Probiotics: what does the science say?

Probiotics: what does the science say?

Probiotics are everywhere. In yoghurt, in capsules, in your Instagram feed. The promise sounds enticing: better digestion, a stronger immune system, even better skin. But what does the science actually say? Do they really work, or is it mostly marketing?

Let's lay out the facts.

What exactly are probiotics?

Probiotics are living micro-organisms - mainly bacteria and yeasts - that provide a health benefit when consumed in sufficient quantities. They're the "good" bacteria that naturally live in your gut.

Your gut flora (or microbiome) contains an estimated 100 trillion micro-organisms - that's more than the number of cells in your entire body. This complex ecosystem plays a crucial role in:

• Digestion and nutrient absorption
• Immune system - 70% of your immune defences are in your gut
• Mental health via the gut-brain axis
• Vitamin production (B12, K2)
• Protection against harmful bacteria

The science: what's been proven?

Not all probiotic claims are equally well supported. Here's what we know with certainty:

Strong evidence

Antibiotic-associated diarrhoea This is the best-studied benefit. Multiple meta-analyses show that probiotics - particularly Saccharomyces boulardii and Lactobacillus rhamnosus GG - significantly reduce the risk of diarrhoea during and after antibiotic courses. The Belgian Superior Health Council recognises this use.

Irritable Bowel Syndrome (IBS) For people with IBS, specific strains can alleviate symptoms. Bifidobacterium infantis 35624 and Lactobacillus plantarum 299v have demonstrated in clinical trials that they improve bloating, abdominal pain and irregular bowel movements.

Traveller's diarrhoea Those travelling to regions with lower hygiene standards may benefit from preventive probiotic use. The evidence is moderate but positive.

Emerging evidence

Immune system Multiple studies suggest that probiotics may reduce the duration and severity of colds, especially in children. Evidence is growing but not yet definitive.

Skin health The gut-skin axis is a growing field of research. There are indications that probiotics may help prevent eczema in babies and strengthen the skin barrier. Lactobacillus rhamnosus specifically shows promising results.

Mental health So-called "psychobiotics" are hot in research. Early studies point to a connection between gut flora and anxiety, depression and stress. Promising, but we're not there yet.

Insufficient evidence

• Weight loss
• Cancer prevention
• Cholesterol reduction

These claims regularly appear in marketing, but the scientific evidence is currently insufficient to make strong statements.

Not all probiotics are equal

This is perhaps the most important point. Probiotics are strain-specific. This means:

• Lactobacillus acidophilus NCFM does something different from Lactobacillus acidophilus LA-5
• What's proven for strain X doesn't automatically apply to strain Y
• The brand and formulation matter

Pay attention to:

1. Specific strains - Not just "Lactobacillus" but the complete strain number
2. CFU count - Colony Forming Units, i.e. the number of living bacteria. Look for at least 1 billion CFU per dose
3. Survival rate - The bacteria must survive your stomach acid. Enteric-coated capsules help with this
4. Storage instructions - Some probiotics need refrigeration, others are stable at room temperature

Food probiotics vs. supplements

You can get probiotics in two ways:

Through food

• Yoghurt with live cultures
• Kefir - one of the richest natural sources
• Sauerkraut (unpasteurised)
• Kimchi
• Kombucha
• Miso

The advantage of food sources: they offer a broad spectrum of bacterial strains plus prebiotics (food for the good bacteria).

Through supplements

Supplements are useful when:

• You need specific strains for a specific problem
• You're on an antibiotic course
• Your diet doesn't include enough fermented products
• You're travelling

At your Belgian pharmacy, you'll find a wide range of probiotic supplements. Your pharmacist can advise you on which strains and dosages best suit your situation.

Prebiotics: the forgotten sibling

Just as important as probiotics are prebiotics - the fibres that serve as food for your good gut bacteria. Without prebiotics, probiotics have little chance of thriving.

Good sources of prebiotics:

• Inulin (chicory, artichoke, onion, garlic)
• FOS (fructo-oligosaccharides) - found in banana, asparagus, wheat
• Resistant starch - cooled potatoes, green banana

Interesting fact for Belgians: chicory is one of the richest sources of inulin in the world. Yet another reason to put this Belgian gem on your plate.

Frequently asked questions

Can I take too many probiotics? Side effects are rare and usually mild (slight bloating at first). But more isn't always better. Follow the recommended dosage.

When is the best time to take probiotics? Preferably on an empty stomach or just before a meal. Stomach acid concentration is then at its lowest and more bacteria survive the passage.

How long should I take probiotics? For acute situations (after antibiotics): minimum 2-4 weeks. For chronic complaints: at least 3 months to assess effectiveness.

Are probiotics safe for everyone? For most people, yes. Be cautious with a severely weakened immune system or after major surgery. Always consult your doctor in those cases.

The bottom line

Probiotics aren't a miracle cure, but for specific applications the scientific evidence is compelling. The key is choosing the right strain for the right problem, rather than blindly following marketing claims.

Talk to your pharmacist about which probiotics suit your situation. And don't forget the basics: a varied diet with sufficient fibre is the best gift you can give your gut flora.

Disclaimer: This article is for informational purposes and does not replace medical advice. Consult your doctor for serious digestive issues.