You may be aware that probiotics are closely linked to the state of your digestive health. However, did you also know that good digestive health is also important to maintain a healthy immune system? Associate Professor Dr Raja Affendi Raja Ali, Consultant Physician and Gastroenterologist at the Hospital Canselor Tuanku Muhriz, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM) explains, "Your digestive system forms a large part of your immune system and is your body's first line of defence against infections. Around 80% of our body's immune system is centred in our gut."
It is therefore unfortunate that many Malaysians do not place much emphasis on their digestive health. Citing the poor state of digestive health among Malaysians as revealed in statistics from Health Facts 2017 from the Ministry of Health, Assoc Prof Dr Raja Affendi reveals, "Diseases of the digestive system were recorded as the fourth principal cause of hospitalisation in private hospitals, seventh principal cause of hospitalisation in government hospitals and sixth principal cause of death in both government and private hospitals."
It's a conglomerate
The immune system is made up of more than just one organ in your body. In order for it to work properly, it must be in balance and harmony with the rest of one's body. Having a healthy lifestyle is important as it forms the basis for a healthy immune system. A general guideline is not to smoke, eat a diet rich in fruits and vegetables, exercise regularly, maintain a healthy weight, get enough sleep and managing and minimising stress.
Probiotics and Immunity
As you may know, probiotics are the 'good' bacteria that form part of the collection of microorganisms known as the gut microbiota. It is important to maintain a proper balance between good and bad bacteria for good gut health and good immunity.
Probiotics such as Lactobacillus and Bifidobacteria are able to help maintain this balance. This is important as probiotics can positively affect the immune system of the host and may be effective against diseases caused by abnormalities in one's immune system.
"The good bacteria helps your immune system by forming a barrier on the intestinal wall (which prevents harmful microorganisms from easily infiltrating the mucosal barrier) and also modulates the response of the immune system to harmful external threats," remarks Assoc Prof Dr Raja Affendi.
While the exact mechanism by which probiotics interact is not completely clear, early studies of how probiotics affect immunity have provided scientists with some very encouraging results. Probiotics appear to be able to influence the immune system, apparently by regulating the production of cytokines. Cytokines are proteins secreted by cells in your body, which includes interferon (that prevents virus replication) and interleukin (that helps regulate immune responses).
"Probiotics can potentially affect the immune system in two main ways. Firstly, by activating immune cells such as phagocytes which prevent infections. Secondly, they help to prevent excessive immune system responses. This is believed to be the mechanism that potentially inhibits the cascade of inflammation that we seen in conditions like inflammatory bowel diseases (IBDs), allergies and autoimmune diseases," discloses Assoc Prof Dr Raja Affendi.
He went on to add that the main mechanisms that account for the anti-inflammatory activities include suppressing inflammation-causing cytokines such as:
- Interleukin-6 (IL-6) which can support the immune system or be a source of inflammation1,
- Interleukin-8 (IL-8) which has an important role in the development of inflammatory bowel disease, IBD2.
Thus, probiotics can have many different effects on our immune system. In fact, there are studies that revealed how probiotics actually regulate our immune system thus leading to an increase in immunity against diseases caused by a compromised (or abnormal) immune system.
Going global
Research on probiotics is happening globally, and many of these studies show a positive association between probiotics and immunity. In Europe, a study on children in day care revealed that regular daily intake of Lactobacillus would help decrease their risk of upper respiratory tract infections3.
Another study on healthy adults in America who had received an influenza vaccination followed by daily consumption of Lactobacillus showed enhanced immune response compared to healthy adults who did not consume probiotics4.
Just last year, a New Zealand study showed that a daily intake of probiotics would help reduce the duration and incidence of infections among elite rugby players5.
"These results show us that probiotics are able to help our immune system to deal with infections, especially those that spread via the mucosal membrane, such as the influenza virus. From this, it can be inferred that regular consumption of Lactobacillus is beneficial for potentially better immune responses," Assoc Prof Dr Raja Affendi elaborates.
Local study on probiotic benefits
Malaysia has also begun to study the efficacy of probiotics locally, and last year, a year-long research was conducted by researchers at the PPUKM. The research team, led by Assoc Prof Dr Raja Affendi, has found positive results from local research subjects that the Lactobacillus acidophilus and Lactobacillus paracasei strains in cultured milk drinks has benefits their health.
The study discovered there is a positive influence on our immune system. Significant reductions of IL-6 and IL-8 in constipation-predominant irritable bowel syndrome subjects were recorded. The same trend was also seen in healthy subjects. The level for tumour necrosis factor (TNF)-alpha, another important circulating cytokine has also dropped. TNF-alpha is a type of chemical released in the blood, usually associated with many acute and chronic inflammatory conditions including many cancer patients. The study concluded that consuming cultured milk drinks containing the two bacteria strains for 30 days led to significant reduction levels in IL-6, IL-8, and TNF-alpha among research subjects.
At the same time, the study also found noticeable improvements in digestive health. Some of the evidence discovered includes:
- up to 33% reduction (between 5-15 hours) in intestinal transit time – the time taken for food to travel from mouth through the digestive tract and eliminated as stool
- 96% of respondents reported significant improvements in constipation symptoms
- 45% of respondents spent less time in toilet
- 36% of respondents experienced less straining
- 31% of respondents had softer stools
Healthy lifestyle
However, Assoc Prof Dr Raja Affendi was quick to caution against relying purely on probiotics for digestive health. His recommendation was to stick to the basics, namely eating a healthy diet, exercising regularly, getting sufficient sleep and managing our stress levels.
"A healthy lifestyle is gold standard if you truly want to minimise your risk of disease and to ensure that your health and wellbeing do not suffer," he advises.
- 1 Cem Gabay (Arthritis Res Ther. 2006): Interleukin-6 and chronic inflammation
- 2 Akemi Imaoka, Tatsuichiro Shima, Kimitoshi Kato, et al (World J Gastroenterol. 2008 Apr 28): Anti-inflammatory activity of probiotic Bifidobacterium: Enhancement of IL-10 production in peripheral blood mononuclear cells from ulcerative colitis patients and inhibition of IL-8 secretion in HT-29 cells
- 3 Hojsak I, Snovak N, Abdovic S, et al (Clinical Nutrition 29, 2010): Lactobacillus GG in the prevention of gastrointestinal and respiratory tract infections in children who attend day care centers: A randomized, double-blind, placebo-controlled trial
- 4 Davidson LE, Fiorino A, Snydman DR, et al (European Journal of Clinical Nutrition, April 2011): Lactobacillus GG as an Immune Adjuvant for Live Attenuated Influenza Vaccine in Healthy Adults: A Randomized Double Blind Placebo Controlled Trial
- 5 Haywood BA, Black KE, Baker D, et al (Journal of Sports Science & Medicine, July 2014): Probiotic supplementation reduces the duration and incidence of infections but not severity in elite rugby union players
