grain is not as commonly used as others such as rice but is actually hugely versatile once you know how to use it. Barley contains around 8g of beta glucan per 100g, which is not only good for your gut but has been shown to help reduce cholesterol. Barley also contains the minerals magnesium (converts food into energy, promotes muscle relaxation and healthy bones) and selenium (protects cells and promotes a healthy immune system).
Barley can be used in place of rice to make risotto, added to soups or salads (cooked).
Potatoes are a starchy carbohydrate as are other foods such as grains. Starches are long chains of glucose, which the body uses for energy. When potatoes are cooked and then cooled, they develop resistant starches, which the body is unable to break down and as such behave as prebiotics.
These seeds are hugely healthy and a good source of prebiotics with 20-40% of their fibre coming from mucilage gums and 60-80% from cellulose and lignin. Flaxseeds also contain phenolic antioxidants and are a useful source of protein. You can also glean a good source of minerals from flaxseed including magnesium (converts food into energy, promotes muscle relaxation and healthy bones), iron (healthy immune system, red blood cell production and wards of tiredness), calcium (healthy bones and teeth) and zinc (converts food into energy, involved in making new cells and enzymes and helps with wound healing). Flaxseed are also rich in omega 3 and although the conversion to more usable forms of this fatty acid in the body is poor, it’s still a useful source, especially for people following a plant-based diet.
You can add seeds to any dish and also smoothies.
If you’re eating a healthy diet, then many of the foods included will naturally take care of your gut and including the foods listed above will be especially useful to promote the health of your microbiome.