On Probiotics, Prebiotics and Antibiotics

What’s the difference and why they all matter

Probiotics

These are live, beneficial bacteria that support digestion, gut health, immunity, and even mood.

You’ll often see them advertised on yogurts and drinks like Yakult. While those do contain probiotics, they’re also ultra-processed and often loaded with sugar or sweeteners.

A better choice is plain kefir or natural yogurts (like Greek yogurt), which provide live cultures without the additives.

Fermented foods such as yogurt, kefir, kimchi, and sauerkraut have an added advantage: their bacteria are naturally protected. In dairy, the protein and fat-rich matrix shields bacteria as they travel through the harsh stomach environment until they reach their home in the lower intestine. In vegetables like kimchi or sauerkraut, plant fibres and cell structures offer similar protection, helping more bacteria reach the intestines alive.

Prebiotics

Prebiotics are the food for your good bacteria and they’re even more important than probiotics. It’s no use adding new bacteria if you don’t feed them properly. A low-fibre, processed diet makes the gut an inhospitable place for beneficial microbes.

The good news? This can be turned around quickly… within a couple of days of eating the right foods.

Good bacteria thrive on dietary fibre from a wide range of whole foods: nuts, seeds, whole grains, fruits, and vegetables.

That’s why I always push fibre intake: aim for “5 a day” or 30 different plant foods per week. Fermented vegetables like kimchi and sauerkraut are especially powerful because they act as both a probiotic (live bacteria) and a prebiotic (fibre).

Without prebiotics, probiotics struggle. It’s prebiotic fibres that promote good bacteria growth and diversity, which in turn supports gut health and even mood. When starved, beneficial microbes may shrink in number, while harmful ones take over… releasing inflammatory compounds that can affect your behaviour and health.

A lack of fibre can also encourage bacteria to break down the gut’s protective mucus barrier, leading to increased intestinal permeability (“leaky gut”). This allows bacteria and toxins to slip into the bloodstream, placing strain on the liver, contributing to insulin resistance, and in some people triggering food sensitivities or autoimmune conditions such as ankylosing spondylitis or rheumatoid arthritis.

On the flip side, “bad” bacteria thrive on refined sugar and processed foods, while “good” bacteria thrive on fibre-rich, whole-food carbohydrates. For starchy foods, go wholegrain wherever possible.

Antibiotics

Antibiotics help you get better, but they come at a cost. Taking a course is like dropping an atom bomb in your gut wiping out both harmful and beneficial bacteria. This is why many people get digestive issues, like diarrhea, during or after treatment. That’s your dead bacteria coming out. 

Use antibiotics only when truly necessary and prescribed. If you do need them, focus afterward on rebuilding your gut ecosystem with fermented foods (kefir, yogurt, kimchi, sauerkraut) alongside a wide variety of high-fibre plant foods.

Unfortunately, antibiotics don’t just come from prescriptions. In some regions, particularly the US, livestock are given antibiotics to speed growth and prevent illness, which can leave residues in meat. Regulations are stricter in the UK and EU, but if you can, choose organic or grass-fed meat to reduce exposure. Balancing your diet with fish, legumes, and plants also helps.

Fun facts: A healthy adult gut contains around 30–100 trillion microbes (that’s bacteria, fungi, archaea, and viruses) and together they weigh as much as the brain. But the key is not numbers, its diversity.

Now go feed your gut.