Here’s everything you need to know about zinc and why it’s my favourite protective mineral. Are you getting enough?
What is Zinc?
Zinc is an essential nutrient used in many body systems and is integral for optimal human health. Zinc is the second most prevalent trace mineral in all living organisms and is involved in various aspects of life on earth. The human body can’t produce zinc (hence why we call it essential), and it cannot be stored for later use.
Therefore, zinc must be obtained through the diet.
Zinc is either part of a chemical reaction (catalyst), provides structure to proteins or it helps regulate a metabolic system. Incredibly, over 50 enzymes in the body depend on zinc for their proper function. What’s more, as much as 85% of systemic zinc is found in bones and muscle tissue.
How Much Zinc Do I Need?
Different stages in life will depend on your individual zinc requirements. Stages of rapid growth, such as during childhood and pregnancy will naturally increase zinc demands. Also, dietary zinc should be increased during periods of stress and acute illness to help fight infections and support your immunity.
Generally, the recommended dietary intake (RDI) for zinc is 11mg for men and 8 mg for adult women. A healthy diet consisting of vibrant plants, nuts, seeds, meat and seafood will ensure your zinc levels remain replete and your body will be working well.
Another thing to remember is that zinc levels detected in the blood are not indicative of your active zinc levels. Plasma zinc is only 1% of the total in the body. Zinc can’t be stored so your body will use it as it needs it. So what foods contain zinc?
Food Sources of Zinc
- Meat and seafood
- Nuts and seeds (sunflower seeds, chickpeas, cashews, pecans, almonds)
- Beans & Legumes
- Cheese & milk
- Foods fortified with synthetic zinc - commercial baked goods and cereals
Fun fact: 6 fresh oysters contain around 30-50mg of natural zinc.
Zinc Status & Vegetarianism
Generally speaking, zinc absorption will be more efficient in people consuming a diet with animal protein. This is because zinc binds to proteins during intestinal absorption, and animal proteins are more easily assimilated in the body compared to plant-based proteins. There’s a possibility, even theoretically, that plant-based or vegan diets may lead to zinc deficiency as a result of this phenomenon. Therefore, zinc status will certainly be something to monitor for vegetarians and vegans alike.
Zinc Deficiency: Signs & Symptoms
Zinc deficiency can manifest in various ways. Minor symptoms are usually common, and relate to what’s happening in your body day to day. Severe or chronic zinc deficiency can be harmful to your health, and often result from more serious or chronic health conditions.
Some common causes of zinc deficiency include:
- Acute respiratory illness
- Tissue trauma
- Chronic skin conditions
- Systemic inflammation
- Irritable bowel disease
- Digestive issues
Signs and symptoms of zinc deficiency Include:
- Unexplained weight loss
- Lack of appetite
- Recurrent infections (chest, colds, skin)
- Hair loss
- Skin rashes
- Macular problems or eyesight changes
- Changes in taste or smell
- Low libido and impotence
Why is Zinc So Important?
Zinc is critical for a range of health issues. These include:
- Wound healing
- Immune function
- Testosterone production
- Thyroid function
- Metalloenzyme function
- Gastric acid production
- Viral infections
- Macular degeneration & vision
- Reduces risk of pneumonia
- Reduces acne
- Supports growth and development
Zinc: The Immune System’s Weaponry
Here’s an example of how COOL the body is, when it comes to nutrients such as zinc. Our innate and adaptive immune systems are highly dependent on adequate zinc intake. In fact, when the body faces an invading microbe, a sophisticated mechanism of the immune system involves ‘hiding’ any free zinc that’s circulating in the body. This is because pathogens can use zinc to replicate and invade body tissue, causing infection. Another amazing defence mechanism is where immune cells (macrophages) engulf pathogenic material and ‘intoxicate’ these cells with excess zinc, thereby killing bacteria and preventing infection.
Pretty awesome, right? This is where we can appreciate that having replete zinc levels truly bolsters your immune cells and improves your body’s capacity to fight infectious agents. Some research even suggests zinc can reduce the duration of cold and flu symptoms by more than 30%.
Zinc & Respiratory Health
In recent times, the role of our immune system with particular focus on viral respiratory infections has received plenty of attention. Zinc protects respiratory epithelium from damage. Zinc has also been shown to possess direct antiviral effects and can ‘ameliorate SARS-CoV-2-induced lung injury’. This has been documented in several scientific papers over the last couple of years, where various protective mechanisms of zinc are described. An example of this is where zinc appears to impair SARS-CoV-2 infiltration by inhibiting the coronavirus spike protein’s ability to bind to angiotensin-converting enzyme receptors.
A 2020 article published in the International Journal of Molecular Medicine gave further praise to the role of zinc. Here, zinc proved to be a beneficial adjuvant therapy in COVID-19, alongside some conventional treatments. Zinc works to reduce respiratory inflammation and minimises the risk of an ensuing ‘cytokine storm’, often associated with further lung damage. Zinc also improves mucous clearance in the lungs and prevents ‘ventilator-induced lung injury’. Further evidence suggests that zinc enhances the activity of conjunctive treatments for COVID-19, including the use of Hydroxychloroquine.
Zinc Improves Diabetes Outcomes
One randomised controlled trial showed that zinc sulphate supplementation (30mg per day) for 6 months improved fasting blood glucose levels and augmented insulin sensitivity in prediabetic patients. These and other measures of glycaemic control were observed in many other studies, which involved moderate levels of zinc supplementation.
A 2019 systematic review including 1700 participants revealed that zinc-supplemented people had a statistically significant reduction in fasting blood sugar levels, insulin and inflammation. These findings further endorse zinc as a beneficial nutrient in the prevention or management of diabetes symptoms.
Zinc & Hormones
In the body, hormones are proteins which help signal growth and development. Zinc is essential for several different hormonal processes. Many diseases affecting hormones are associated with zinc deficiency. The impact of zinc status on insulin function was mentioned above. Zinc also affects growth hormone, which is responsible for bone, muscle and tissue growth during childhood and particularly adolescence. It’s also involved in thyroid hormone activation. Zinc is also critical for the conversion of testosterone from it’s precursor hormone DHT.
Zinc and The Nervous System
A finding published in Neuroscience Letters journal in 2019 reported on the importance of zinc with regard to neurodevelopment and nerve conduction. Zinc plays a critical role in the function of white matter in the brain, which is relevant to conditions such as stroke, multiple sclerosis and traumatic brain injury.
Zinc & Skin Health
Skin cells and underlying tissue are constantly regenerating. Therefore a high demand for nutrients via the diet like vitamin C and zinc are required for healthy ageing and maintaining skin barrier integrity. Zinc is also a mineral cofactor for collagen production in the skin. Topical zinc supplementation has also been shown to assist in wound healing and reduce inflammation, according to some research.
Should I take zinc supplements?
Zinc supplements can be very beneficial to most people, however they should really be given under the supervision of a qualified health practitioner. If you suffer from digestive issues, such as low stomach acid or have food malabsorption issues, zinc supplements can assist. Similarly, zinc can help in the instances of acute respiratory illnesses, like a head cold.
The correct dosage will depend on many factors. Your age, life stage and particular health condition will all play a role in how much supplemental zinc you should take. In most cases, 25-30mg is an ideal therapeutic range for addressing zinc deficiency.
Just remember that zinc supplements can interact with some prescription medications, including penicillamine, thiazide diuretics and some antibiotics. If you’re taking zinc, always consult a medical professional to double check.
Is it possible to have too much zinc?
Supplementing higher than 50mg of elemental zinc can cause stomach irritation, nausea and headaches. Levels exceeding 150 mg can interfere with the absorption of other minerals, like copper, calcium and iron.
Interestingly, this nutrient interaction seems to mostly be the case with elemental or synthetic zinc, from supplement intake. Rarely does this occur if you ingest high amounts of zinc naturally from foods. If you were to eat half a dozen oysters, for example, the body absorbs everything as it should, because of the synergistic nutrients and without cause for mineral competition.
Slow Cooked Lamb & Chickpea Curry
- 300g diced lamb
- 2 tablespoons olive oil
- 1 yellow onion, small diced
- 4 cloves of garlic
- 1 inch of ginger, peeled and finely chopped
- 2 cans whole peeled tomatoes
- 2 cans chickpeas (reserving ½ a cup of the chickpea brine)
- 2 teaspoons garam masala
- 2 teaspoons ground coriander
- ½ teaspoon ground turmeric
- ¼ tsp cayenne or chilli flakes (optional)
- 1 cup of coriander (stems chopped, leaves for garnish)
- Juice from ¼ of a lemon
- Salt and pepper
- In a pot over medium heat, add olive oil and seal the diced lamb until just brown. Remove and transfer to a slow cooker.
- Cook onions in the pot until golden, stirring often. Add a splash of water if they begin to burn.
- Add the garlic, ginger, and the spices. Cook for 1-2 min, stirring often, until aromatic. Add a dash of water to deglaze the pan, then transfer the onion and ginger mix to the slow cooker, covering the lamb.
- To the slow cooker - add canned tomatoes, chickpeas, coriander stems and reserved chickpea water.
- Season with salt and pepper and stir to combine.
- Cover and cook for 4-6 hours, or until fragrant and when the lamb is soft and cooked.
- To serve, squeeze over fresh lemon juice. Add naan bread or basmati rice and plain yoghurt.
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