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Although required in minute amounts, hence the term ‘trace mineral’, zinc is vital for human health. This powerful antioxidant is found in every tissue in the body. As well as fighting destructive free radicals it helps to regulate our thyroid hormones (critical if you are trying to lose weight), supports our immune system and is essential for mental health. In fact it has now been well established that zinc deficiency is common in several psychiatric disorders including depression.
Underactive thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism) both result in zinc deficiencies and as zinc is required by the thyroid to convert T4 hormones into T3 hormones, when we are running low it can cause no end of problems. Obesity also often goes hand in hand with low zinc levels, so if you are carrying more than a few extra pounds you may need to top up. This is especially true if you enjoy a glass or two of wine or a few gin and tonics as alcohol further depletes zinc in the body.
The highest concentration of zinc is found in meat and seafood. Needless to say vegetarians and vegans are more likely to be deficient in zinc. The liver and onions, steak and kidney pie, and Cullen skink my grandparents ate were great sources of zinc and very different from the processed food we eat today. In fact studies now show our zinc intake has declined over the past 60 years and a report from Professor John H. Beattie, Head of Micronutrients Group at the Rowett Institute of Nutrition at the University of Aberdeen states we are consuming less zinc today than we were during rationing in WWII!
Like vitamin C our bodies can’t produce zinc so we need to get it from food or by taking supplements. Foods rich in zinc include: oysters with a whopping 74mg per serving, crab, lobster, beef, lamb, beans, whole grains and nuts. Unfortunately zinc levels in modern wheat have plummeted in recent decades – with 30% less than wheat grown in 1968. Dark chicken meat also contains zinc but today we often prefer chicken breasts, goujons, and nuggets.
The RDA for zinc varies from country to country but on average it is around 11mg. The upper safe limit is 25mg and studies show taking 25mg of zinc daily improves the immune system and may minimise the symptoms of everyday colds and flu.
Over two billion people suffer from mild zinc deficiencies and symptoms include lack of concentration and poor neurological function, weak immunity (always catching colds and infections), diarrhoea, allergies (runny nose, sneezing, hives etc.), poor night vision, acne, skin rashes or breakouts. If you are unsure about your zinc levels or recognise any of the symptoms then it’s best to ask your GP to run a test. If you are low then simply incorporate more zinc-rich foods into your diet or take a supplement.