Zinc’s role in the immune system and combating respiratory infections

Zinc holds several crucial roles in the immune system. A zinc deficiency therefore impairs the metabolism of white blood cells and weakens the capacity of the immune system, thereby increasing the risk of influenza, COVID-19, pneumonia, and other respiratory diseases. This was outlined in a review article published in the journal Immunometabolism.

Respiratory infections are a serious global burden. According to the Global Burden of Disease Study, more than half a billion people suffer from chronic respiratory diseases, and the WHO estimates that around 3 billion people are affected by influenza annually, including 3-5 million complicated and life-threatening cases. The COVID-19 pandemic has increased the need for better natural prevention.
Since the dawn of time, the immune system has been responsible for fighting viruses, bacteria, and other pathogens. The innate immune system, consisting of a range of proteins and white blood cells, plays a crucial role in immune signaling and inflammatory processes. It may also call on the acquired immune system, which is more specialized and capable of developing immunity.
When the innate immune system is activated, white blood cells produce a large number of free radicals that work like missile weapons by killing pathogens. In addition, protective antioxidants are needed to prevent oxidative stress where free radicals damage healthy cells.
The innate immune system, which acts as guardsmen on mucous membranes and street patrols in the bloodstream, handles most pathogens without any symptoms. If an infection takes hold, it usually takes about a week for the acquired immune system to be fully mobilized and to combat the pathogens.
If the immune system is severely weakened, there’s a risk that bacteria from the body’s natural flora in the throat can spread to the sinuses or lungs and cause complicated infections.
There is also a risk that the immune system may overreact with a cytokine storm and hyperinflammation, which can make infections such as influenza and COVID-19 potentially life-threatening due to leaky blood vessels and organ failure.
That is why it is so important for the immune system to function quickly, effectively, and without overreacting – something which, among other things, requires nutrients like zinc.

Zinc’s role in the innate and the acquired immune systems

The review article describes how zinc is vital for overall health. It serves as a cofactor in more than 300 enzymatic processes, supports the structural integrity of cells, and contributes to protein function. Zinc also plays a role in gene activation and expression via so-called “zinc fingers.”
With relation to the immune system and respiratory infections, zinc is involved in several functions, including:

• Development and maturation of innate immune cells such as neutrophils, macrophages (phagocytes), and NK cells
• Phagocytes' ability to engulf and destroy pathogens
• Development and maturation of acquired immune cells, including B cells that produce antibodies and T cells' ability to absorb blood sugar and initiate a proper immune response
• Maintenance of strong epithelial cells, including those lining the respiratory tract
• Antiviral activities that also prevent viruses from replicating in infected cells
• Antimicrobial activities
• Antifungal activities
• Reducing inappropriate inflammation, including hyperinflammation
• Supporting the function of the vitamin D receptor, which is crucial for both innate and acquired immune responses
• Being a component of the antioxidant enzyme SOD (superoxide dismutase), which protects against oxidative stress-related cell damage

The authors detail how zinc is involved in a wide array of complex metabolic processes within the immune system, and why the immune system performs poorly in the case of zinc deficiency.
They also cite several studies showing that zinc supplementation can improve immune function and help prevent or alleviate respiratory infections in cases of deficiency. In acute infections like the common cold, higher short-term doses of zinc have been shown to reduce the duration of illness.

Zinc sources, absorption, and common deficiencies

Good dietary sources of zinc include shellfish (especially oysters), fish, meat, eggs, dairy products, as well as nuts, seeds, and legumes. Zinc from animal sources is more easily absorbed.
Recent U.S. data suggests that most people get enough zinc from their diet, but certain groups, including older adults, vegetarians, and individuals with impaired nutrient absorption due to gut disorders or other causes, are at increased risk of becoming zinc deficient.
Elderly people are particularly vulnerable due to reduced appetite and imbalanced diets. It is estimated that most people older than 60 years of age only get about half the officially recommended amount of dietary zinc. Aging may also impair absorption and worsen the problem.
Moreover, vegetarians and vegans may be at risk since zinc is most readily absorbed from animal-based sources. Absorption can also be inhibited by oral contraceptives and vitamin B6 deficiency. Excess copper, especially from environmental sources, can deplete the body’s zinc reserves.
Since we are unable to store zinc, deficiencies can arise quickly and weaken the immune function.
The review article recommends zinc supplementation for those with an insufficient zinc intake or nutrient malabsorption.

Zinc requirements and supplementation

In Denmark, the daily recommended intake is 10 mg. In the case of deficiency, one should initially try to include more high-zinc foods in the diet.
The upper daily limit is 40 mg, but therapeutic doses of 50-75 mg daily can be taken short-term during an acute infection. Nonetheless, prolonged intake of high doses may reduce the body’s absorption of iron and copper.

References:

Jonathan H Yao et al. Impact of zinc on immunometabolism and its putative role on respiratory diseases. Immunometabolism. 2025

Ashton Amos, Mohammed S. Razzaque. Zinc and its role in vitamin D function. Current Research in Physiology. 2022

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