ZINC CONTENT OF SELECTED COMMON FOODS
Food (3 ounces, cooked, lean only) Zinc (mg)Beef Shank crosscuts, simmered 8.9Chuck, arm
pot roast, braised 7.4Roundtip, roasted 6.0Sirloin, broiled 5.5Top round, broiled 4.7Ground,17%
at, broiled 4.6Top loin, broiled 4.4Tenderloin, roasted 4.1Eye round, roasted 4.0
Pork Shoulder, blade, Boston roasted 3.6Ham, boneless, 5% fat 2.4Tenderloin, roasted 2.2
Loin chop, broiled 2.0
Lamb Leg, shank half, roasted 4.3Loin, roasted 3.5
Veal Sirloin, braised 4.0Cutlet, pan fried 2.4
Chicken Liver, simmered 3.7Dark meat, roasted 2.4Light meat, roasted 1.0
Turkey Dark meat, roasted 3.8Light meat, roasted 1.7
Fish Tuna, light meat, canned .7Ocean perch, dry heat .5Halibut, dry heat .5
Salmon, sockeye, dry heat .4
Shellfish Oysters, 6 medium, raw 49.8Crab, Alaskan king, moist heat 6.5Shrimp, moist heat 1.3
Food Zinc (mg)Dairy Yogurt, lowfat, plain, 1 cup 2.2Products Milk, lowfat, 1 cup 1.0
Cheese, cheddar, 1 ounce .9Cheese, cottage, lowfat, 1/2 cup .4
Cereals Raisin bran, dry, 1 cup 3.0Shredded wheat, dry, 1 cup 1.0Oatmeal, instant, 1/2 cup .6
Cream of wheat, instant, 1/2 cup .2Corn flakes, dry,1cup .2
Grains Bran muffin, 1 medium .6Brown rice, cooked, 1/2 cup .6Bagel,1-31/2 inch .6Whole wheat
bread, 1 slice .5White rice (enrich), cooked, 1/2 cup .4White bread (enrich),1slice .2
Fruits Banana, 1 medium .2Apricots, dried, 7 halves .2Prunes, dried, 3 medium .1
Orange,1medium .1Apple,1medium .1Raisins, 2 tablespoons .1
Vegetables Peas, green, cooked, 1/2 cup .9Potato, baked w/skin, 1 medium .6
Corn, cooked, 1/2 cup .4Broccoli, raw, 1/2 cup .2Spinach, raw, 1 cup .2Lettuce, iceberg, chopped,
1 cup .1Carrots, raw, 1 medium .1
Beans/ Baked beans, canned, plain, 1/2 cup 1.8
Legumes Chickpeas, boiled, 1/2 cup 1.3Kidney beans, boiled, 1/2 cup .9
Meat Egg, substitute, 1/2 cup 1.6
Substitutes ofu, raw, 1/2 cup 1.0Peanut butter, 2 tablespoons .9Egg, whole, cooked, scrambled
.6
Food Sources of Essential Minerals and Trace Elements
Calcium
Milk and milk products are the most important dietary sources of Calcium (Ca) followed
by cereal products and fruits and vegetables1,2. Tinned fish, such as sardines, are rich
sources of Ca but do not make a significant contribution to intake for most people. Foods
of plant origin are not particularly good sources of Ca, but the growing number of Ca
fortified products is leading to wider range of rich dietary sources of Ca. How we absorb
Ca from various foods is currently under investigation at the Institute of Food Research.
This research may provide useful information for the prevention of
osteoporosis.Chromium----The richest dietary sources of Chromium (Cr) are spices such as
black pepper, brewer's yeast, mushrooms, prunes, raisins, nuts, asparagus, beer and wine.
Refining of cereals and sugar removes most of the native Cr, but stainless steel vessels in
contact with acidic foods may contribute additional Cr. Beverages, including milk, may provide up
to one-third of the daily intake of Cr. Copper---The Copper (Cu) content of food is affected by
its geographical origin and the processing conditions it undergoes prior to consumption. Foods
high in Cu include liver, kidney, shellfish, wholegrain cereals and nuts. Soft or acidic water
passing through copper pipes can also contribute Cu to the diet. At the Institute of Food Research
we are carrying out research to provide information on the dietary copper levels required to
maintain health.Iodine—The concentration of Iodine (I) in plants and animals is greatly influenced
by the soil. In the Western world, milk and its products are good sources of I 3, especially where
cattle feed iodinization occurs (e.g. Finland, Norway and the UK). Seafood also contains large
amounts of I from seawater. Bread, which contains iodate products as dough strengtheners, and
processed foods containing iodized salt are also good sources of inorganic iodide. In countries
where I is deliberately added to diets to prevent the disease goitre, iodized salt has been the main
source, and in this form we can absorb nearly 100%4 of the I. Excess I intake can result in
hyperthyroidism5 when the thyroid gland is overstimulated.Iron-----Iron (Fe) is widely distributed in
meat (30 - 70% is haem iron, i.e. in the red blood haemoglobin), vegetables and cereals, but the
concentration in milk and fruits and vegetable is low6. The Fe content per se of individual foods
has little meaning since the efficiency with which we can take up and use Fe (i.e. it's
bioavailability) varies considerably. We are investigating Fe bioavailability from various
foods.Magnesium====Magnesium (Mg) is widely distributed in plant and animal foods, especially
nuts, legumes, green vegetables (present as the inorganic ion of chlorophyll), cereals and
chocolate. Hard drinking water may also be an important source of dietary
Mg.Manganese===Relatively high concentrations of Manganese (Mn) have been reported in
cereals (20 - 30mg/kg), brown bread (100 - 150mg/kg), nuts (10 - 20mg/kg), ginger (280mg/kg)
and tea (350 - 900mg/kg dry tea)7. Concentrations of Mn in crops are dependent on soil factors
such as acidity (pH) whereby increasing soil pH decreases plant uptake of Mn8. Animal tissues
contain very low amounts of Mn.Selenium===The concentration of Selenium (Se) in food varies
between different food items and reflects soil Se content9 and soil type. Alkaline soils favour plant
uptake of selenites whilst acid soils and areas rich in iron and calcium restrict uptake by plants.
Animal tissues show smaller variations in Se than vegetable. Cereals, seafood and meat products
are the richest sources of Se and are the main contributors to the daily Se intake, whereas
vegetables, fruits and beverages are generally low in Se9. Low dietary Se intake levels have been
reported for people living in low Se areas9 and for population groups with special or restricted
feeding regimens10.Only limited information is available on the Se species in food.
Selenomethionine (Se-Met) has been identified as a major Se compound in wheat11, soyabeans12
and high Se-yeast13, while selenocysteine (Se-Cys) has been identified in several mammalian
proteins14. Inorganic Se forms have been identified in drinking water15. We are currently
undertaking research to investigate the absorption and metabolism of the different forms of Se
found naturally in foods.Zinc=====The Zinc (Zn) content of foods varies from up to 2000mg/kg
fresh weight in oysters to below 5mg/kg in refined foods or foods with a high fat content. In
legumes and animal products Zn is associated with protein components. In meat products the Zn
content to some extent follows the colour of the meat, so that the highest content, approximately
50mg/kg, is found in lean red meat, at least twice that in chicken. In cereals, most of the Zn is
found in the outer fibre-rich part of the kernel, thus the degree of refinement determines the total
Zn content. Wholegrain products provide 30 - 50mg/kg while a low extraction rate wheat flour 8 -
10mg/kg. The major dietary determinants for the total Zn intake are the amount of animal protein,
the extraction rate of the cereals and the fat content of the diet. We have carried out research at
the Institute to determine the importance of zinc in growth and development.
Zinc
Zinc is a metal that is normally found in small amounts in nature. It is used in many commercial
industries and can be released into the environment during mining and smelting (metal
processing) activities. People living near smelters or industries using zinc could be exposed to
higher levels of zinc by drinking water, breathing air and touching soil that contains the metal.
Exposure to high levels of zinc over long periods of time may cause adverse health effects.
How does zinc get into the environment?
Although zinc occurs naturally, most zinc finds its way into the environment because of human
activities. Mining, smelting metals (like zinc, lead and cadmium) and steel production, as well as
burning coal and certain wastes can release zinc into the environment. A common use for zinc is
to coat steel and iron as well as other metals to prevent rust and corrosion; this process is called
galvanization. High levels of zinc in soil may result from the improper disposal of zinc-containing
wastes from metal manufacturing industries and electric utilities. In soil, most of the zinc stays
bound to the solid particles. When high levels of zinc are present in soils, such as at a hazardous
waste site, the metal can seep into the groundwater.Industries also can release dust containing
higher levels of zinc into the air we breathe. Eventually, the zinc dust will settle out onto the soil
and surface waters. Rain and snow also can remove zinc dust from the air. Most of the zinc in
lakes, rivers and streams does not dissolve, but settles to the bottom. Some fish in these waters
may contain high levels of zinc. High levels of zinc in the soil, water and air are often found along
with high levels of other metals like lead and cadmium.
How might I be exposed to zinc?
Zinc can enter the body if you eat foods or drink water or other beverages containing zinc, or if
you breathe zinc dust or fumes from the air. Very small amounts of zinc enter the body through
skin contact. People living near a smelter or another zinc-producing industry who have a private
well are most likely to be exposed through their drinking water. They also may be exposed to zinc
through the air they breathe, or through vegetables grown in contaminated soils. Through
frequent hand-to-mouth contact, children also can be exposed to zinc by playing in contaminated
soils.Foods naturally contain zinc but vary greatly in their zinc content. Very small amounts of the
zinc in food are absorbed by the body. Drinking beverages stored in metal cans or drinking water
that flows through metal pipes coated with zinc also are sources of zinc exposure.
How can zinc affect my health?
Zinc is an essential nutrient needed by the body for growth, development of bones, metabolism
and wound-healing. Too little zinc in the diet also can cause adverse health effects such as loss of
appetite, decreased sense of taste and smell, lowered ability to fight off infections, slow growth,
slow wound-healing and skin sores.A short-term illness called metal fume fever can result if
workers breathe very high levels of zinc dust or fumes. This condition, which usually lasts from 24
to 48 hours, causes chills, fever, excessive sweating and weakness. Long-term effects of
breathing zinc dust or fumes are not known.Eating or drinking too much zinc in a short period of
time can lead to adverse health effects, such as stomach cramps, nausea and vomiting. Eating
large amounts of zinc for longer periods may cause anemia, nervous system disorders, damage
to the pancreas and lowered levels of “good” cholesterol. There is no evidence that zinc causes
cancer in humans.
How can I reduce my exposure to zinc?
Knowing possible sources of zinc in your environment is important in reducing exposure. Children
are particularly at risk if they play in contaminated soil. Limiting play in contaminated areas and
planting grass to provide ground cover can greatly reduce exposure. Practice good hygiene
habits by washing children’s hands and faces often, especially before eating and bedtime.
Practice good housekeeping techniques by removing shoes before entering your home to prevent
tracking contaminated soils inside, and vacuum carpets, rugs and upholstery often.If you live near
a smelter or another zinc-producing industry and your drinking water comes from a private well,
you may want to have the water tested for zinc. Public water systems are tested for zinc on a
regular basis. If you live near a zinc smelter or another industry that produces zinc, you also may
want to have your garden soil tested.
Is there a medical test that can tell me if I have been exposed to zinc?
Zinc can be measured in blood, feces, urine and hair. Different tests may be able to show the
type of exposure to zinc. High levels of zinc in the blood or feces might show a recent high
exposure. Zinc levels measured in hair would show long-term exposure. However, these tests are
not routinely used. If you think you have been exposed to elevated levels of zinc, contact your
doctor for more information.
Abstract Spinach (Spinacia oleracia) and amaranth (Amaranthus tricolor) leaves were stored in
polyethylene bags and without packing for 24 and 48 hours in a refrigerator at 5 and 30 °C in
polyethylene bags. The fresh leaves were also dried (oven and sun); blanched (5, 10 and 15 min)
and cooked in an open pan and a pressure cooker. The processed leaves were analysed for total
and extractable calcium and zinc content. The Ca and Zn content of these leaves varied from
1320 to 2120 and 11.70 to 12.60 mg/100 g DM and the percentage HCl-extractability was 77.82
to 81.92 and 85.16 to 86.15, respectively. No significant effects of drying and storage were
observed on total Ca and Zn content and HCl-extractability while blanching and cooking resulted
in significant improvement of HCl-extractibility of these two minerals. Thus, cooking and blanching
are good ways to improve the HCl-extractibility of Ca and Zn.
Key words Amaranth - Blanching - Cooking - Drying - Spinach - Storage - Total and HCl-
extractable calcium and zinc
