The Science Behind Probiotic Foods and the Microbiome

What Are Probiotic Foods?

Simply put, probiotic foods are those that contain probiotics. These are live microorganisms that naturally form part of the gut microbiome. They include certain yeasts and lactic acid bacteria, particularly various Lactobacillus strains and the highly effective Bifidobacteria. So, probiotic foods contain microorganisms that also reside in our gut.

What Health Benefits Do Probiotics Offer?

Probiotics help keep your gut in balance. Although there is no definitive scientific proof that probiotic foods directly improve gut health, it’s clear that beneficial microorganisms play an important role in the gut. As part of the helpful bacteria in the gut, probiotics contribute to gut function once they arrive in the intestines.

A balanced gut microbiome supports the immune system by helping it fend off threats, thus boosting immunity. Additionally, beneficial gut bacteria play a crucial role in healthy digestion.

Why Can’t Food Manufacturers Promote Probiotics’ Benefits?

The European Food Safety Authority (EFSA) has not found sufficient scientific evidence to support claims that probiotic foods have direct health benefits. As a result, it has not approved most probiotic products for inclusion on the list of authorised health claims. So far, EFSA has only recognised the benefits of three specific lactic acid bacteria strains.

One of the reasons for scepticism is that not all beneficial microorganisms in food survive the journey to the gut. Only yeasts and bacteria that are resistant to stomach acid can make it through and exert their positive effects.

How Do Probiotics Work in the Gut and Why Are They Important for Gut Health?

Among the trillions of microorganisms in our gut, there are both beneficial and harmful ones. The good bacteria ensure that harmful ones don’t dominate. This balance means the gut microbiome has a significant impact on the body, promoting healthy digestion and supporting the immune system.

When you consume foods containing stomach-acid-resistant probiotics, you introduce more beneficial yeasts and bacteria into your gut. This increases the proportion of helpful microorganisms and helps them keep harmful ones in check. Key probiotic strains include Bifidobacteria and Lactobacillus.

Probiotics vs. Prebiotics: Differences and Shared Benefits

When discussing probiotics, the term "prebiotics" often comes up. There’s a connection between them, but also a key difference. Prebiotics aren’t microorganisms. Instead, they serve as food for gut bacteria or support them in other ways.

Prebiotics are a type of fibre, the non-digestible parts of food. They pass through the digestive system to the gut, where they promote the growth of probiotics. Vegetables like salsify, garlic, chicory, and onions are typical prebiotic-rich foods. Some foods contain both prebiotics and probiotics, offering a synergy known as synbiotics.

The Best Foods With Probiotics

Lactic acid bacteria, particularly Bifidobacteria, are the most common probiotics, found mainly in fermented dairy products, fermented vegetables, and drinks. While probiotics occur naturally in these foods, the food industry also adds them to certain products.

Here are some probiotic-rich foods:

• Kefir
• Yoghurt
• Skyr
• Ayran
• Cultured milk
• Buttermilk
• Cheeses like Harzer, Cheddar, Parmesan, Mozzarella, Bergkäse, Gouda, and Gruyère
• Sauerkraut
• Apple cider vinegar
• Lactic-fermented beetroot, carrots, and beans
• Lactic-fermented cucumbers and pickles
• Fermented soybeans (Tempeh)
• Miso paste made from fermented soybeans
• Fresh kombucha tea
• Kvass (fermented bread drink)
• Water kefir
• Lassi
• Kimchi (fermented vegetables)

Fresh yoghurt is especially high in lactic acid bacteria, so it’s a good idea to make your own. You can choose different yoghurt cultures, including ones with high probiotic content. With cheese, the older and more mature it is, the richer it is in lactic acid bacteria. Living microorganisms are only present in non-pasteurised foods. Make sure your pickles are lactic-fermented, not pickled in vinegar, as vinegar destroys the lactic acid bacteria, just like pasteurisation.

Who Should Be Cautious About Consuming Probiotic Foods?

While probiotics offer many benefits, they’re not suitable for everyone. There is still insufficient evidence on how they affect people with ulcerative colitis. Those with weakened immune systems should consume probiotic foods in moderation. People with acute pancreatitis or other serious abdominal inflammations, as well as those suffering from a stomach flu (gastroenteritis), should avoid probiotics altogether. In these cases, it’s important to consult a doctor before consuming probiotic foods.