Zinc nutrient guide: benefits, foods, deficiency and supplements

What does zinc do?

Zinc is an important mineral needed for over 300 body enzymes to work properly. It is involved in many different aspects of cell metabolism, including the way that genes are switched on in response to hormone triggers.

This makes it vital for normal growth, sexual maturity and fertility. Zinc also plays a central role in immunity and helps to protect against infections such as the common cold, as well as promoting normal wound healing.

Zinc foods

• Red meat
• Seafood (especially oysters)
• Liver
• Kidney
• Wholegrains
• Nuts
• Seeds (especially pumpkin seeds)
• Pulses (lentils, soy beans)
• Eggs

Sweet potatoes, bean sprouts and yoghurt are good sources, too. However, processing can remove much of the zinc naturally present in foods, especially grains, so following a wholefood diet will help to improve your intakes.

Zinc deficiency

Zinc supports a number of critical functions in the body, and as we can't store it, it's essential to have a regular intake.

It's important not to become deficient in zinc, as it has proven benefits for supporting bone health, reproductive health and cognitive function, as well as helping keep your eyes, hair, nails and skin healthy.

Zinc benefits

Immunity

• Contributes to the normal function of the immune system
• Has been shown to reduce the duration of symptoms of the common cold

Zinc is a popular remedy for sore throats and the common cold. Sucking zinc acetate lozenges appears to inhibit viral replication, and boosts the action of white blood cells in the throat to help reduce symptoms of the common cold and other viral infections.

In people with colds, zinc lozenges help to shorten the duration of nasal congestion by 37%, scratchy throat by 33%, hoarseness by 43% and cough by 46% when compared with placebo, as well as reducing the duration of muscle aching by 54%.¹

Start using zinc lozenges as soon as possible after a sore throat develops, and use them regularly throughout the day according to the manufacturer's instructions.

The results from 17 studies also found that children taking zinc tablets were 20% less likely to develop a lower respiratory tract infection such as pneumonia than those not taking them.²

Other research shows that zinc helps to block the replication of Herpes simplex viruses, which cause cold sores, by up to 90%.

Among 20 people with more than 6 episodes of recurrent herpes cold sores per year, taking zinc supplements more than halved the average rate of recurrences to 3 per year, and reduced the duration of each episode to an average of 5.7 days.³

Applying a zinc oxide cream can also help to shorten the duration of cold sores.⁴

Bones

• Contributes to the maintenance of normal bones
• Enhances the action of vitamin D, essential for bone repair

Zinc is needed for maintaining strong, healthy bones as it helps to regulate the synthesis of collagen protein needed to support bone minerals.

Zinc also enhances the actions of vitamin D, which is essential for calcium absorption and bone repair. Studies show that women with osteoporosis have blood and bone levels of zinc that are up to 30% lower than in women with healthy bones.

Hair, skin and nails

• Contributes to the maintenance of normal hair, skin and nails
• Can guard against white spots on nails

Zinc is important for collagen production and the growth and strength of healthy hair, skin and nails. Lack of zinc has been associated with scaly skin, thinning hair, hair loss and weak nails.

Zinc deficiency also increases the chance of developing white spots on nails, as it can affect the normal healing response to unnoticed minor trauma at the base of the nail, such as knocking a finger against a door frame as you walk through.

Fertility

• Contributes to normal fertility and reproduction
• Helps maintain normal testosterone levels

Zinc plays many roles in fertility and reproduction. It is needed to maintain normal testosterone levels, for example, and adolescents who are lacking in zinc can experience delayed puberty as a result.

Zinc helps to package genetic material within the head of healthy sperm. It is also vital for the release of enzymes on the head of sperm that allow them to penetrate an egg for fertilisation (acrosome reaction).⁵

Vision

• Contributes to the maintenance of normal vision
• Contributes to normal metabolism of vitamin A, essential for vision

Zinc is concentrated within the retina of the eye and is vital for normal vision. Zinc is also needed for the normal metabolism of vitamin A.

Within the eye, vitamin A is converted into a pigment, rhodopsin (visual purple) which absorbs light waves and stimulates nerve endings to relay sensory information to the brain, where it is interpreted to form images.

What else can zinc help?

As well as being important for normal cognitive function (thought processes), zinc is needed for cell division, DNA synthesis, the metabolism of proteins, carbohydrate and fats, and for maintaining the correct level of acidity in the body.

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How much zinc do I need per day?

The Australian Government states that for adults over the age of 19 years, the EAR for zinc is 12mg. The RDI is 14mg per day.⁶

Can I take too much zinc?

Excess zinc can cause nausea. According to the Australian Government's guidelines, the suggested upper safe level of zinc is 40mg per day.⁷ Higher amounts can be used short-term (e.g. lozenges for treating a sore throat), but stop if nausea develops.