1. Definition of Probiotics
Probiotics are active microorganisms that can positively affect health by improving and regulating the gut microbiota. Strictly speaking, most probiotics belong to lactic acid bacteria, but not all lactic acid bacteria are probiotics; there are also a few non-lactic acid strains that have been scientifically proven to have beneficial effects.
Scientifically, six criteria are generally used to determine whether a bacterium can be considered a probiotic: its safety, ability to colonize the gut, beneficial effects on the host, inhibition of harmful bacteria, tolerance to the digestive environment, and evidence of effectiveness through clinical or experimental studies.
Probiotics can colonize and multiply in the gut, working synergistically with other beneficial microbes to enhance their number and activity. Beneficial bacteria produce organic acids that lower intestinal pH, as well as hydrogen peroxide and natural antibiotics that inhibit the growth of harmful bacteria and toxic substances. This creates an optimal gut environment, which not only helps eliminate harmful microbes but also strengthens immunity, reduces the risk of infections and diseases, and provides comprehensive support for overall health.
2. Common Probiotics
To date, discovered probiotics can generally be divided into three categories:
- Lactic Acid Bacteria, such as Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus rhamnosus, etc.
- Bifidobacteria, such as Bifidobacterium longum, Bifidobacterium breve, etc.
- Gram-positive cocci, such as Streptococcus and Lactococcus.
On the market, probiotic products mainly include yogurt, fermented milk, soy yogurt, oral liquids, capsules, and powders.
3. Suitable Groups
(1) People who may benefit from probiotics:
- Infants delivered by cesarean section, premature infants, low birth weight infants, or formula-fed infants: These children often have weaker immunity and are prone to frequent colds or intestinal infections.
- People with diarrhea or constipation: Whether caused by bacteria, viruses, protozoa, or non-infectious factors, gut microbiota imbalance is common.
- Cancer patients undergoing chemotherapy or radiotherapy: These treatments kill beneficial bacteria, leading to gut dysbiosis, bloating, constipation, nutrient loss, and toxin absorption, which may affect recovery or interrupt treatment.
- Patients with cirrhosis or peritonitis: These individuals often have gut dysbiosis and varying degrees of endotoxemia. Probiotics can inhibit harmful amine-producing bacteria, reduce intestinal acidity, and lower blood endotoxin levels.
- Patients with enteritis: For conditions like ulcerative colitis, probiotics can provide some therapeutic benefits.
- People with digestive disorders: Functional dyspepsia presents as recurrent or persistent upper abdominal bloating, loss of appetite, or heartburn without other gastrointestinal disease. Probiotics can promote digestion.
- Individuals with lactose intolerance ("milk allergy"): A congenital or acquired deficiency of lactase can cause bloating and diarrhea because lactose cannot be properly broken down. Probiotics help digest lactose in milk and improve nutrient absorption.
- Middle-aged and elderly people: Levels of beneficial bacteria like Bifidobacteria decline with age. Supplementing probiotics can serve as a preventive health measure.
4. Benefits of Probiotics
(1) Improve Constipation and Diarrhea
Probiotics, a type of lactic acid bacteria, can break down lactose and produce lactic acid. Lactic acid helps regulate gut pH, inhibit harmful bacteria, and promote the growth of beneficial microbes, maintaining gut microbiota balance. This balance supports gut health and normal intestinal metabolic function, fundamentally improving constipation, diarrhea, and other common gut issues while aiding digestion.
Regular intake of probiotics can naturally regulate the gut environment, stabilize intestinal function, enhance digestion and absorption, reduce discomfort, and support overall health.
(2) Immune Regulation
The immune system defends the body against pathogens, with the gut being a critical component. Daily microbial interactions in the gut engage with the host's immune system to maintain health. Research shows that probiotics can enhance the activity of macrophages and natural killer (NK) cells, as well as increase immunoglobulin levels, thereby strengthening overall immunity.
NK cells are an important indicator of immune function. Low NK cell levels make individuals more susceptible to infections and may increase cancer risk. Aging also reduces NK cell numbers, weakening immunity. Supplementing probiotics can activate and maintain NK cell function, helping the body resist infections and maintain health.
(3) Reduce the Risk of Colon Cancer and Other Cancers
Studies suggest that diet is closely linked to cancer risk. Unhealthy long-term eating habits can significantly increase disease risk. Conversely, probiotic-rich foods can help lower cancer risk by regulating gut microbiota, optimizing the intestinal environment, and enhancing immune system function. This allows immune cells to better recognize and eliminate abnormal or precancerous cells, contributing to health protection.
Reasonable intake of probiotics helps maintain gut balance and digestive health and may serve as a nutritional strategy to reduce cancer risk. However, probiotics are not a standalone treatment but an important part of a healthy diet and lifestyle.
(4) Reduce Lactose Intolerance
In Asia, lactase activity in the gut is relatively low, leading to primary lactose intolerance in about 80% of people. Mild cases cause bloating or rumbling, while severe cases result in nausea and diarrhea. Supplementing with lactic acid bacteria-containing foods like yogurt can help, as these bacteria provide lactase and metabolize 20–40% of lactose in milk, alleviating intolerance symptoms.
(5) Mitigate the Harm of Antibiotics
While antibiotics effectively treat infections, they also kill beneficial bacteria, creating space for harmful bacteria to proliferate and potentially compromising health. Therefore, doctors often recommend probiotics alongside antibiotic treatment to replenish beneficial bacteria, protect the gut, and maintain immune system function.
(6) Prevent Food Poisoning
Even with modern food safety measures, foodborne pathogens remain a threat. Many harmful bacteria cannot survive in acidic environments. Probiotics produce lactic acid, increasing gut acidity, which creates an environment hostile to pathogens and helps prevent food poisoning.