Zinc is now widely understood to play critical roles in immune function, protein synthesis, wound healing, DNA synthesis, and cell division.
Deficiency of this essential nutrient can cause growth and cognitive defects, poor immune function, impaired wound healing, and a slew of other bad things. Fortunately, zinc is present in a variety of foods, especially animal products, such as meat, eggs, and milk. Lesser amounts can be found in plant-based foods.
Plant sources of zinc also contain phytates – naturally occurring compounds that can inhibit zinc absorption.
As a result, vegetarians and vegans might be at greater risk for developing zinc deficiency. But meat eaters who have poor gut function or are heavy drinkers might be at risk, too.
Zinc modulates many aspects of the immune system and is essential for proper immune function.
A growing body of evidence suggests that zinc is beneficial against pneumonia, HIV, acne, and even sepsis – a life-threatening inflammatory condition that can arise due to the body’s response to a bacterial or viral infection.
Serum zinc concentrations drop markedly during sepsis. One study showed that patients who died due to the complications associated with sepsis had zinc concentrations that were 60 percent lower than their baseline levels.
The decrease in serum levels of zinc observed in people with sepsis might be a result of nutritional immunity – a biological phenomenon wherein a host organism sequesters minerals such as zinc or iron in an effort to reduce a pathogen’s virulence.
During an infection, circulating levels of these minerals decrease rapidly and dramatically, starving the invading pathogens of essential nutrients and limiting disease progression and severity. Restoring zinc status during infection could render a potentially harmless dose of zinc into a toxic one.
Zinc – in the form of zinc lozenges – is perhaps best known for its role in reducing the incidence of the common cold.
A plethora of studies have investigated zinc’s effects on colds, with most of the studies finding that zinc reduced the duration of a cold by roughly 20 to 40 percent (with sufficient dose).
For example, one study found that people who took 80 to 92 milligrams of zinc per day during a cold episode recovered approximately three times faster compared to those who did not take zinc. On the fifth day of supplementation, nearly three-fourths of the patients who took zinc had recovered, compared to roughly one-fourth of those who did not take zinc.
The benefits of zinc on the brain are perhaps less known.
Zinc exerts a diverse range of effects in the brain throughout a person’s lifespan.
From influencing fetal brain development, to improving outcomes associated with traumatic brain injury, to improving a person’s response to antidepressants, zinc is a key player. Questions remain regarding zinc’s role in Alzheimer’s disease, with some studies demonstrating that zinc concentrations increase with Alzheimer’s disease, and others demonstrating the converse.
The mineral affects multiple other organs and systems, as well, and might be beneficial against diabetes and impaired lipid metabolism.
That’s because zinc is essential for healthy metabolic function.
Some research shows that zinc supplementation can improve glucose regulation in people with diabetes, reducing fasting blood glucose concentrations and improving HbA1c levels (a measure of long-term blood glucose control).
The effects of zinc on lipid metabolism are mixed, however.
Zinc supplementation might be effective in decreasing the risk of cardiovascular disease in unhealthy people by decreasing LDL and increasing HDL levels. But high-dose zinc supplementation in healthy people might reduce levels of HDL – the “good cholesterol” – which could increase a person’s risk for cardiovascular disease.
Zinc supplementation carries some risk for toxicity.
Moderate doses can cause some gastrointestinal discomfort, diarrhea, or nausea, but higher doses can cause acute vomiting. And long-term high dose zinc supplementation is associated with copper deficiency, so caution is advised when supplementing.
Zinc supplements are typically sold as water-soluble salts such as zinc gluconate, zinc sulfate, zinc acetate, zinc citrate, zinc oxide, or zinc picolinate.
Each of these supplemental forms contain different percentages of elemental zinc, with some having better bioavailability than others. In general, zinc gluconate and zinc sulfate appear to be better absorbed than the other forms.
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