What Are Natural Killer Cells?

Natural Killer (NK) cells are part of your immune arsenal and help protect you from bacteria, viruses and cancer! NK cells are a type of lymphocyte which are a type of white blood cell. They are unique amongst our many white blood cells and work in tandem with T cells to attack and destroy pathogenic invaders and cancer cells.

NK cells roam the body looking for the bad guys and when they find them they have two very potent weapons. The first is a substance called interferon, which actually prevents viruses from replicating. The second type of weapon at their disposal are poisonous chemicals such as nitric oxide which destroys the internal machinery of any invading cells or organisms.

NK cells also produce cytokines which are an immune system communicator which allow NK cells to help regulate other cells of the immune system. It is an incredibly clever and fine tuned system that helps us recover from illnesses of all types.

NK cell activity declines with age and also when you are subjected to stress but the good news is you can boost NK cell, and therefore your immune response, through some very simple and inexpensive ways which we will explore in detail in this article.

The first way is through the hormone melatonin, which is discussed in detail in one of ourĀ previous blog posts. It appears that as we age and our melatonin levels decline so does our NK cell activity. This is believed to be because the thymus gland shrinks as we age and a great number of NK cells are produced, along with other types of T cells, in the thymus. Melatonin appears to maintain the size of the thymus which means more NK cells are produced in order to fight off disease and infections. The key takeaway is to get more quality deep sleep (which improves melatonin production naturally) or take an oral melatonin supplement to augment the amounts produced naturally in your body.

Exercise is a great way to boost NK cell activity along with boosting the whole immune system in general. While too much exercise, like that done by marathon runners, can suppress the immune system, the correct type and intensity of exercise can stimulate NK cell production. Exercise helps the immune system in a number of ways. The first one being the contraction of muscles aid in moving lymph around the body. Unlike the circulatory system which has the heart in order to move blood around the body the lymphatic system doesn’t have an equivalent to the heart.

Cortico-steroid hormones, often produced by stress, can lead to shrinking of the thymus gland which is a power house of the immune system. Vigorous exercise helps burn off these cortico-steroids helping maintain the strength of your immune army. According to Dr Michael Colgan:

“Trained athletes in good health have a higher number of NK cells, and a higher level of NK cell activity then sedentary folk.”

Exercise that is vigorous but not exhausting, performed 3-4 times a week will ensure that your NK cell army stay in peak condition.

Meditation has been shown to significantly increase the levels on NK cells in the blood. This deep form of relaxation has also been shown to raise melatonin levels which helps you sleep more easily.

Certain vitamins and minerals along with various herbs are all associated with boosting the NK cells and therefore your bodies ability to fight disease. Echinacea, which is a herb, has been shown to increase NK cell activity, which is probably why it is used as a common cold remedy along with Vitamin C and zinc. Garlic has also been shown in studies to improve NK cell response.