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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.
Sweet potatoes, bean sprouts and yoghurt are good sources, too. Food processing can remove much of the zinc present in foods, however, especially grains, so following a wholefood diet will help to improve your intakes.
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 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.
As a result, sucking zinc acetate lozenges significantly reduces symptoms of viral infections such as the common cold.
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
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.
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.
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
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.
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.
The EU recommended intake (NRV or Nutrient Reference Value) for zinc is 10 mg per day.
The National Diet and Nutrition Surveys show that average intakes are less than this, however, with women aged 19 to 65 years only obtaining around 7.5mg from their diet, for example.6
Excess zinc can cause nausea. The suggested upper safe level for long-term use from supplements is 25mg per day. Higher amounts can be used short-term (e.g. lozenges for treating a sore throat) but stop if nausea develops.
Dr Sarah Brewer is Healthspan's Medical Director and holds degrees in Natural Sciences, Surgery and Medicine from the University of Cambridge. Having worked as a GP and hospital doctor, Dr Sarah now holds an MSc in Nutritional Medicine from the University of Surrey and specialises in nutrition. She is also an award-winning writer and author.
Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.