When we spoke to health professionals about the precautions they were taking in the time of coronavirus , zinc supplements came up time and time again; GP Dr Clare Bailey said "If I get infected I plan to take a moderate daily dose of zinc, which has been found to reduce cold viruses by 50 per cent," while registered nutritionist Rob Hobson said: "I have been taking zinc for months now so hopefully this will be helping to keep my immune system in tip-top shape."
Retailer Victoriahealth.com has reported a recent surge in sales of zinc along with other immune supplements vitamin C, astragalus , Better You Vitamin D Spray and a multi-greens powder called Life Drink by Terranova.
Earlier this month there was a stampede for zinc lozenges after a noted US pathologist James Robb (who described himself as "one of the first molecular virologists in the world to work on coronaviruses”) sent a coronavirus advice email intended for his friends and family but which went (fittingly) 'viral'.
"Stock up now with zinc lozenges. These lozenges have been proven to be effective in blocking coronavirus (and most other viruses) from multiplying in your throat and nasopharynx," he wrote. "Use as directed several times each day when you begin to feel ANY 'cold-like' symptoms beginning. It is best to lie down and let the lozenge dissolve in the back of your throat and nasopharynx." It caused a run on the US brand that he mentioned, and Robb since told the website snopes.com that he didn't intend to advertise any one product, While in his experience as a virologist and pathologist "zinc will inhibit the replication of many viruses, including coronaviruses," he said, he added that he had no direct evidence that it could inhibit COVID-19. He did expect it would be inhibited similarly but that inhibition was no guarantee against infection.
So what to think, is zinc a wise precaution? If a respected GP Dr Bailey plans to take it then it could be worth a shout. It's certainly a highly lauded supplement when it comes to the virus we know so well - the common cold - and which we've also yet to cure. Dr Bailey's husband Dr Michael Mosley rates it for its cold-curbing ability - it has impressive preventative potential, as seen from a study conducted by the University of Alberta that found that children who took 10 to 15mg of zinc daily, were less likely to miss school due to a cold.
Taking a zinc supplement can also decrease the length of a cold too, as seen in another study that found that zinc acetate lozenges reduced duration from seven days to four. “It is theorised that zinc lozenges may work because positively charged zinc is strongly antiviral and astringent,” explains Shabir Daya , pharmacist and co-founder of Victoria Health . “It seems to also protect our membranes from a variety of assaults too.” It's not just good for colds, it plays a role in fertility for men and women, in making one of the body's most powerful antioxidants called zinc/copper superoxide dismutase (SOD) as well as in brain health and skin healing.
"Zinc is necessary for the repair of our genetic material, for helping skin to heal, for growth and for over 300 enzyme systems, which control countless processes in the body including taste, smell and metabolism, " he adds."Zinc deficiencies can also lead to hair loss, skin lesions, diarrhoea and impaired vision. We cannot underestimate the many benefits of having adequate zinc in our bodies."
How can zinc fight a virus?
Zinc prevents viruses from attaching to cells in the nasal passage and therefore stops them from entering the body, nutritional therapist Christine Bailey told us before the coronavirus pandemic. What’s more, it plays an important role in immune function. "Zinc plays a crucial role in supporting optimal immune system function," added Shabir. "White blood cells which help to fight off infection depend upon zinc for their development and activation. A deficiency of zinc can result in diminished amounts of white blood cells and reduced ability to fight infection and heal wounds. This is precisely why zinc supplements are often recommended for fighting colds and flu.
How much zinc do I need?
Many of us are deficient in this mineral - approximately 20 per cent of the world's population, according to Shabir - and it’s something that Christine frequently sees in her clinic. Daily requirements are recommended at 7mg if you’re a woman, 9.5mg if you’re a man and sticking to these quotas has been linked to a stronger immune system and greater resiliency to illness.
What are the best foods to eat for zinc?
The best dietary sources in Christine’s experience include shellfish such as oysters, crabs, mussels, lobsters and clams, lean meats such as beef, pork, lamb and poultry like turkey and chicken, and also some fish like sardines, salmon and sole. If you’re vegetarian or vegan though, seek out your zinc in beans and pulses like chickpeas, lentils, black beans and kidney beans, as well as nuts and seeds such as pumpkin seeds, cashews, hemp seeds and tahini. Some can be found in certain grains such as oats, quinoa, brown rice and fortified breakfast cereals too.
Why take a zinc supplement?
While reaching the amounts recommended is achievable through diet, Christine highlights that you’d need to eat quite a lot of the foods highlighted in order to do so: 7mg per day roughly equates to seven tablespoons of tahini (that's a whole lot of calories) 100g - around one packet - of pumpkin seeds or four cupfuls of cooked chickpeas; one small cooked fillet steak, 125g canned crab, 200g roast turkey or five cupfuls of plain low-fat yoghurt.
While a ‘food first, supplements second’ approach is best, a zinc supplement can be useful in Christine's experience, for correcting a deficiency. It can also serve as a helping hand in getting you up to a higher immune health-boosting dose that can prevent the first signs of a cold developing into something worse.
What should you look for in a zinc supplement?
Zinc lozenges can be particularly effective when taken as soon as you feel a cold coming on (say if you have a scratchy throat, for example). The type of zinc compound that your supplement contains is key though. “Choose absorbable forms such as zinc citrate or zinc gluconate,” advises Christine. “Stay away from zinc oxide, which is poorly absorbed.”
How long should you take a zinc supplement for?
To prevent a cold from taking hold, taking a zinc supplement for the first two to three days of showing symptoms can be helpful. It’s most effective if taken within 24 hours, according to this study . It’s important to ensure that you aren’t taking it in conjunction with other zinc supplements though (say if you’re taking a multivitamin), to avoid going over safe limits. Also, consider how much zinc you're getting from your diet and that your intake of other immunity-boosting nutrients is taken into account too.
“If you’re taking a zinc supplement for colds and flu, it is for short-term use only and should be no more than 25mg,” Christine says. Taking more than the recommended daily amount of zinc for long periods of time may inhibit copper and iron absorption and cause nausea, diarrhoea, headaches and/or abdominal cramps.
The best zinc supplements for colds
Here are Christine’s and Shabir’s top picks. If you’re on prescription medication, consult your GP first as taking a zinc supplement can interfere with them.