In which foods are probiotics and prebiotics found?

Microbiota, probiotic, prebiotic… what are we actually talking about?

Our gastrointestinal tracts are populated with approximately 100,000 billion live microorganisms primarily comprising bacteria, fungi and yeasts (1). This vast community is called the intestinal microbiota – previously known as the intestinal flora. It is concentrated mainly in the small intestine and the colon, the stomach’s acidity creating an environment that’s too hostile for its development.

A balanced microbiota, with a diverse range of flora rich in beneficial bacteria, is considered a vector of good health. The microbiota is involved in digestion, metabolism and immunity, and may also have a direct link to the nervous system, which is why it is sometimes called the ‘second brain’ (2-4).

It’s therefore important to treat your microbiota well by introducing friendly bacteria into your digestive system. There are two complementary ways of achieving this:

• ingest these microorganisms directly in the form of probiotics. The most widely-studied of these include Bifidobacterium and Lactobacillus bacteria, as well as Saccharomyces yeasts;
• stimulate the growth of good bacteria by nourishing them with the right compounds - prebiotics.

Dairy products, packed with lactic bacteria

Yogurt, produced using a culture of lactic bacteria (typically Streptococcus thermophilus and Lactobacillus bulgaricus, as well as Bifidobacterium for those containing bifidus), delivers a welcome shot of probiotics at the end of a meal (5). Opt for classic natural farm yogurt over highly-processed products (such as fruit varieties).

How about cheese? Certain aged varieties or those made with unpasteurised milk are notable for their high probiotic content, such as gouda, mozzarella, cheddar, gruyere and Roquefort (6). Lighter options, such as fromage blanc and cottage cheese, are good alternatives.

Fermented drinks, allies of a healthy microbiota

 For a sparkling drink that’s rich in natural probiotics, fermented beverages offer a healthy alternative to fizzy pop.

Consumed in the Caucasus since antiquity, kefir is made from the fermentation of animal milk activated by kefir seeds, a combination of lactic bacteria and yeasts (7). It is also available as fruit kefir, with a base of fruit juice, sugar and spices.

Very popular in Asia, kombucha is produced from a curious fungus of the same name (it’s actually a symbiotic colony of bacteria and yeast known as SCOBY) introduced into tea and sugar (8). The result is a fizzy, acidic and slightly alcoholic beverage.

Lacto-fermented vegetables, probiotics in jars

Sauerkraut, kimchi, cornichons, pickles … All these vegetables have undergone lacto-fermentation. This preserving process is based on the conversion of carbohydrates into lactic acid by the lactic bacteria in foods. This reaction gives them their distinctive acidity.

Apart from protecting food from pathogenic organisms, lactic fermentation provides an easy way of boosting your intake of probiotics (9). There’s no need to consume a large amount: 1-2 tbsps a day is sufficient.

Fermented soya, Asia’s microbiotic star

Used in all Asian cuisine sauces, where they deliver the exquisite taste of umami, fermented soya products also contain a wealth of probiotics (10).

In Indonesia, meat can be easily substituted by tempeh (hulled soya beans fermented by Rhizopus oligosporus mould). Miso, a fermented paste made from soya, rice and barley, is added to Japanese soups at the last minute. And soy sauce is great for zhuzhing up marinades (but use it sparingly as it’s very salty!)

Brewer’s yeast, the flora-friendly fungus

Brewer’s yeast contains a microscopic fungus called Saccharomyces cerevisiae. Used in the production of beer, its inactive form is available as flakes for sprinkling on food or drinks. Apart from its probiotic content, it also contains a number of B group vitamins, proteins and various trace-elements (chromium, selenium…) (11).

Fibre, an essential source of prebiotics

To proliferate effectively, good bacteria need to be fed! Dietary fibre, which does not cross the intestinal wall, is a form of non-digestible sugar which ferments in the gut and supports the growth of beneficial microorganisms.

This valuable source of prebiotics is primarily found in the plant kingdom. Good fruit and vegetable sources include asparagus, garlic, onions, leeks, artichokes and bananas (12). A vegetable that’s often overlooked, chicory is also well worth adding to the menu for its inulin content, a fructan-type fibre. Last but not least, fibre-containing pulses and whole grains should also feature prominently in your diet.

A word of advice: if you’re not used to eating this much fibre, increase your intake very gradually to prevent intestinal discomfort.

Microbiotic supplements to optimise your intake

You also have the option of boosting your daily intake of microorganisms by taking supplements targeted at the microbiota. The following all provide excellent microbiotic support.

Lactobacillus gasseri

One of the best-known strains, scientifically studied since the 1980s, Lactobacillus gasseri is a type of lactic bacteria naturally present in breast milk. Many studies have examined how it interacts with human metabolism (13-14).

To obtain maximum benefit, choose an adequately-dosed supplement in a form that withstands stomach acidity (such as Lactobacillus gasseri, gastro-resistant capsules that provide 12 billion microorganisms a day).

Colon Friendly

As each strain has its own sphere of activity, certain microbiotic formulations combine several microorganisms designed to colonise different areas of the digestive tract. For example, Lactobacillus acidophilus is concentrated in oral and digestive mucous membranes, while Saccharomyces cerevisiae has a particular affinity for the lower gastrointestinal tract.

That’s why they’re combined in innovative and powerfully synergistic supplements (such as Colon Friendly, a formulation containing the four well-known strains Saccharomyces cerevisiae, Bifidobacterium longum infantis, Bifidobacterium longum longum and Lactobacillus acidophilus) (15-16).

H. Pylori Fight

Unfortunately, not all strains of bacteria are friendly. A case in point is Helicobacter pylori, one of the few strains able to withstand the acid environment of the stomach, often responsible for heartburn and stomach ulcers (17).

A number of studies have investigated the interaction between beneficial and pathogenic bacteria. Equipped with adhesion molecules capable of co-aggregating to H. pylori, the inactivated DMS 17648 strain of Lactobacillus reuteri (which features in the patented supplement H. Pylori Fight) offers particular promise (18-19).

Probio Forte

When it comes to microbiotic supplements, the method of manufacture is key. It governs how the probiotics are placed in a state of dormancy. The most common method, atomisation, involves significant exposure to stress, which inevitably means some of the microorganisms will not survive (20).

Though more expensive, freeze-drying provides the microorganisms with more stability on their journey to the gastrointestinal tract (the supplement Probio Forte, combining 3 lactobacilli with Bifidobacterium lactis and Lactococcus lactis, uses this cutting-edge method).

Lactobacillus Plantarum PostBiotic

Have you come across postbiotics? Unlike classic probiotics, these contain microorganisms inactivated by heat treatment to remove their inhibitors, thus maximising their effect.

Discovered in narezushi, a type of fermented sushi, the Lactobacillus plantarum strain L-137 makes such effective use of this heat inactivation that it is regarded as the no. 1 immunobiotic (it can be found in the innovative microbiotic supplement Lactobacillus Plantarum PostBiotic, supported by several clinical studies) (21-22).