It is commonly known that zinc boosts the immune defense, although there has been some uncertainty about how. A team of scientists from Fred Hutchinson Cancer Research Center in the United States therefore decided to look closer at the subject and they found that zinc is important for T cell activity and for the thymus that produces the T cells. The scientists say that this new insight may be useful for the development of new therapies for patients with compromised immune systems. Apparently, zinc deficiencies are rather widespread and this increases the risk of infections where T cells play a key role in supporting the immune function.
Zinc is an essential trace element that is needed by all cells. It is involved in over 300 different enzyme processes. Furthermore, zinc-containing proteins code for around 10 percent of our genes that help cells in our immune defense and other tissues carry out their designated tasks. If we get an infection, our blood levels of zinc plummet because the white blood cells of the immune system suddenly need large amounts of zinc. Our innate immune defense is able to handle most infections without us noticing. If it needs reinforcement, the adaptive immune defense is activated. This immune system is characterized by directing targeted attacks at the enemy and establishing immunity. T cells play a key role in that they are able to divide explosively in order to attack germs and abnormal cells. T cells are also able to activate B cells that produce antibodies. However, it is the T cells that establish the best immunity against virus. All the white blood cells are produced in our bone marrow, and T cells are matured in the thymus.
Still, scientists have not quite been able to figure out how zinc affects the immune defense, so a team of researchers from Fred Hutchinson Cancer Research Center in the United States wanted to look closer at this.
Zinc’s importance for the thymus, T cells, and swift immune response
The scientists carried out their study on mice by feeding them diets with and without zinc. The zinc-deficient diets caused the mice’s thymus to shrink and produce substantially fewer matured T cells, even after three weeks. In other words, T cells are unable to mature or function normally without the presence of zinc.
The researchers also observed that mice that were zinc-deficient and had been given immunosuppressive therapy had an impaired ability to restore a normal T cell count. The therapy used on the mice was similar to the treatment that is given to patients prior to receiving a blood stem cell transplant. Needless to say, this treatment affects the patient’s thymus.
The researchers also found that zinc supplementation of zinc-deficient mice was able to speed up the process by helping the thymus and the T cells recover faster than normally, which is vital for an effective immune response. They saw a similar positive result of giving zinc supplements to mice that had been treated with the immunosuppressive drugs.
It remains unclear how exactly zinc worked so the team of scientists decided to take a closer look at the underlying mechanisms. They found that zinc supplementation raised zinc levels around the cells that initiate the regeneration of the thymus. Gradually, as the T cells mature and develop in the thymus, they accumulate zinc. When they finally attack germs and abnormal cells, they use generous amounts of zinc to conduct their warfare.
The scientists also found that the cells use a molecule called GPR39 to register changes in the surrounding zinc levels. The researchers even found that a compound that stimulates GPR39 is also able to speed up the regeneration of the thymus.
Their plan is to continue studying if supplementation with zinc or GPR39-stimulating compounds can be used in therapies for people with acute thymus damage or impaired immunity. Also, the scientists mention that the thymus shrinks as a natural part of ageing and that the new therapies may have the potential to delay this chronic degeneration of the thymus, thereby boosting the immune defense.
The study is published in the journal Blood and supports earlier studies that show how zinc supplements help the immune defense fight colds by shortening their duration and reducing the symptoms.
Zinc is also a powerful antioxidant that protects cells and tissues against oxidative stress caused by harmful free radicals. Ageing, chemotherapy, and radiation therapy are also causes of oxidative stress that can damage the thymus and other tissues.
Zinc sources and deficiency causes
Zinc is found in shellfish, fish, meat, dairy products, nuts, kernels, and beans. Zinc from animal sources has better absorption. Clinical zinc deficiency is rare in our part of the world, whereas subclinical zinc deficiency is widespread. Zinc deficiency and poor utilization of the nutrient can be a result of unhealthy eating habits, lack of animal protein, ageing, alcohol, diabetes, and kidney diseases. Diuretics, ACE inhibitors, antacids, corticosteroids, antibiotics, and birth control pills also increase the risk of a zinc deficiency.
Zinc requirements, supplementation, and safe upper intake level
The recommended daily zinc intake is 10 mg. It is best to get your zinc from the diet. If you choose to supplement, beware that organic zinc sources like zinc gluconate and zinc acetate have better absorption and are easier for the body to utilize.
The European Food Safety Authority (EFSA) has established a safe upper intake level for zinc of 25 mg for adults and pregnant women. It is harmless to ingest even greater quantities of zinc from oysters or supplements if it is for a limited period of time.
Zinc content in mg per 100 grams of food
Raw oysters 84
Kernels and seeds 3-5
Oats and beans 3
Rye bread and potato 1
Lorenzo Lovin et al. Activation of the Zinc-sensing receptor GPR39 promotes T cell reconstitution after hematopoietic cell transplant in mice. Blood, 2022
Fred Hutchinson Cancer Research Center. Burst of accumulated zinc shows how the mineral boosts immune function, suggesting ways to improve health
ScienceDaily March 31, 2022
Nikki Hancocks. Diet and supplements: Swiss panel publishes COVID-19 recommendations. 2020
Luke Maxfield, Jonathan S. Crane. Zinc Deficiency. NCBI March 18, 2019
University of Helsinki. Zink acetate lozenges may increase the recovery rate from the common cold by three-fold. ScienceDaily May 11, 2017
Zink for Colds, Rashes and the Immune system. WebMD. 2017
Frida - Parametre (fooddata.dk)