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Chapter 12 THE TRACE ELEMENTS

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Page 1: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Chapter 12THE TRACE ELEMENTS

Page 2: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Trace Elements Talk The trace elements include iron, zinc, copper,

manganese, selenium, iodine, fluoride, chromium and molybdenum.

They are required in amounts less than 100 mg per day.

Trace elements have been difficult to study, as they are difficult to remove from the diet.

Rate of bioavailability is a concern for trace elements.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 3: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron in the Diet

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 4: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron Talk Hemoglobin is the iron-containing component of the

blood. Iron from animal products is heme iron. Iron from plant products is nonheme iron. Iron cookware can be a source of nonheme iron in the

diet. Heme iron is more efficiently absorbed than nonheme

iron. Iron from the diet is absorbed into the intestinal mucosal

cells.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 5: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Heme Iron Absorption

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 6: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron in the Body Ferritin is the major iron storage protein. Transferritin is an iron transport protein in the blood. Hemosiderin is an insoluble iron storage compound

produced by the body when iron exceeds the storage capacity of ferritin.

Iron is essential for the delivery of oxygen to cells. Two oxygen-containing proteins, hemoglobin and myoglobin, contain iron.

Most of the iron in the body is part of hemoglobin.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 7: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

DRIs for Iron

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 8: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

DRIs for Iron

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 9: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron Deficiency When iron is deficient, hemoglobin cannot be

produced. When there is insufficient hemoglobin, red blood

cells are microcyctic and hypochromic and unable to deliver sufficient oxygen to the tissues. This is known as iron deficiency anemia.

It is estimated that as much as 80% of the world’s population may be iron deficient and 30% suffer from iron deficiency anemia.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 10: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron and Zinc in the Canadian Diet

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 11: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iron Toxicity and Overload Iron is essential for cellular metabolism, but too much

can be toxic. A UL has been set at 45 mg/day from all sources. Iron poisoning can be life-threatening. It can damage the

intestinal lining and cause abnormalities in body pH, shock and liver failure.

Iron overload can happen over time and accumulates in tissues such as the heart and the liver.

The most common form of iron overload is hemochromatosis.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 12: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Zinc in the Canadian Diet

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 13: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Zinc in the Canadian Diet CCHS suggests that a number of Canadians are

not meeting their zinc requirements. The richest sources of zinc are found in animal products

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 14: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Zinc in the Diet Vegetarians are more vulnerable to having

inadequate zinc intakes. Vegans my be 50% more vulnerable due to the lower bioavailability of zinc from vegan sources. Wise food choices are necessary.

Canadian regulations also require some foods, such as simulated meat products and beverages derived from legumes, nuts, cereal grains and potatoes, to be fortified with zinc. This information will be listed in the Nutrition Facts Table.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 15: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Zinc Talk Zinc is essential in the diet for growth and development. Zinc from animal sources is better absorbed than zinc

from plant sources. Zinc can be bound by phytates, affecting bioavailability. Zinc is the most abundant intracellular trace element. Zinc is involved in the functioning of over 300 different

enzymes, including superoxide dismutase, important for protecting cells from free radical damage.

Zinc can be toxic if taken in excess.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 16: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Copper Talk Copper may be important in helping to prevent certain

types of anemia. The richest dietary source of copper is organ meat.

Seafood, chocolate, nuts, seeds and whole-grain foods are also good sources.

Zinc can decrease the bioavailability of copper. The RDA for copper for adults is 900 micrograms per

day.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 17: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Manganese Talk The best sources of manganese are whole grains and

nuts. Manganese is a constituent of some enzymes and an

activator of other enzymes. Manganese-requiring enzymes are involved in amino

acid, carbohydrate and cholesterol metabolism, cartilage formation, urea synthesis and antioxidant protection.

Manganese, like copper and zinc, is needed for the activity of a form of superoxide dismutase.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 18: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Selenium in the Diet

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 19: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Selenium Talk The selenium content of plant foods, such as grains and

seeds, depends on the selenium content of the soil in which they are grown.

Selenium deficiency can lead to Keshan disease, affecting the heart muscle.

Symptoms of selenium deficiency include muscular discomfort and weakness.

There may be a connection, still being researched, between diets low in selenium and higher incidences of cancer.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 20: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iodine Talk The iodine content of food depends on the soil where

plants are grown or where animals graze. Soil near the ocean or sea is higher in iodine than soil

inland. Most of the iodine in the diet comes from iodized salt.

Iodized salt is salt fortified with iodine. “Natural” sea salt may be very low in iodine.

More than half the iodine in the body is found in the thyroid gland.

Iodine is an essential component of thyroid hormones, including thyroxine.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 21: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Thyroid Hormones

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 22: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iodine and Thyroid Hormones

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 23: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iodine Talk When the supply of iodine is adequate, the body can

produce the needed thyroid hormones. The RDA for iodine for adult men and women is 150

micrograms per day. The RDA for iodine is higher during pregnancy and lactation.

Consuming diets high in goitrogens, such as cabbage, cassava and millet, limits the bioavailability of iodine.

Iodine deficiency may result in hereditary cretinism. The UL for adults is 1100 micrograms of iodine per day.

Iodine toxicity is possible.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 24: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Iodine Talk All salt sold for household use in Canada,

including sea salt, must be iodized (trace element iodine added).

Since the introduction of iodized salt in Canada, iodine intake has been adequate and iodine deficiency rare.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 25: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Chromium Talk Dietary sources of chromium include brewer’s yeast,

liver, nuts and whole grains. Cooking in stainless steel can increase food’s chromium

content. Chromium is involved in

carbohydrate

and lipid metabolism.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 26: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Fluoride Talk Fluoride is important for dental health. Fluoride is present in small amounts in almost all

soil, water, plants and animals. The most common sources of fluoride are

fluoridated water, tea, marine fish eaten with their bones, such as canned salmon or sardines, and topical toothpaste.

Calcium-rich foods reduce the bioavailability of fluoride.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 27: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Fluoride Talk (continued) 43% of the Canadian population receive fluoridated

water, but there are substantial regional differences. Fluoride intake has also increased due to the

widespread use of fluoride toothpaste and fluoridated water in foods and beverages that are distributed in nonfluoridated areas.

Dental caries remain a public health problem. However, increased fluoride intake and advances in dental care have dramatically improved the dental health of the public.

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 28: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Fluoride Talk (continued)

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 29: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Fluoride Talk (continued)

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 30: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Fluoride Toxicity

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 31: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Summary of Trace Elements

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 32: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Summary of Trace Elements (continued)

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 33: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Benefits and Risks of Trace Element Supplements

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 34: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Benefits and Risks of Trace Element Supplements

Copyright 2012, John Wiley & Sons Canada, Ltd.

Page 35: Chapter 12 THE TRACE ELEMENTS. Trace Elements Talk The trace elements include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and

Copyright

Copyright © 2012 John Wiley & Sons Canada, Ltd.

All rights reserved. Reproduction or translation of this work beyond that permitted by Access Copyright (The Canadian Copyright Licensing Agency) is unlawful. Requests for further information should be addressed to the Permissions Department, John Wiley & Sons Canada, Ltd. The purchaser may make back-up copies for his or her own use only and not for distribution or resale. The author and the publisher assume no responsibility for errors, omissions, or damages caused by the use of these programs or from the use of the information contained herein.

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Copyright 2012, John Wiley & Sons Canada, Ltd.