What Is Zinc?

CoachMel Healthy Eating 6 Comments

Zinc is a trace mineral, which it has a number of important functions within the body.

Some of these functions include helping to make new cells and enzymes, processing carbohydrates, fats and proteins, and helping with wound healing.

Daily intake of zinc is required to maintain healthy levels, because the body does not have a zinc storage system.

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There is also some suggestion that zinc can help to improve symptoms of the common cold. However, this is inconclusive.

A 2007 review of the effect of zinc lozenges, nasal sprays, and nasal gels, on the common cold, looked at 14 randomized, placebo-controlled studies. Seven of those studies (5 using zinc lozenges, 2 using a nasal gel) found that the zinc treatment had a beneficial effect. However, seven (5 using zinc lozenges, 1 using a nasal spray, and 1 using lozenges and a nasal spray) found no beneficial effort at all.

One review, however, did conclude that zinc can reduce the duration and severity of cold symptoms.

Despite the inconclusiveness of this research, maintaining a healthy zinc status within the body could certainly be helpful, if you find yourself prone to common cold symptoms.

Symptoms of zinc deficiency

A mild zinc deficiency may cause no obvious symptoms, however severe deficiency may show some of the following:

  • Weight loss
  • Loss of appetite
  • Lethargy
  • Diarrhoea
  • Impaired immune function and being prone to infections
  • Impaired wound healing
  • Growth retardation
  • Hair loss, inflammation of the skin (dermatitis), skin infection around the nails (paronychia)
  • Impaired nerve conduction and nerve damage
  • Macular degeneration, night blindness
  • Impaired taste and smell
  • Iron deficiency anaemia

Those susceptible to zinc deficiency include, strict vegetarians, people with bowel inflammation diseases, those with long-term diarrhea, people who are anorexic, people with HIV and AIDS, and pregnant or breastfeeding women, who eat a poor diet.

Most people should, however, be able to get enough zinc for their bodily needs, by eating a varied and healthy diet.

Dietary Reference Intakes For Zinc

The Institute of Medicine, at the National Academy of Sciences, have set the Recommended Dietary Allowances for zinc, these are:

Zinc RDA For Men

0-6 months: 2 mg
7-12 months: 3 mg
1-3 years: 3 mg
4-8 years: 5 mg
9-13 years: 8 mg
14-18 years: 11 mg
19+ years: 11 mg

Zinc RDA For Women

0-6 months: 2 mg
7-12 months: 3 mg
1-3 years: 3 mg
4-8 years: 5 mg
9-13 years: 8 mg
14-18 years: 9 mg (pregnancy 12 mg, breastfeeding 13 mg)
19+ years: 8 mg (pregnancy 11 mg, breastfeeding 12 mg)

Which Foods Contain Zinc?

This important mineral is available in a wide variety of foods. Here are some of them:

  • Fish — oysters, lobster, crab, canned sardines, white fish
  • Meats — red meats, like beef shank or stewing steak, calf’s liver, pork, lamb, also chicken and turkey
  • Nuts and seeds — sesame seeds, pumpkin seeds, pecans, Brazil nuts, peanuts, cashews, hazelnuts
  • Dairy and eggs — milk, yogurt, cheddar cheese, eggs
  • Legumes — lima beans, baked beans, soybeans
  • Fruits and vegetables — mushrooms, spinach, sea vegetables, green peas, summer squash, asparagus, collard greens, broccoli, turnip, ginger root, garlic, dried fruits
  • Grains — wholewheat, rye, oats, buckwheat, wholewheat bread and pasta, fortified breakfast cereals

Zinc Interactions

One of the main problems with zinc is that its absorption is decreased by drinking tea or coffee with your meals, or eating certain vegetables and wholegrains, which contain phytic acid (found in fiber). Zinc links up with this phytic acid to form zinc-phytate, and this is not absorbed by the body.

This does not mean that you should avoid these foods, but just be aware that the bioavailability of zinc from grains and plant foods, is lower than that which is available from animal foods.

Also, if you normally drink tea or coffee with your meals, I recommend that you switch to between meals only.

What About Zinc Supplements?

As I said above, you should be able to get all of the zinc you need by eating a colorful and varied diet.

However, if you decide to take zinc supplements, do not take more than a 25 mg supplement per day (unless advised by your doctor), as taking too much could be harmful.

This is the third in a series of short nutrition 101 articles (get the articles on what is iron and what is magnesium here) — please let me know if there’s something you would particularly like me to discuss in this series :-)

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Comments 6

  1. Taleen

    Fantastic article Melanie, as zinc is mineral that I knew very little about. Your information is always so relevant and helpful, so thank you so much. If you are eating eggs and and vegetables, is this enough daily zinc for your body? I don’t like the sound of the side effects of zinc deficiency.

    1. Melanie

      Hi Taleen,
      I’ve done a quick breakdown with some of the sources of zinc so you can see the kind of quantities you may be getting from your meals.

      Zinc content is in mg:

      oysters 21mg (6 medium)
      shrimp/prawns or lobster 3mg (4 oz)
      white fish 1mg (4 oz)
      Tuna 0.7mg (small can)
      Beef or lamb 5-6mg (4 oz)
      Chicken leg 3mg or chicken breast 1mg (1/2 breast)
      spinach 1.4mg (1 cup)
      squash 0.7mg (1 cup)
      broccoli 0.6mg (1 cup)
      asparagus 0.8mg (1 cup)
      beans and peas 1.5mg (1 cup)
      yoghurt 1.6 (1 cup)
      milk 1mg (1 cup)
      almonds 1mg (1oz)
      egg 0.7mg (1 egg)
      brown rice 1.2mg (1 cup)
      tofu 2mg (1/2 cup)
      pumpkin seeds 2mg (1/4 cup)
      sesame seeds 2.8mg (1/4 cup)
      apricots 0.6mg (2)
      orange 0.3mg
      banana 0.2mg
      apple 0.1mg

      If your diet is healthy and varied, it’s really not necessary to worry about individual nutrient intake.

      But, if someone is deficient in this mineral, this will give a little more info on good sources.

      I’m glad you find these articles helpful 🙂

  2. Robert Swilley

    I have been taking a 50mg zinc supplement in hopes of boosting my immune system. I see you recommend no more than 25mg. I guess I should break this tablet in half? I don’t want to take too much. Thanks…

    1. Melanie

      Hi Robert,
      That’s the problem with a lot of supplements these days, they are sold in “megadose” quantities. Somethings is simply a waste, but for other nutrients, like vitamin A, for example, it can be dangerous.

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