Zinc supplements could fight respiratory tract infection symptoms, suggests review

02 Nov 2021 --- A new study review suggests zinc supplementation may reduce the risk, duration and severity of respiratory illness, including coughing, congestion, colds, flu, pneumonia, SARS-CoV-2 infections and recovery from stroke. 

Indirect evidence has demonstrated a link between zinc supplementation and reduced virus risk, particularly in populations at risk of zinc deficiency, including people with chronic disease co-morbidities and older adults. 

Crucially, the study warns over 17% of the global population is estimated to be zinc-deficient and 20% of national diets contain insufficient zinc to meet minimum health requirements.

This review paper arrives amid scientific debate on zinc’s ability to reduce coronavirus symptoms. Some researchers have argued zinc, along with vitamins B3, C and D hold promise in reducing the risk or severity of COVID-19, while others flag zinc “fails to live up to its hype.”

Beyond immunity boosting
Published in Advances in Integrative Medicine, the review included 118 publications of 1,627 records. Four randomized clinical trials specific to SARS-CoV-2 are ongoing, with two investigating zinc for prevention and two for treatment. 

“The potential role of zinc as an adjuvant therapy for SARS-CoV-2 may be broader than just antiviral or immunological support,” the study authors write. 

“Zinc also plays a complex role in hemostatic modulation, acting as an effector of coagulation, anticoagulation and fibrinolysis. Zinc is also essential for neurological function.”

The global COVID-19 pandemic has prompted an urgent search for interventions to prevent and treat SARS-CoV-2.Unclear on dosage
While these study findings are “promising,” the effectiveness of zinc in preventing or treating SARS-CoV-2 infections is “yet to be systematically evaluated.” 

Most consumers are familiar with zinc supplements in the form of a lozenge, tablet, capsule, liquid or syrup. However, the study flags safety concerns associated with high doses or prolonged intake of zinc include anosmia (loss of smell) and copper deficiency.

Zinc gaining ground
Critically, zinc deficiency results in the impaired formation, activation and maturation of lymphocytes, disturbs the intercellular communication via cytokines and weakens the innate host defense. 

Consequently, zinc rose to the top of consumers’ immune health strategies, as evidenced by increased Google searches for the keywords.

A survey from this March revealed 41% of US consumers believe the ingredient supports immunity.

Direct evidence to determine if zinc is effective for either prevention or treatment of SARS-CoV-2 is pending.Zinc was also among the fastest-growing ingredients for immune health between 2019 to 2020, which grew at a CAGR of 78%. Examples of industry innovation in this space include new research to improve crops’ zinc uptake and zinc-biofortified ingredient launches.

On the flip side
Although these findings appear promising, other research highlights zinc supplementation may not be as effective as consumers assess it to be.

In an analysis of 300,000 UK users of the ZOE COVID Symptom Study App, study researchers were “surprised” they did not observe an effect for zinc, vitamin C or garlic supplements. These findings were reproduced in another ZOE study four months later.

The researchers behind a controversial US study, which found zinc and vitamin C did not help patients with COVID-19, stood behind their findings despite backlash from The Council for Responsible Nutrition (CRN). At the time, NutritionInsight spoke with experts from both sides of the debate.

By Anni Schleicher