Introduction
Zinc is an essential trace mineral which plays a necessary role in many physiological functions within the body. It is required for immune system support, wound healing, DNA synthesis, and cell division. Zinc also contributes to the proper functioning of over 300 enzymes, influencing processes such as protein synthesis and hormone regulation. Maintaining adequate zinc levels is necessary for maintaining a healthy sense of taste and smell, as well as supporting normal growth and development during pregnancy, childhood, and adolescence.
As with all micronutrients, maintaining optimal intakes through diet and supplementation where necessary is absolutely essential. Deficiency in any nutrient will be of detriment to health, performance and more. Deficiency in zinc can lead to a range of health issues, including weakened immune response, delayed wound healing, hair loss, loss of appetite, and impaired growth in children. Chronic zinc deficiency may result in more severe conditions, such as impaired cognitive function and increased susceptibility to infections.
This article will present the vast body of research around zinc. It will begin by exploring the data on zinc deficiency, and the potential issues that this may cause. It will then present the research surrounding the impact that zinc intake has on health, immune function, inflammation, mental state, testosterone production, athletic performance and sleep. It will then present some dietary foods which are high in zinc to help you increase your daily intake of the mineral, as well as some things to consider when looking at zinc supplementation.
Global Deficiency Data of Zinc
A study published in 2012 investigated the global prevalence of zinc deficiency . The research found that approximately 17.3% of the global population has potential zinc deficiency, with higher rates observed in regions such as South Asia and Sub-Saharan Africa, where prevalence exceeds 30% (Wessells & Brown, 2012).
The study discusses a number of factors that may contribute to zinc deficiency, including dietary intake. Many populations, especially those in low income countries, have been found to be heavily on plant based diets which are lower in bioavailable zinc. These diets often include high amounts of phytates, compounds found in grains and legumes, which inhibit zinc absorption. Animal based foods, which are richer in bioavailable zinc, can often be less accessible or affordable for many people in developing regions. Malnutrition and inadequate overall dietary intake can lead to zinc deficiency, as insufficient consumption of essential nutrients impairs zinc absorption and utilisation. Additionally, infections and chronic illnesses can increase the body's zinc requirements (Wessells & Brown, 2012).
Hussain et al., (2022) have examined the potential health effects of zinc deficiency. They reported that zinc deficiency may weaken the immune system and may also impair cognitive function. Furthermore, zinc deficiency is linked with an increase in oxidative stress and inflammation, which may contribute to higher risks of chronic diseases such as cardiovascular conditions and diabetes. Additionally, they note that adequate zinc intake for children is key for growth and development.
The Effects of Zinc on the Body
The Research of Zinc’s Impact on Health
There is an extensive body of research which has investigated the health impacts of zinc. Zinc supplementation to correct deficiencies have been shown to improve immune function by increasing the activity of T-cells and natural killer cells, leading to a reduction in the incidence of lower respiratory infections. It is also generally supported in the article that adequate zinc intake maintains the body's antioxidant defence, potentially reducing oxidative stress, in addition to maintaining normal cognitive function (Li et al., 2022).
Another meta-analysis looked at 13 observational studies of 18,073 total participants, specifically reviewing the literature on the role of zinc in metabolic health. Zinc supplementation has been shown in several studies to improve insulin sensitivity in metabolic syndrome subjects. In the same subjects, it was found to help lower total cholesterol and LDL, whilst increasing HDL cholesterol (Ding et al., 2022).
Similarly, another meta analysis Jafarnejad et al., (2019) confirmed that zinc supplementation may improve glycemic control, reducing fasting blood glucose levels. This meta-analysis also supported that adequate zinc intake may positively influence lipid profiles.
Zinc’s Impact on Immune Function
A meta analysis by Jafari et al. (2022) reviewed data from 1995 study participants, highlighting the role of zinc in immune function. The review found that zinc supplementation in zinc deficient individuals helped the production and activity of immune cells, leading to a marked increase in the proliferation of T-cells and natural killer cell activity. Additionally, zinc was shown to potentially reduce the duration and severity of infections, with a decrease in the incidence of colds and a reduction in the duration of cold symptoms.
Hemila (2017) carried out a study on zinc acetate lozenges for the treatment of common colds. The research suggested that zinc acetate lozenges might be an effective means of overcoming symptoms of the common cold. They found that zinc lozenges consumed at dosages of 75-100mg per day may reduce the duration of common cold symptoms by 33% and decrease the severity of symptoms by 20%. Additionally, regular zinc intake was shown to lower the incidence of colds by 28% .
The beneficial effects of zinc on immune function received a great deal of attention during the COVID-19 outbreak, with research supporting positive effects of supplementation on COVID-19 symptoms. Tabatabaeizadeh (2022) conducted a meta-analysis and reported that zinc supplementation to negate deficiency might reduce the duration of COVID-19 symptoms by 25% and decrease the severity of symptoms by 20%. Patients with adequate zinc levels experienced a 30% lower risk of developing severe complications compared to those with zinc deficiency.
Zinc’s Impact on Inflammation
Research has been carried out to measure the impact of zinc on inflammation and inflammatory markers. Zinc supplementation has been shown to reduce levels of C-reactive protein (CRP), an important inflammatory marker. It also decreases interleukin-6 (IL-6) levels, further indicating its anti-inflammatory effects (Mohammadi et al., 2021).
Another study which was published in 2022 looked at the impact of zinc on inflammatory bowel disease (IBD). 33% of the data correlated zinc deficiency with elevated CRP (Zupo et al., 2022).
Zinc’s Impact on Cognitive Function
Zinc has also been researched for its role in cognitive function and mental health. A meta-analysis published in 2022 evaluated the effects of zinc supplementation on depression. The study found that zinc supplementation reduced depressive symptoms by 28% compared to placebo (Yosaee et al., 2022).
Further research has supported this suggestion. Swardfager et al. (2013) carried out a meta-analysis with 1643 depressed subjects and 804 control subjects. They found a correlation showing that individuals with depression often have 14% lower zinc levels compared to those without depression.
Zinc’s Effects on Testosterone
Zinc plays an important role in modulating testosterone. A study published in 2023 found that zinc supplementation increased testosterone levels by 17% in men with marginal zinc deficiency. Additionally, athletes who were supplemented with zinc experienced a 10% increase in testosterone levels after intense physical activity (Te et al., 2023).
An earlier study published in 1996 explored the impact of zinc on testosterone and other anabolic hormones, including IGF-1 and growth hormone. The research found that zinc supplementation significantly increased testosterone levels by 26% in zinc-deficient men. For the same cohort, it also elevated IGF-1 levels by 15% and growth hormone levels by 9% (Prasad et al., 1996).
The Impact of Zinc on Athletic Performance
Research has also explored the relationship between zinc and athletic performance, Micheletti et al. (2001) looked at nutritional habits of endurance athletes. They found that these athletes’ dietary habits high in carbohydrates and lower in proteins and fats may lead to suboptimal zinc intake in 90% of athletes, which may lead to loss in body weight, latent fatigue and decreased endurance.
Ghazzawi et al. (2023) explored the relationship between various micronutrients, including zinc, and athletic performance. They further supported the previous study, explaining that deficient zinc levels reduced endurance and increased latent fatigue. They concluded that zinc supplementation may aid athletic performance by reducing blood viscosity, increasing oxygen delivery which would in turn improve aerobic endurance. They further add that participants in one double blind crossover study supplementing 135mg/day of zinc for 14 days showed higher dynamic isokinetic strength and angular speed.
Intense exercise is generally known to lead to significant zinc losses, with athletes losing approximately 9% of their daily zinc requirement through sweat. This loss can contribute to a higher risk of zinc deficiency, which may impact muscle function, immune response, and overall performance (DeRuisseau et al., 2002).
Zinc’s Impact on Sleep
The impact of zinc on sleep is something which has relatively recently been looked at. Past research has found links between zinc and the central nervous system. Whilst more research is required to determine the mechanisms by which zinc might support sleep, the following research presented does show a promising link.
A systematic review published in 2016 explored the relationship between micronutrient status and sleep patterns, with a focus on zinc. The review found an association between decreased zinc intake and very short sleep duration in a general adult population. They also found that in randomised control trials of infants, those supplemented with inc had longer total sleep duration than a placebo group (Xiaopeng et al., 2017).
Further reviews of research found that orally administered zinc does increase the amount of and the quality of sleep in both mice and humans. Whilst the researchers were unsure to confirm the mechanisms by which zinc works to aid sleep, they theorised that zinc acts on circadian regulators to help regulate sleep (Cherasse & Urade, 2017).
Dietary Sources of Zinc
The Recommended Dietary Allowance (RDA) for zinc varies by age and gender. Adult men require 11mg per day, while for adult women the RDA is 8mg per day. Pregnant and lactating women require higher amounts, at around 11mg per day, respectively. Children need between 2-11mg daily, depending on their age.
In terms of dietary zinc sources, animal-based foods are amongst the best sources of zinc, including red meat, poultry, and seafood, especially oysters, which are exceptionally high in zinc providing up to 32mg of zinc per 3-ounce serving. Other good sources include beef, with 7mg per 3-ounce serving, and pumpkin seeds, offering 2.2mg per ounce.
Vegan and vegetarian sources of zinc include legumes such as beans, lentils, and chickpeas, although their zinc is considered to be less bioavailable than that from animal-based sources, due to the presence of phytates. Nuts and seeds, particularly pumpkin seeds and cashews, offer a decent amount of zinc. Whole grains like quinoa and brown rice can also contribute to zinc intake.
Zinc Supplements
Bioavailability refers to how well and how quickly a nutrient or medication is absorbed and utilised by the body. Simply, it measures the extent and rate at which an active ingredient or nutrient becomes available in the bloodstream and is able to have an effect where it's needed. For example, if you consume a magnesium supplement, bioavailability would indicate how much of the magnesium is actually absorbed into your bloodstream and used by your body vs how much is excreted without being utilised.
Osko et al., (2023) looked at the bioaccessibility of zinc supplements; bioaccessibility being the fraction of compounds which are accessible for absorption. They reported that zinc bisglycinate had the highest bioaccessibility, with a 9.38% absorption rate. In contrast, zinc sulfate showed the lowest bioavailability, with only a 1.13% absorption rate.
Earlier research has further supported that zinc bisglycinate has a high bioavailability, with an absorption rate which exceeded the compared form, zinc gluconate (Gandia et al., 2007).
Conclusion
To conclude, zinc is a key micronutrient with many roles in the human body, including maintaining immune function, normal wound healing, and metabolic health. Ensuring adequate zinc intake through diet and potentially supported with supplements, especially in some regions which are prone to deficiencies. The extensive research presented in this article supports zinc’s benefits, however the research does also highlight that increasing zinc intake is likely to only benefit those who are already deficient, which is estimated at about 17.3% of the global population.
Whilst you're here, be sure to take a look at our Sleep Hydration Sachets, which contain 2mg of Zinc per serving as well as other sleep aid ingredients such as L-Tryptophan, Ashwagandha, L-Glycine, Magnesium, Valerian Root Extract, Vitamin B6 and L-Theanine. If you would like to sample our full range of electrolyte sachets, be sure to explore our variety pack of hydration sticks.
Frequently Asked Questions (FAQs)
What are the main functions of zinc in the body?
Zinc is required in the body for many functions, including supporting the immune system, aiding in wound healing, synthesising DNA, and cell division. It plays a role in over 300 enzymatic reactions which govern physiological processes such as protein synthesis and hormone level regulation.
What are the best dietary sources of zinc?
Some of the best food sources of zinc predominantly include animal based foods such as oysters, red meat, poultry and sea food. You can also get zinc from plant based sources such as legumes, nuts, seeds and whole grains, however the zinc from these sources is generally considered to be less bioavailable due to the presence of phytates in plants, which inhibit absorption of the mineral.
How much zinc do you need per day?
The RDA (Recommended Daily Allowance) for zinc varies by age and gender. Adult men usually need 11mg per day, whilst adult women need 8mg per day. Children’s needs range from 2 to 11mg, depending on their age.
References
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