Last updated on August 6, 2021.
The popularity of probiotics can be dated back to the 1980s. At that time, lactic acid bacteria were mostly used for probiotics research, which were then brought to the public eye by a showcase of fermented foods on the market that contain probiotics, such as Korean kimchi, Japanese miso (soybean paste) and natto (fermented soybeans). These days, many people turn to supplement probiotics to improve their immunity and to prevent viral infection. If you are not a fan of supplements, probiotics are readily available in many foods as well, from yogurt to fermented foods.
What are probiotics?
Probiotics generally refer to live microorganisms beneficial to the human digestion and immunity systems. They exist in forms of yeasts or bacteria and can be found in yogurt and fermented foods, as well as in dietary supplements. The most widely known probiotics are lactic acid bacteria and bifidella. After ingestion, the anaerobic and nutritious environment in the intestines favors the breeding of probiotics to enhance the biodiversity of gut microbiota and bring multiple health benefits.
In terms of digestive health, recent research revealed that it is not the amount or specific type of probiotics intake that matters, but the diversity of probiotics strains.
Are prebiotics the same as probiotics?
No, they are not. Prebiotics are essential elements for probiotics as they stimulate the growth and activity of beneficial probiotic bacteria. They are the non-digestible components in food, for example fiber in vegetables and fruits.
What are the functions of probiotics?
“You are what you eat.” The functions of your body are provided by the food you eat. Therefore, maintaining a healthy digestive system is a key to obtaining the required nutrients, because the gastrointestinal tract is responsible for breaking down and absorbing all the nutrients in the food and supplements you eat. An imbalanced gastrointestinal environment will disrupt this process, leading to a vicious circle, and affect your health. A review article written by Monash University stated that diseases linked to a disrupted gut microbiota include colorectal cancer, heart disease, metabolic syndrome, type 2 diabetes, obesity, Alzheimer’s disease and depression.
Probiotics can balance the gastrointestinal environment and help you maintain your health. They are considered to be the “good” bacteria that help digest food, fight against infectious foreign substances and help produce vitamins (e.g. vitamin K).
Health benefits of probiotics
Probiotics exhibit the ability to destroy infectious bacteria in the intestines as a natural body defense mechanism to protect our immune system.
However, use of antibiotics and other drugs, poor eating habits and certain diseases can lead to imbalances in the gut microbiota, and cause digestive problems. A study by the Southern California Evidence-Based Practice Center found that probiotics can reduce diarrhea caused by antibiotics. After probiotics enter the intestines, they begin to compete with the “bad bacteria” for resources and grow. With less resources available for “bad” bacteria, they gradually decline in number. Thus, probiotics help restore the balance of “good” and “bad” bacteria in the intestines.
Probiotics can bring about weight loss by influencing fat metabolism and appetite control. A randomized controlled trial conducted by a Canadian university found that women who took Lactobacillus rhamnosus, a type of probiotics, for 3 months lost 50% of their weight compared to women who did not take it. Another study showed that participants taking Lactobacillus gasseri, another type of probiotics, daily lost an average of 8.5% of their belly fat in 12 weeks.
The proposed mechanism is that some probiotics block the absorption of fat in the intestines, causing fat to be excreted through bowel movements instead of being stored in the body. Another explanation is that probiotics can sustain fullness for a long period of time and reduce appetite by releasing appetite-regulating hormones (e.g. glucagon-like peptide-1 and peptide YY), which can even help burn calories and fat, leading to weight loss.
However, not all probiotics can help weight loss. Studies have found that Lactobacillus acidophilus can cause weight gain, while some probiotics may have been destroyed by gastric acid before reaching the intestines.
Probiotics are associated with the reduced risk of many different diseases, for example, cancer, obesity and Alzemer’s disease.
In particular, psychobiotics is an emerging group of bacteria that affect the function of the gut-brain axis, which links the body’s central and intrinsic nervous systems (the latter controls digestion). Recent research explored the potential role of psychobiotics in reducing cognitive diseases, such as Alzheimer’s disease and Parkinson’s disease.
Eczema is a common skin condition caused by a defective immune system reaction, resulting in dry, inflamed skin that may crack and bleed. Probiotics helps maintain a healthy immune system to fight against the defective immune response that causes eczema. Although there are mixed research results on the effect of probiotics as an eczema treatment, numerous studies show positive clinical outcomes. Altogether, probiotics is best used as a complementary medicine together with the existing eczema treatment, but not a replacement.
Other health benefits
Some research stated that probiotics can help with the following conditions:
- upper respiratory infections & ear infections (e.g. common cold)
- oral health
- irritable bowel syndrome/ inflammatory bowel disease
- infectious diarrhea
- lactose intolerance
- skin health, e.g. eczema and acne
- urinary and vaginal health
- blood pressure
- blood cholesterol
- depression and anxiety
Foods that contain probiotics
Here are some examples of probiotics foods for your everyday meal to optimize your gut health and immunity!
Yogurt is fermented from milk, and it contains lactic acid bacteria and bifidella.
Yogurt may even be suitable for people with lactose intolerance, as the bacteria in yogurt may be able to convert lactose into lactic acid.
Fermented cheese, such as Cheddar, Gouda and Cottage cheese contain probiotics.
Vegetables pickled in brine, such as olive, Korean kimchi, pickled cucumber and sauerkraut (German shredded cabbage) are rich in lactic acid bacteria.
Dark chocolate can cultivate the growth of active intestinal probiotics in the body.
Miso is fermented from soybeans, so it also contains probiotics.
Korean kimchi is a fermented cabbage which contains lactic acid bacteria that benefit digestive health.
Natto is another fermented soybean product that originated from Japan. It contains Bacillus subtilis as the source of probiotics
Any special considerations when choosing probiotics supplements?
Harvard Women’s Health Watch stated that when purchasing probiotic supplements, consumers should pay attention to the CFU value (number of probiotic bacteria) in the supplements. Usually a daily dose of probiotic supplements for adults contains 1 billion to 10 billion, but the exact amount depends on the type of probiotic strain, age and purpose of the user, and microbial activity of the probiotic bacteria.
Are probiotics supplements suitable for everyone?
Not all probiotics supplements are suitable for everyone. You must choose the appropriate probiotics according to your physical condition. In particular, people with severe diseases or impaired immune systems, people with allergies, pregnant women, breastfeeding women or people who are taking medication, should pay attention to the ingredients of the supplements. The above-mentioned people should consult their doctors before taking any kind of supplement.
What are the side effects of probiotics supplements?
Only some people experience mild gastrointestinal discomfort, such as bloating, gas and nausea, when they start to take probiotics supplements. These symptoms normally fade away in a few days. But if they continue to appear, stop the supplementation and consult a doctor.
Some people have to be more cautious when using probiotic supplements, particularly:
- people with a weakened immune system (e.g. undergoing chemotherapy)
- people with serious illness
- post-surgery patients
- sick infants