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Zinc
What is zinc’s role?[i]
Zinc is a trace mineral that is found in every living cell in the body
Ø Zinc plays a central role in the immune system
Ø Nearly 100 enzymes require zinc as a catalyst for activity
Ø During cell division, zinc is needed for DNA and RNA production and activity
How common is zinc deficiency?
In developing countries, where the diet is primarily grains that interfere with zinc absorption, delayed and stunted growth in children is a significant problem.
In Canada, there are no laboratory tests sensitive enough to diagnose mild or moderate zinc deficiency. Therefore, the problem generally isn’t diagnosed. However, from the Food Habits of Canadians study, we know that almost one out of four Canadians have diets that are low in zinc.
|
Percent of Canadians not meeting Estimated Average Requirement for Zinc[ii], [iii] People with intakes below the Estimated Average Requirementare at risk of developing zinc deficiency.
|
||
Females |
Males |
|
| 18-34 years |
26 |
14 |
| 35-49 years |
22 |
21 |
| 50-65 years |
23 |
34 |
What are the consequences of zinc deficiency?[iv]
Ø Fewer natural killer cells and decreased resistance to infectious diseases
Ø Impaired taste and smell
Ø Stunted growth
Ø Impaired memory or cognitive ability
Infants born with zinc deficiency may:
Ø Have lower birth weight and delayed growth
Ø Experience impaired immune system development and receive fewer antibodies from their mothers’ placenta
Ø Have below average motor and cognitive development at 6 months of age
How much zinc should Canadians have?[v]
Recommended Daily Allowances for Zinc |
||||||
| Infants | Children | Teen Boys & Men | Teen Girls & Women* | |||
| 0-6 months | 2 mg/day | 1-3 yrs | 3 mg/day | 11 mg/day | 14-18 yrs | 9 mg/day |
| 7-12 months | 3 mg/day | 4-8 yrs | 5 mg/day | 19+ yrs | 8 mg/day | |
| 9-13 yrs | 8 mg/day | |||||
* When pregnant or breastfeeding, women need an additional 5 mg/day.
Vegetarians who don’t eat meat, fish or poultry need up to 50% more zinc.
What foods contain zinc?
Zinc absorption is best when the diet contains meat, fish and poultry. Phytates, a compound found in plant foods such as legumes, soy and whole grains, inhibit absorption.
Foods Containing Zinc |
||
| More than 5 mg/serving*Providing half the Recommended Daily Allowance in one serving | 3.1 to 5 mg/serving* | 1.1 to 3.0 mg/serving* |
| Most beef cutsGround beef
Beef liver Oysters |
Most pork cutsBaked beans | Lentils and kidney beansMussels and shrimp
Chicken, dark meat Cheddar cheese Rice, white |
* Serving sizes are those recommended in Canada’s Food Guide to Healthy Eating.
Are zinc supplements recommended?
Although short term zinc supplementation is used to correct an identified deficiency or as part of a multiple vitamin/mineral pregnancy supplement, there are problems associated with using zinc supplements alone, particularly for a long period of time.
Ø High doses (40 mg/day or more) can be toxic
Ø Zinc may interfere with the absorption of other nutrients such as copper
Ø Chronic use of zinc supplements can suppress immune response and decrease HDL cholesterol in men
Do zinc lozenges help prevent colds?
Despite many studies, there is no conclusive evidence that zinc lozenges reduce the duration of common colds.
For more information on zinc and zinc deficiency contact www.beefinfo.org or call 1-888-248-2333
[i] Hambidge, M. Human Zinc Deficiency. J Nutr 130: 1344s-1349s, 2000
[ii] Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. National Academy Press, 2001.
[iii] Gray-Donald K et al. Food Habits of Canadians Study, unpublished results, 2002.
[iv] Shankar AH and AS Prasad. Zinc and immune function: the biological basis of altered resistance to infection.
Am J Clin Nutr 68 supplement: 447s, 1998.
[v] Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. National Academy Press, 2001.
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