Probiotics: What Are They and How Do You Choose?

What is it?

Probiotics are live microorganisms, typically bacteria or yeast, that are consumed with the intention of maintaining or restoring a balanced microbial environment in the body. The most common genera used in supplements and foods are Lactobacillus and Bifidobacterium, as well as the yeast Saccharomyces boulardii. These microorganisms are naturally present in the human digestive tract and in certain fermented foods.

Probiotics are often referred to as "good" or "friendly" bacteria. They are found in a variety of foods such as yogurt, kefir, sauerkraut, kimchi, miso, and tempeh, as well as in dietary supplements.

Probiotics are live microorganisms that can be found in both foods and supplements.

The term "probiotic" is derived from the Greek words "pro" (for) and "bios" (life), reflecting the concept that these microorganisms are intended to support life by contributing to a balanced microbial ecosystem.

Probiotics are distinguished from other microorganisms by their ability to survive passage through the digestive system and reach the gut in sufficient numbers. Not all bacteria or yeast found in food are considered probiotics; only those strains that have been specifically identified and studied for their ability to survive and remain viable in the human body are classified as such.

In addition to their presence in foods, probiotics are manufactured and sold as dietary supplements in a variety of forms, often with specific strains and concentrations listed on the packaging. The diversity of strains and products on the market reflects the complexity of the human microbiome and the ongoing research into the potential roles of different microorganisms.

Authorised health claims

Within the European Union, only specific health claims for probiotics are authorised. As of now, there are no general health claims approved for probiotics regarding the maintenance of normal gut flora, digestion, or immune function.

Any probiotic product making a health claim must use the exact wording approved by the European Food Safety Authority (EFSA) and only for the specific strain and condition for which the claim is authorised. For most probiotic strains, there are currently no authorised health claims.

The process for authorising a health claim involves rigorous scientific assessment, including human studies demonstrating a clear, beneficial physiological effect.

Consumers should be aware that the presence of the term "probiotic" on a label does not imply any specific health benefit unless such a benefit is explicitly stated and authorised. The regulatory framework is designed to protect consumers from misleading claims and to ensure that any health-related information is based on robust scientific evidence.

Only specific, authorised health claims may be used for probiotics in the EU.

Key limitations

• No probiotic supplement or food should be used as a substitute for a varied and balanced diet.
• Individual responses to probiotics can vary, and the effects of one strain cannot be assumed for another.
• Scientific evidence for many claimed effects of probiotics is still under review, and most claims are not authorised.

It is important to understand that probiotics are regulated as foods or food supplements, not as medicines. This means that they are not subject to the same rigorous testing for efficacy and safety as pharmaceutical products.

The effects of probiotics are highly strain-specific. Even within the same species, different strains may have different properties and potential uses. For example, Lactobacillus rhamnosus GG and Lactobacillus rhamnosus GR-1 are genetically distinct and may not have the same effects in the body.

Furthermore, the human microbiome is complex and influenced by factors such as diet, age, genetics, and environment. This complexity means that the impact of consuming probiotics can vary widely between individuals.

Probiotics should not be relied upon as a primary means of maintaining health. Instead, they may be considered as one component of a broader approach to well-being that includes a balanced diet, regular physical activity, and other healthy lifestyle choices.

Forms and alternatives

Probiotics are available in several forms, each with its own characteristics. The choice of form may depend on personal preference, dietary restrictions, or specific product features.

Form	Common Examples	Typical Use	Storage
Capsules/Tablets	Supplements with measured strains	Oral, daily or as directed	Room temperature or refrigerated
Powders	Single or multi-strain blends	Mixed with water or food	Often refrigerated
Fermented Foods	Yogurt, kefir, sauerkraut, kimchi, miso	As part of meals	Refrigerated
Chewables/Liquids	Children's supplements, drinks	Oral	Varies

Capsules and tablets are among the most common forms of probiotic supplements. They are convenient, portable, and often contain specific strains and concentrations, which can be important for those seeking a particular product profile. Some capsules are designed with enteric coatings to help the microorganisms survive the acidic environment of the stomach and reach the intestines.

Powdered probiotics are typically mixed with water, juice, or food. This form may be preferred by individuals who have difficulty swallowing pills or who want to adjust the dose more flexibly. Powders may also be used in infant formulas or as additives in certain foods.

Fermented foods are a traditional source of live microorganisms. The types and amounts of microorganisms in these foods can vary widely depending on the preparation method, storage, and other factors. Not all fermented foods contain live probiotics at the time of consumption, as some may be pasteurised or processed in ways that reduce the number of viable organisms.

Chewable tablets and liquid formulations are often marketed for children or individuals who prefer not to take capsules. Some probiotic drinks are also available, which may contain added sugars or flavours.

Alternatives to probiotics include prebiotics and synbiotics. Prebiotics are non-digestible food components, such as certain fibres, that serve as food for beneficial microorganisms in the gut. Synbiotics are products that combine probiotics and prebiotics, aiming to support the survival and activity of the introduced strains.

It is important to note that the stability and viability of probiotics can be affected by factors such as temperature, humidity, and exposure to light. Some products require refrigeration to maintain potency, while others are formulated to be shelf-stable. Always check the manufacturer's instructions regarding storage.

How to choose

When selecting a probiotic product, consider the following factors:

• Strain specificity: Effects of probiotics are strain-specific. Check the label for the exact strain(s) included.
• Colony-forming units (CFU): This indicates the number of live microorganisms per dose. Products typically range from 1 billion to 50 billion CFU per serving.
• Product form: Choose a form that fits your lifestyle and dietary needs (see table above).
• Storage requirements: Some probiotics require refrigeration, while others are shelf-stable. Follow the manufacturer's instructions.
• Quality and certification: Look for products that have been tested for quality and purity by independent organisations.

When comparing products, review the strain, CFU count, expiration date, and storage needs. For those with dietary restrictions, check for allergens or animal-derived ingredients.

Some products may contain additional ingredients such as prebiotics (inulin, fructooligosaccharides), flavourings, or sweeteners. If you have sensitivities or allergies, read the ingredient list carefully.

It is also advisable to consider the manufacturer's reputation and whether the product has undergone third-party testing for potency and purity. Certifications from recognised organisations can provide additional assurance of quality.

Labels should clearly indicate the genus, species, and strain of each microorganism, as well as the number of live organisms guaranteed at the time of consumption (not just at the time of manufacture). Some products may list the CFU count per serving, while others may provide this information per capsule or per gram.

Expiration dates are important, as the viability of probiotics decreases over time. Using products before their expiration date helps ensure that you are consuming the intended number of live microorganisms.

Dosage and use

There is no universal recommended daily intake for probiotics. Dosage varies depending on the product, the specific strains used, and the intended use. Most supplements provide between 1 and 20 billion CFU per serving, but some products offer higher amounts.

• Follow the manufacturer's instructions for dosage and storage.
• Probiotics are often taken with food, but some products may recommend taking them on an empty stomach. Check the product label for guidance.
• Consistency is important; regular use may be necessary to maintain the presence of live cultures.

Consult a healthcare professional before starting any supplement, especially for children, pregnant or breastfeeding individuals, or those taking medication.

The timing of probiotic intake can influence the survival of the microorganisms. Some studies suggest that taking probiotics with a meal or shortly before eating may help protect the organisms from stomach acid, increasing the likelihood that they reach the intestines alive. However, recommendations vary by product and strain.

It is important to use the product as directed and not to exceed the recommended dose. Higher doses do not necessarily result in greater effects, and the safety of very high doses has not been established for all strains.

For those using probiotics in the form of fermented foods, serving sizes and microorganism content can be highly variable. Unlike supplements, foods may not provide a standardised dose, and the number of live organisms can decrease over time or with processing.

Probiotics are sometimes used for limited periods (such as during travel or after antibiotic use), but long-term use is also common. The duration of use should be based on individual needs and professional advice.

Safety, interactions and risk groups

Probiotics are generally considered safe for healthy adults when used as directed. However, certain groups should exercise caution:

• Pregnant or breastfeeding individuals should seek medical advice before using probiotics.
• Children should only use probiotics under the supervision of a healthcare provider.
• Some probiotics may interact with medications or other supplements. Always inform your healthcare provider about all products you are taking.

Side effects are uncommon but can include mild digestive symptoms such as gas or bloating, especially when starting use. If you experience persistent or severe symptoms, discontinue use and consult a healthcare professional.

These cases are uncommon, but highlight the importance of professional guidance for at-risk groups.

Probiotic supplements may also contain allergens such as dairy, soy, or gluten, depending on the manufacturing process. Individuals with food allergies or intolerances should check product labels carefully.

The safety of probiotics during pregnancy and breastfeeding is not fully established for all strains. While some products are marketed for these groups, it is essential to consult a healthcare provider before use.

Interactions between probiotics and medications are not well documented, but there is potential for certain strains to affect the absorption or metabolism of drugs. Always inform your healthcare provider about any supplements you are taking.

Proper storage is important to maintain the safety and effectiveness of probiotic products. Exposure to heat, moisture, or light can reduce the number of viable organisms and increase the risk of spoilage.

Regulation and labelling

Probiotics are regulated as foods or food supplements in the European Union and many other regions. This means that they must comply with food safety standards, including requirements for labelling, hygiene, and quality control.

Labels must accurately reflect the contents of the product, including the genus, species, and strain of each microorganism, the number of live organisms at the end of shelf life, recommended storage conditions, and any allergens present.

Manufacturers are responsible for ensuring that their products are safe and that any claims made are truthful and not misleading. The use of the term "probiotic" itself is regulated, and in some countries, it may not be permitted on labels unless supported by authorised health claims.

Consumers can check for certifications or seals from independent organisations, which may indicate that the product has been tested for quality and purity. However, these certifications are voluntary and not a guarantee of efficacy.

It is advisable to purchase probiotic products from reputable sources and to be cautious of products making unsubstantiated or exaggerated claims.

Storage and shelf life

The viability of probiotics depends on proper storage. Many probiotic strains are sensitive to heat, moisture, and oxygen, which can reduce their numbers over time.

Some products require refrigeration to maintain potency, while others are formulated to be stable at room temperature. Always follow the manufacturer's storage instructions to ensure that you are consuming the intended number of live microorganisms.

Check the expiration date before use. The number of live organisms in a product may decrease as it approaches or passes its expiration date, potentially reducing its effectiveness.

Improper storage, such as leaving a product in a hot car or in direct sunlight, can accelerate the loss of viability. If a product has an unusual odour, appearance, or texture, it should not be consumed.