Introducing the immune system
There are many bacteria and viruses around us and they can readily enter our bodies through the nose or mouth when we breathe or eat. A runny nose, coughing and sneezing are part of the mechanisms we have to repel invading bacteria, viruses, and other foreign matter from the body. We also have an ability called immunity that distinguishes between our own body and foreign matter, and eliminates the foreign matter for our protection. The body’s system of immunity is called the immune system.
Without an immune system, we would have no way to fight harmful things that enter our body from the outside or harmful changes that occur inside our body.
Three main tasks of the immune system are:
- to fight disease-causing germs (pathogens) such as bacteria, viruses, parasites or fungi, and to expel them from the body
- to recognize and neutralize harmful substances from the environment, and
- to fight foreign matter generated every day in the body such as cancer cells
The crosstalk between human intestines and immunity
The human intestines are not just an organ for digesting food and absorbing nutrients. 70% of the immune cells in the human body reside in the intestine, making it the body’s largest immune organ. Immune cells die and new ones are born every day. They do not have the strength to fight with enemies from the beginning, so they train themselves by gaining experience in the field and develop the strength to defeat bacteria, viruses and cancer cells. However, the cells cannot gain experience if the opposing forces are too strong. Since a great variety of bacteria dwell in the intestines, the intestinal bacteria train the immune cells by fighting with them in a well-balanced manner to gain experience.
Peyer’s patches and other lymphoid tissues where enemies and immune cells encounter each other are also located in the intestines and immune tissue that is unique to the intestines is also developed here. This is known as the gut-associated lymphoid tissue: GALT. In other words, the intestines not only digest food and absorb nutrients, it is also the largest immune organ in the body.
Scientific studies suggested that probiotics supplementation increased resistance towards harmful bacteria and viruses in the intestines and reduce tumor formation. There are evidences showing probiotic supplementation is able to alleviate allergic reactions and reduce the risk of infections, caused by both harmful bacteria and viruses.
The preventive measure – probiotics
Probiotics are living microorganisms that, will confer health benefits to the host, when ingested in adequate amount. Probiotics are friendly and helpful microorganisms that can be found naturally in the human intestines.
Probiotic capsules and powders can be easily bought from the pharmacies, and many are consuming these products on a regular basis as a type of health supplements. Other than purchasing probiotics over the counters, probiotics can also be found in the form of food and beverage. Fermented food such as yogurt, probiotic drink or cultured milk drink, kimchi, tempeh and miso are a few to mention.
Many studies have been conducted on probiotics showing their benefits on human health. Benefits suggested include weight loss, improved digestion, enhanced immune function, reduce risk of certain cancers and diseases. While there are many strains of probiotics available in the market, it is important to recognize the strain that you are consuming, to determine the health benefits that you may receive from the probiotics.
The Malaysian Ministry of Health has acknowledged the benefits of probiotics in the form of food and beverage under the Malaysian Food Act in 2017. Probiotics has been recognized to be able to improve overall gut function which indirectly regulate immune system too.
Yakult probiotic bacteria L.casei Shirota strain
Probiotic capsules or powders may be easily available in pharmacies but they might not be pocket-friendly. Yakult is a type of probiotic drink, founded in 1935 by a Japanese doctor, Dr. Minoru Shirota. Dr. Shirota created the cultured milk drink by using a unique probiotic strain, Lactobacillus casei Shirota strain, which is strong enough to withstand our digestive juices and to survive into our intestines.
The L.casei Shirota strain also commonly known as Shirota strain is one of the most studied probiotic strains and has been scientifically proven to have positive impacts on human health. Shirota strain is able to maintain the balance between harmful and beneficial bacteria in the intestines, regulate bowel movements to reduce constipation and diarrhea, reduce body toxins, and to boost immune function to reduce the risk of cancers. Every bottle of Yakult contains more than 30 billion live Shirota strain to maintain the health of our intestines and to boost our immune functions.
Shirota strain regulates immune cell – Natural Killer cells
The natural killer cells (NK cells) play an active role in natural immunity. They exist everywhere in the body. If cancer cells or virus-infected cells are found, NK cells launch attacks to repel them immediately.
The strength of NK cells attacking cancer cells and virus-infected cells is called NK cell activity. NK cell activity can be a barometer of immune strength. The strength of NK cell activity is known to greatly depend on various factors.
People aged 60 or above may have a lower NK cell activity than those aged 35 or younger.
A poor lifestyle such as smoking, unbalanced diet, lack of sleep, stress, excessive drinking and lack of exercise can result in obesity. It is said that obesity is associated with weakened immune strength.
A study was conducted in Japan with 105 male subjects ranging in age from 20 to 59 years old. Individuals reporting good lifestyle habit were found to have highest NK cell activity and it was significantly higher than then NK cell activity in those reporting poor lifestyle habits.
Morimoto K, et al. (2001)