Leading-edge natural solutions…   always inspired by nature
2020 November

The role of Natural Killer (NK) cells in the severity of COVID-19

18th November 2020

Recent research reveals that Natural Killer (NK) cells may be at the centre of exciting new discoveries, which may reveal their role in determining the severity of SARS-CoV-2 (which causes COVID-19).

Our immune system plays a key role in protecting us from a wide variety of diseases, a role that is even more important during our current concerns about viral infections.

Our level of immunity, or how active our immune system is, is intrinsically linked to our diet (the quality, diversity and quantity of nutrients); our lifestyle (how physically active or sedentary we are); and our levels of toxicity (the number of toxic substances circulating in our body or stored in our fatty tissue). It is well known that those with a more sluggish immune system are more prone to succumbing to disease and in the time taken to recover from the disease. This is because our defences are weaker and our repair mechanisms are compromised.


Mediation of the Immune System

The immune system is not only our defence against the environment, it is also essential to maintain the integrity and function of the body. It also provides intelligence in the day-to-day housekeeping that is essential for us to remain alive.

Our primary immune response is mediated by lymphocytes (white blood cells), macrophages, mast cells, hormones and other messengers circulating in the blood and lymphatic systems.

NK cells are a type of lymphocyte, those white blood cells that are part of the innate immune system (they do not have a memory of infection but rather act on pure instinct at the moment). This instinctive branch of our immune reaction is the first line of defence against the environment and foreign invaders (like viruses, bacteria, parasites and toxins), including the severe acute respiratory syndrome (SARS), as well as tumour cells. NK cells are the most aggressive of our immune system’s soldiers. The motto of these microscopic Caped Crusaders is “seek-and-destroy.”

NK cells are pre-programmed to seek out and destroy infected and cancerous cells. However, they do not destroy indiscriminately. They are able to intelligently scan cells that they come in contact with, much like scanning a barcode, and they will very specifically destroy only faulty or infected cells.

Research has shown that patients with compromised (or overburdened) immune systems, or those that have undergone immunosuppressive therapy (radiation and chemotherapy), have decreased NK cell activity. In fact, in patients with metastatic disease, the survival time directly correlates with the level of NK cell activity. This NK activity is also severely reduced in autoimmune disease and chronic fatigue syndrome.


BioBran is a functional food, a complex of arabinoxylan compounds and other short-chain polysaccharides derived from rice bran that has been broken down by a specific enzyme from shiitake mushrooms. These unique compounds possess powerful immune-enhancing qualities, strengthening or increasing the activity of weak immune systems. This makes BioBran a potent food supplement immunomodulator.

First developed by Daiwa Pharmaceutical in Japan in the 1990s, and now backed by two decades of research (much of it peer-reviewed), Biobran is now the supplement of choice for many practitioners and their patients for whom elevating the immune system is a primary concern.

Yasuo Ninomiya, the founder of Daiwa Pharmaceuticals, explains: “We believe that it is of the utmost importance to trust in nature, with which we must coexist. We believe that the body’s natural healing power provides the foundation necessary to correct physical imbalances.

BioBran is made from insoluble (indigestible) fibre which has then been broken down (or ‘pre-digested’) in a proprietary process to produce unique soluble compounds with low-molecular-weight, allowing for easy and rapid absorption where it can begin the process of strengthening the immune system.  

Research on BioBran has been heavily directed to identify and support its anti-tumour and antiviral capabilities; however, it has also been used by doctors to:

  • Improve glucose tolerance

  • Enhance pancreatic function

  • Enhance hepatic (liver) function

  • Reduce the adverse effects of chemotherapy 

  • Improve quality of life

  • Neutralise free-radical production.

BioBran and NK cells

Dr M. Ghoneum, an immunologist at the University of California, LA. has been one of the primary Biobran researchers and has spent many years investigating its immunomodulatory effect. He stated: “I studied for almost ten years what makes NK cells weak and the factors that suppress the immune system… We know that stress suppresses the immune system.”  Dr Ghoneum explains further: “I couldn’t believe the evidence of my own eyes when I first saw the effect of Biobran. Here was a substance that substantially affects immune function, notably the activity of natural killer cells… BioBran has very high safety levels, on par with foods consumed in an ordinary diet. It has no side effects.”

This remarkable effect of BioBran on NK cells is due to its ability to increase NK-cell activity (rather than numbers of NK cells). This makes them much more effective fighters. The actual process by which their activity is increased is not well-understood, but this stimulatory effect targets only those cells that are sluggish, not cells that are vibrant. This suggests that BioBran normalises NK cells activity.

BioBran and COVID-19

Because BioBran displays impressive immune defence activity, it may be a useful supplement to take during this time, to help natural recovery and reduction of free radical damage. Research also shows that BioBran can support liver function, it is an ideal ally in supporting natural detoxification systems and elimination of toxins, which can greatly reduce the load in circulation and disencumber an already overwhelmed system.


BioBran 3 sachets of BioBran 1000 dispersed in a little water after a meal for 30 days

Then 1 sachet (or 4 tablets of BioBran 250 mg) per day for 2 weeks, or until support is required.

Biobran (powder sachets and 250mg tablets) is suitable for vegetarians and vegans. However, the low-dose Biobran Plus contains shellac and so is not suitable for vegans. This product is also  GMO-free. Talk to your doctor before taking BioBran and do not exceed the recommended dose.

For research and references, please email nutri@healthy.co.uk 


Maucourant, C. et al. (2020). Natural Killer Cell immunotypes related to COVID-19 disease severity. Science Immunology. 5, eabd6832. 

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