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ZINC.TXT
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1995-03-13
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VegSocUK Information Sheet
THE VEGETARIAN SOCIETY
___________________________________
ZINC
The mineral zinc is present in every part of the body and has a wide range of
functions. It helps with the healing of wounds and is a vital component of
many enzyme reactions. Zinc is vital for the healthy working of many of the
body's systems. It is particularly important for healthy skin and is
essential for a healthy immune system and resistance to infection.
FUNCTIONS
Zinc has a range of functions. It plays a crucial role in growth and cell
division where it is required for protein and DNA synthesis, in insulin
activity, in the metabolism of the ovaries and testes, and in liver function.
As a component of many enzymes, zinc is involved in the metabolism of
proteins, carbohydrates, lipids and energy.
Our body contains about 2-3 g of zinc. There are no specific storage sites
known for zinc and so a regular supply in the diet is required. Zinc is found
in all parts of our body, 60% is found in muscle, 30% in bone and about 5% in
our skin. Particularly high concentrations are in the prostate gland and
semen. Men need more zinc than women because male semen contains 100 times
more zinc than is found in the blood. The more sexually active a man the more
zinc he will require. The recommended amounts of zinc for adult men are 1/3
higher than those for women.
The first signs of zinc deficiency are impairment of taste, a poor immune
response and skin problems. Other symptoms of zinc deficiency can include
hair loss, diarrhoea, fatigue, delayed wound healing, and decreased growth
rate and mental development in infants. It is thought that zinc
supplementation can help skin conditions such as acne and eczema, prostate
problems, anorexia nervosa, alcoholics and those suffering from trauma or
post-surgery. It is always better to seek theadvice of an expert before
dosing yourself with supplements. If you choose to take a zinc supplement you
should not need more than the daily recommenced amount unless medical advice
says otherwise.
DIETARY SOURCES
Zinc is present in a wide variety of foods, particularly in association with
protein foods. A vegetarian diet often contains less zinc than a meat based
diet and so it is important for vegetarians to eat plenty of foods that are
rich in this vital mineral.
Good sources for vegetarians include dairy products, beans and lentils,
yeast, nuts, seeds and wholegrain cereals. Pumpkin seeds provide one of the
most concentrated vegetarian food sources of zinc.
Only 20% of the zinc present in the diet is actually absorbed by the body.
Dietary fibre and phytic acid, found in bran, wholegrain cereals, pulses and
nuts, inhibit zinc absorption. Phytic acid forms a highly insoluble complex
with zinc which the body cannot absorb. Cooking processes can reduce the
adverse effects of both phytic acid and dietary fibre on zinc absorption.
Baking can destroy over half the phytic acid in wholemeal bread. Zinc
deficiency occurs where a large part of the diet consists of unleavened
bread, such as Iran and other Middle East countries. High levels of the toxic
mineral cadmium can also prevent zinc absorption because these two minerals
compete for absorption. Conversely high levels of zinc in the diet can
prevent the absorption of cadmium. Various chemicals added to many processed
foods can also reduce zinc absorption eg phosphates, EDTA. A deficiency of
zinc in the diet means zinc absorption is improved.
Zinc is lost via the faeces, urine, hair, skin, sweat, semen and also
menstruation.
Good sources of zinc (single servings).
Tahini paste (20g or 2/3 oz) 1.1 mg
Pumpkin seeds (20g or 2/3 oz) 1.3 mg
Cheddar cheese (30g or 1 oz) 1.2 mg
Dried yeast (10g or 1/3 oz) 0.8 mg
Wholemeal bread (40g or 1 1/2 oz) 0.8 mg
Chickpeas (200g or 2 oz) 2.8 mg
Baked beans (225 g or 8 oz) 1.6 mg
Muesli (60 g or 2 1/4 oz) 1.3 mg
1 Fruit yoghurt (150 g or 5 1/4 oz) 0.9 mg
1 Vegeburger (100g or 3 1/2 oz) 1.6 mg
Fair sources
3 Brazil nuts (10 g or 1/3 oz) 0.4 mg
3 Dried figs (60 g or 2 oz) 0.5 mg
1 Orange (140 g or 5 oz) 0.3 mg
Peas, frozen/canned (80 g or 2 2/3 oz) 0.6 mg
Peanut butter (20 g or 2/3 oz) 0.6 mg
Potatoes, boiled (200 g or 7 oz) 0.4 mg
6 Almonds (10 g or 1/3 oz) 0.3 mg
Poor sources
Butter (7 g or 1/4 oz) 0.01 mg
Dried dates (15 g or 1/2 oz) 0.04 mg
Raisins & Sultanas (15 g or 1/2 oz) 0.01 mg
REQUIRED INTAKES
The old Recommended Daily Amounts (RDAs) have now been replaced by the term
Reference Nutrient Intake (RNI). The RNI is the amount of nutrient which is
enough for at least 97% of the population.
Reference Nutrient Intakes for Zinc, mg/day.
Age RNI
0 to 6 months 4.0 mg
7 months to 3 yrs 5.0 mg
4 to 6 yrs 6.5 mg
7 to 10 yrs 7.0 mg
11 to 14 yrs 9.0 mg
Adult men 9.5 mg
Adult women 7.0 mg
Pregnant women 7.0 mg
Breast feeding women 9.5 to 13 mg
Pregnant women do need extra zinc, but it is thought that demands are met by
increased absorption from the gut. Breast feeding mothers need extra zinc in
their diet. Breast milk contains over 2 mg of zinc in the first four months
and women need an extra 6 mg a day to cover these demands. Breast feeding
women must include a generous serving of at least one good source of zinc in
their diet each day.
The iron supplements routinely prescribed for pregnant women when there is no
sign of anaemia may compromise zinc status. This is because the interactions
between essential minerals are complex and too much of one may cause an
imbalance of another.
Excess zinc is toxic. Too much zinc will interfere with the metabolism of
other minerals in the body, particularly iron and copper. Symptoms of zinc
toxicity occur after ingestion of 2 g of or more and include nausea, vomiting
and fever.
MEAL PLAN
Sample one day's meal plan to meet the RNI of 9.5 mg for an adult man.
Breakfast
Bowl of muesli with milk 1.32 mg
1 slice of toast 0.8 mg
Lunch
Baked beans (225g or 8 oz) 1.57 mg
2 slices of toast 1.6 mg
Cheese (30 g or 1 oz) 1.2 mg
(or Pumpkin seeds, 20 g or 2/3 oz)
Evening meal
Potatoes, boiled (200g or 7 oz) 0.4 mg
Peas (80 g or 2 2/3 oz) 0.56 mg
1 Vegeburger (100g or 3 1/2 oz) 1.3 mg
1 Fruit yoghurt 0.94 mg
Total zinc intake 9.69 mg
___________________________________
//
This article is copyright to the Vegetarian Society (UK), but may be freely
copied for non-commercial use provided it is kept intact, not altered
and these lines are included.
For futher information contact: The Vegetarian Society, Parkdale, Dunham Road,
Altrincham, Cheshire WA14 4QG, England. Tel: (England) 061 928 0793
email: vegsoc@vegsoc.demon.co.uk
//
[The text of this file was obtained from the Vegetarian Society (UK) in
March 1995.]