[Dailypharm reporter Kang Hye-kyung] “Immunity” is the word that comes to mind when we think of conditions such as COVID-19, the common cold, influenza, and seasonal allergies.
The market is also being flooded with health functional foods emphasizing immunity, such as immune vitamins and immune probiotics. However, taking them without properly understanding one’s condition may do more harm than good, for example by leading to unnecessarily high doses.
Recently, interest has been growing in functional medicine, which focuses on restoring normal function through individualized diagnosis and assessment rather than taking a disease-centered approach. This is because understanding and demand are increasing for a patient-centered approach that comprehensively evaluates genetic, environmental, and lifestyle factors to identify the root causes of disease and establish personalized management plans.
Dr. Kim Dong-hwan, President of the Korean Society of Nutritional Medicine and a medical doctor at the HM Cellex Longévité Anti-Aging Center of Hyundai Aesthetic Surgery, also emphasizes preventive management before a condition reaches the disease stage. He explains that whether the same cold remains mild or progresses to pneumonia or another serious condition may depend on an individual’s immune status.
—How is immunity assessed in functional medicine?
Tests examine a wide range of research indicators related to immunity, including the gut microbiome, stress hormones, white blood cells, minerals, and fatigue levels. The core of functional medicine is to replenish deficient nutrients so that people can eat, sleep, and live well. In other words, it aims to boost and support “innate immune cells,” the first line of defense against invading external viruses or mutated cells such as cancer cells, so that they can perform their role effectively.
—There are many products said to support immunity. What are your thoughts?
Countless immune health functional foods and supplements are entering the market, yet the key to safely and reliably activating the body’s innate immunity is unexpectedly found in a traditional fermented food. It is potassium poly-γ-glutamate (PGA-K), a functional ingredient isolated, cultured, and purified from the sticky, string-like mucilage that stretches when cheonggukjang is lifted with a spoon.
PGA-K is a high-molecular-weight amino acid substance produced as traditional cheonggukjang bacteria (Bacillus subtilis) ferment soybean proteins, then isolated and purified using specialized technology. It is highly effective in stimulating and activating natural killer cells (Natural Killer Cells, NK cells).
It is also an individually approved functional ingredient whose functionality and safety have been recognized by the Ministry of Food and Drug Safety for its potential to “help enhance immune function.” No matter how many beneficial nutrients a person consumes, the overall immune system is rendered nearly ineffective if NK-cell activity is low, which is why this ingredient warrants particular attention.
—Is there supporting evidence, including clinical evidence?
The immune-enhancing effects of PGA-K have moved beyond the realm of folk remedies and have been scientifically validated through clinical trials and publications in internationally recognized journals. According to a human study conducted by a clinical research team at Seoul St. Mary’s Hospital, The Catholic University of Korea, adult men and women who consistently took PGA-K for eight weeks showed a remarkable 52.3% increase in NK-cell activity compared with a control group that did not take it. This indicates that the body’s internal defenses became more than 1.5 times stronger.
It was also confirmed that secretion of cytokines, including interferon gamma (IFN-γ)—a key substance through which immune cells communicate and regulate immune responses—was significantly promoted.
More recently, studies published in international journals including PLOS ONE have elucidated an immunomodulatory mechanism by which PGA-K induces the death of specific allergy-triggering cells, known as basophils, thereby contributing to antiallergic effects and improvements in atopic dermatitis.
This demonstrates its value in promoting so-called “immune balance,” calming an excessively activated immune system while strengthening a weakened one. In addition, it helps optimize the environment for the growth of beneficial gut bacteria, in the intestine where more than 70% of the body’s immune cells are concentrated. It also offers dual functionality by keeping calcium dissolved in the small intestine so that it does not precipitate and get excreted, thereby increasing calcium absorption in the body. Thus, gut health, bone health, and systemic immunity are closely interconnected through a single ingredient.
—Which is the more convenient way to take it: through food or health functional foods?
Cheonggukjang and natto are traditional foods that are generally beneficial to health, but it is difficult to obtain PGA-K, the immune-functional ingredient, from them in ordinary food form.
This is because even consuming natto or cheonggukjang as regular foods cannot be considered equivalent to consuming PGA-K, a functional compound produced through separate processes such as culturing and purification. Moreover, when traditionally prepared cheonggukjang is heated in dishes such as stew, some beneficial bacteria and heat-sensitive active ingredients may be lost, and there is also a risk of excessive sodium intake.
Therefore, to fully benefit from its effects in enhancing and maintaining immunity, using PGA-K extract in health functional food form—with the active ingredient safely isolated and purified from cheonggukjang at a high concentration—may be a much wiser and more efficient alternative than consuming natto or cheonggukjang as food.