chapter 12 notes - trace elements

zinc supplements

- Are often marketed to improve immune function and enhance fertility and sexual performance, but are not effective if the person consuming them is not deficient in zinc.

zinc toxicity

- Can be toxic if taken in excess - Too much zinc interferes with absorption of copper (stimulates increased mucosal cell metallothionein which binds copper more strongly than zinc) and impairs function of copper-zinc superoxide dismutase. - Excess zinc impairs the immune system and lowers HDL. - Zinc lozenges may affect the cold virus, but 4 lozenges in a day can exceed the UL and actually decrease the immune function. - Those with a genetic defect in zinc absorption (acrodematitis enteropathica) can survive well when supplemented with very large doses of zinc, but it puts them at risk for copper deficiency. - People with Wilson's disease have a problem with excretion of copper and copper accumulates. • Supplemental zinc acetate prevents copper absorption and is a good treatment for Wilson's disease.

summary: chromium

- Chromium is found in the liver, brewer's yeast, nuts, and whole grains. - Chromium is needed for normal insulin action and glucose utilization - Overt chromium deficiency Is not a problem in the U.S> population - Chromium supplements are marketed to control blood sugar and increase lean body mass Controlled trials have reported no dietary chromium toxicity in humans.

how chromium functions in the body

- Chromium is involved in carbohydrate an d lipid metabolism. - Without chromium, more insulin is required so less glucose is taken up by the cell. - With chromium, glucose uptake by the cell is enhanced.

iodine toxicity

- Consuming diets with food high in goitrogens, such as turnips, rutabaga, cabbage, cassava and millet, limit the bioavailability of iodine • If boiled, goitrogens are lost in the water ad are reduced in the foods. - Goiter from excessive iodine can occur if iodine intake increases dramatically - The UL for adults is 1100 micrograms of iodine per day. Iodine toxicity is possible.

12.10 Molybdenum (Mo)

- Deficiencies are very rare except in people fed by TPN long term. - Molybdenum is readily absorbed from foods and excreted in urine and bile. - Required as a cofactor for a number of enzymes. - Participates in the metabolism of the sulfur-containing amino acids and nitrogen-containing compounds in DNA and RNA - Involved in the production of uric acid and detoxification of various compounds. Summary: - Molybdenum is a cofactor for enzymes involved in the metabolism of the amino acids methionine and cysteine and nitrogen-containing compounds such as DNA and RNA.

manganese deficiency and toxicity

- Deficiency studies have been performed in animals, but there have been few human studies. - One man accidently fed a manganese free diet for 6 months and some volunteer men who consumed a manganese diet for 39 days experienced dermatitis, and altered blood cholesterol, calcium, and phosphorus levels. - Toxicity symptoms have been observed in miners who breathed high levels of manganese.

12.8 Chromium chromium in the diet

- Dietary sources of chromium include brewer's yeast, liver, nuts, and whole grains. - Refined carbohydrates are poor sources because chromium is lost in processing - Cooking in stainless steel can increase food's chromium content.

copper deficiency

- Elevated blood cholesterol has been reported with copper deficiency. - Copper deficiency is not common, but most often manifests as anemia because iron cannot be transported by transferrin - Copper deficiency symptoms are similar to those of vitamin C deficiency and scurvy because the enzyme needed for cross-linking of collagen for bone matrix requires copper - Other symptoms: degeneration of heart muscle, nervous system, changes in hair color and structure, impaired growth and immune function.

zinc in the body

- Essential in the diet for growth and development - It is found in the cytosol, in cellular organelles and in the nucleus - Zinc is involved in the functioning of over 300 different enzymes - Superoxide dismutase (SOD) vital for protecting cells from free radical damage) needs zinc. - Zinc is needed to maintain adequate levels of metallothionein proteins which also scavenge free radicals. - Storage and release of insulin mobilization of vitamin A from the liver (retinol binding protein) and stabilization of cell membranes need zinc - Zinc influences hormonal regulation of cell division and growth and repair of tissues, the activity of the immune system and development of sex organs and bone. - Zinc absorption and transport • High zinc intake: more zinc is lost when mucosal cell dies • Low zinc intake: less zinc is lost when mucosal cell dies. - Zinc fingers and gene expression: finger-like structures called zinc fingers allow nuclear receptor proteins that bind to vitamin A to interact with the regulatory region of a gene and thus affect gene expression. Similar nuclear receptor proteins are essential for the activity of vitamin D and certain hormones.

summary: selenium

- Excellent dietary sources of selenium include seafood, eggs, and organ meats. The selenium content of plant foods depends on the selenium content of the soul where they are grown, and the selenium content of animal products is affected by the amount of selenium in their feed. - Selenium protects against oxidative damage as an essential part of the enzyme glutathione peroxidase. Glutathione peroxidase destroys peroxides before they can form free radicals. Adequate dietary selenium reduces the need for Vitamin E. - Severe selenium deficiency is rare except in regions with very low soil selenium content and limited diets. In China, selenium deficiency contributes to the development of a heart condition known as Keshan disease. Low selenium intake has been linked to increased cancer risk. - Selenium supplements are marketed with claims that they will protect against environmental pollutants, prevent cancer and heart disease, slow the aging process , and improve immune function. Supplements that increase intake above the RDA do not provide additional benefits

iron in the body

- Ferritin is the major iron storage protein - Tranferritin is an iron transport protein in the body - Iron is essential or 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. - The iron from the iron-transferrin complex (in blood plasma) is taken up by cells after first binding to transferrin receptors. - Iron is stored bound to ferritin in the liver, spleen, and bone marrow and to some extent in blood plasma. - Levels of ferritin in blood give an indication of iron stores - When ferritin concentrations in the liver become high and exceed storage capacity, some is converted to an insoluble storage protein called hemosiderin.

zinc deficiency

- First observed in the 1960s in Iranian and Egyptian males who experienced a syndrome of growth depression and delayed sexual development • Their diets were high in zinc, but the grains and unleavened breads they ate were high in phytates. Zinc was bound by phytates and couldn't be absorbed. • When provided with supplemental zinc, the symptoms resolved. - Symptoms include: poor growth and development, skin rashes, hair loss, diarrhea, neurological changes, impaired reproduction, skeletal abnormalities, and reduced immune function - This condition can be caused by a genetic defect in zinc absorption and metabolism, feeding a total parenteral nutrition (TPN) solution without zinc and consuming a diet low in protein and high in phytates. - It may also occur in individuals with kidney disease, sickle cell anemia, alcoholism, cancer, and AIDS.

12.9 Fluoride Fluoride in the diet

- Fluoride is present in small amounts in almost all soil, water, plants, and animals. - The most common sources of fluoride fluoridated water, tea, marine fish eaten with their bones (canned salmon or sardines), toothpaste. - Water companies often report fluoride in parts per million (ppm), 1 mg/liter = 1 ppm.

summary: copper

- Good sources of copper in the diet include organ meats, seafood, nuts, and seeds. - The absorption of copper is affected by the presence of other minerals in the diet. The zinc content of the diet can have a major impact on copper absorption. - Copper function in a number of important proteins that affect iron and lipid metabolism, synthesis of connective tissue, and antioxidant protection. Copper is transported in the blood bound to proteins such as ceruloplasmin. - A copper deficiency can cause anemia and connective tissue abnormalities. Copper toxicity from dietary sources is extremely rare.

summary: zinc

- Good sources of zinc include red meat, eggs, dairy products, and whole grains. Zinc from animal sources is better absorbed than that from plant foods. Phytates inhibit zinc absorption from many plant sources. - Zinc absorption is regulated by zinc transport proteins that determine how much zinc is in the mucosal cells and by metallothionein, a protein that binds zinc in the mucosal cell. When zinc intake is high, more metallothionein is synthesized and zinc absorption is limited. - Zinc is needed for the activity of many enzymes, including a form of the antioxidant superoxide dismutase. Many of the functions of zinc are related to its role in gene expression. Zinc is needed for tissue growth and repair, development of sex organs and bone, proper immune function, storage and release of insulin, mobilization of vitamin A from liver, and stabilization of cell membranes, - Zinc deficiency results in poor growth, delayed sexual maturation, skin changes, hair loss, skeletal abnormalities, and depressed immunity. - Since copper binds more tightly to metallothionein than zinc, an excess of zinc, which stimulates metallothionein synthesis, can trap copper I the mucosal cells, causing a copper deficiency. - When administered within 24 hours of the onset of common cold symptoms, supplemental zinc is lozenge form can reduce the duration and severity of cold symptoms.

how fluoride functions in the body

- Important for dental health. In 1930s, association between adequate fluoride content of drinking water and reduced prevalence of dental caries was noted. - Fluoride is absorbed into body in proportion to the content in diet up to about 80-90%. Calcium-rich foods reduce the bioavailability of fluoride. - Fluoride has a high affinity for calcium and so is associated with calcified tissue such as bones and teeth. - Tooth enamel is more resistant to acid that cases tooth decay when fluoride has been incorporated. - Fluoride has its greatest effect on dental caries prevention during maximum tooth development (early in life to ~ 13 years of age).

iodine deficiency

- In early 1900s, iodine deficiency was common in central US and Canada. This was eliminated with addition of iodine to salt. - Goiter = enlargement of the thyroid gland - In iodine deficiency, no thyroid hormones are made, TSH release continues, result = goiter - Iodine deficiency during pregnancy may result in cretinism in offspring. Cretinism results in stunted growth and poor mental development - Cretinism and goiter are rare in North America, but worldwide 600 million people have goiter and 1.5 billion are at risk for iodine deficiency.

12.7 iodine

- Iodine was one of the first if not the first mineral recognized as essential for man and animals.

copper functions in the body

- Iron and lipid metabolism - Connective tissue synthesis - Maintenance of heart muscle - Immune and central nervous system function - Essential component of superoxide dismutase - Copper may be important in helping to prevent certain types of anemia. - Zinc can decrease the bioavailability of copper. - Copper absorption and transport: 1. High levels of dietary zinc stimulate the synthesis of metallothionein 2. Metallothionein preferentially binds copper, limiting its absorption 3. The copper bound to metallothionein is lost when the mucosal cell dies.

summary: iron

- Iron is found in both plants and animal foods. Heme iron, the easily absorbable form, is found in animal products. Non-heme iron, which is less well absorbed, comes from both animal and plant sources. - The amount of iron that is absorbed form the diet depends on the type of iron and the presence of other dietary components. The absorption of non-heme iron can be increased by consuming it with meat, Vitamin C, or other acids; its absorption is decreased by consuming it with foods containing fiber, phytates, oxalates, and tannins. - Iron homeostasis is regulated at the intestine. If iron stores are low, more iron is transferred from the mucosal cells to the blood and bound to transferring for transport to body cells. When body stores are high, less iron is transported from the mucosa into the blood and more is bound to ferritin and lost when mucosal cells die. - Iron functions as part of hemoglobin, which transports oxygen in the blood, and myoglobin, which enhances the amount of oxygen available during muscle contraction. Iron is also a component of proteins involved in ATP production and is needed for activity of the antioxidant enzyme catalase. - When iron is deficient, adequate hemoglobin cannot be made, resulting in an anemia characterized by small, pale red blood cells. Iron deficiency anemia is the most common nutritional deficiency worldwide. - Iron can be toxic. Ingestion of a single large dose can be fatal. The accumulation of iron in the body over time causes heart and liver damage and contributes to diabetes and cancer. The most common cause of chronic iron overload is hemochromatosis, a genetic disorder in which too much iron is absorbed.

iron in the digestive tract

- Is part of several proteins in the citric acid cycle - Is a component of the electron transport chain (cytochromes) - Participates in drug metabolism - Enhances immune function - Is part of an enzyme catalase (destroys hydrogen peroxide before it can form free radicals) - Iron functions as part of hemoglobin (in red blood cells) and myoglobin (in the muscle cells). These molecules are important for their oxygen-carrying or oxygen-holding capacity. - Iron helps carry oxygen in the blood and store oxygen in the muscle cells. - Heme iron: myoglobin in red meat provides heme iron and vies the meat its red color • In hemoglobin and myoglobin, the iron ion is in the Fe2+ state - Iron absorption • Absorption of iron is regulated at the gut level. • When the need for iron is greater the percent of iron absorbed will increase. • When iron needs are greater more iron is transferred from ferritin to transferrin and moves into the blood.

12.5 Manganese (Mg) Manganese in the body

- Manganese is constituent of some enzymes and 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 located inside mitochondria - Manganese homeostasis is regulated by absorption and excretion: low intake = higher absorption and less excretion - Manganese is eliminated by secretion into bile. - the best sources of manganese are whole grains and nuts.

summary: manganese

- Manganese is necessary for the activity of some enzymes, including a form of the antioxidant enzyme superoxide dismutase. Manganese is involved in amino acid, carbohydrate, and lipid metabolism.

iron in the diet

- Meat, poultry, fish = both heme and non-heme Fe - Flour, meat, raisins - Plant foods = only non-heme iron - Both plant and animal foods = good sources of iron (spinach, lentils)

how iodine functions in the body

- More than half the iodine in the body is found in the thyroid gland. - Iodine is an essential component of thyroid hormones, including thyroxin. - Thyroid hormones promote protein synthesis and regulate basal metabolic rate, growth and development. - Thyroid hormones 1. Thyroid hormones (T4 and T3) circulate in the blood bound to plasma proteins 2. T4 and T3 enter the cell, where a selenium-containing enzyme converts T4 to T3. 3. T3 enters the nucleus and binds to a nuclear receptor protein 4. The T3-receptor protein complex binds to a regulatory region of a target gene. 5. Transcription of gene is turn on, increasing the amount of mRNA made. 6. mRNA directs translation, increasing the synthesis of the protein coded by this gene. 7. The cellular functions and body processes affected by this protein are increased. • Low thyroid hormones → TSH o Iodine available → thyroid hormone made → normal thyroid levels inhibit TSH release o Iodine deficient → no thyroid hormones made → TSH releases continues → thyroid gland enlarges forming a goiter - When the supply of iodine is adequate, the body can produce the needed tyroid hormones

Summary: fluoride

- Most of the fluoride in the diet in the United states comes from fluoridated drink water and toothpaste. - Fluoride is necessary for the maintenance of bones and teeth. Adequate dietary fluoride helps prevent dental caries in children and adults. - Low fluoride intake increases the risk of dental caries. Excess fluoride causes dental fluorosis in children.

copper toxicity

- Most toxicity problems have come from people consuming acidic foods or drinks that have been stored in copper containers or if the water supply is contaminated.

12. 4 copper copper in the diet

- Nuts, seeds, seafood, organ meats (kidney and liver), chocolate, and whole grain foods - The soil content affects the amounts of copper in plant foods.

chromium deficiency

- Rare in the U.S. - Persons administered TPN long-term with no added chromium or malnourished children have demonstrated symptoms of chromium deficiency. - Symptoms included: impaired glucose tolerance with diabetes-like symptoms, elevated blood glucose, and increased insulin levels.

how selenium functions in the body

- Selenium's essential role was recognized in 1970s when It was found to prevent a heart disorder in children in China living in regions with low selenium levels. • The disease is known as Keshan disease, affecting the heart muscle and is a combination of viral infection and selenium deficiency. - It is now known to play an important role in body's antioxidant defenses. - Selenium absorption is efficient and homeostasis is regulated by excretion in the urine. - Selenium functions in association with proteins known as selenoproteins with selenium as a part of an amino acid selenocysteine. - Several selenoproteins are enzymes that protect cells from oxidative damage. - The most well known selenoprotein is glutathione peroxidase. • This enzyme neutralizes provides so they cannot form free radicals and this reduces need for Vitamin E, which neutralizes free radicals once they have formed.

meeting iron needs

- Supplements contain non-heme iron - If supplements are not effective, more animal flesh foods may need to be eaten - A UL has been set at 45 mg/day from all sources. - Benefits and risks of iron supplements • Claim: increases energy • Actual benefits or risks: • Needed to make hemoglobin to deliver oxygen to tissues • Supplements = beneficial if Fe is deficient • High disease can cause constipation, liver damage, and death.

selenium deficiency

- Symptoms include muscular discomfort and weakness. - There may be a connection between diets low in selenium and higher incidences of cancer. - Nail and hair brittleness and loss occur in people living in regions of China with high selenium levels in the soil (intake of 5 mg/day). - Selenium deficiency causes muscular discomfort, weakness, and in some cases Keshan disease

selenium toxicity and supplements

- Symptoms include: nausea, diarrhea, abdominal pain, fingernail, and hair changes, nervous system abnormalities, fatigue, and irritability. - Selenium supplements are marketed with claims that they will protect against environmental pollutants, prevent cancer and heart disease, slow the aging process, and improve immune function. - Intakes above the RDA, however, in individuals who are not selenium deficient will not provide additional benefits

summary: iodine

- The best sources of iodine in the diet are seafood, foods grown near the sea, and iodized salt. - Iodine is an essential component of thyroid hormone, which promote protein synthesis and regulate basal metabolic rate, growth, and development - When iodine is deficient, continued release of thyroid-stimulating hormone causes the thyroid gland to enlarge, forming a goiter. Iodine deficient during pregnancy causes a condition in the offspring known as cretinism, which is characterized by growth failure and developmental disability. Iodine deficiency during childhood and adolescence can impair mental function. Iodized salt ahs virtually eliminated iodine deficiency in North America. Although salt iodization is being used successfully worldwide to prevent iodine deficiency, iodine deficiency remains a world health problem. - Acute toxicity can occur with very large doses of iodine. Chronically high intakes of iodine can cause an enlargement of the thyroid gland that resembles goiter.

Iodine in the diet

- The iodine content of food depends on the soil where plants are grown or where animals graze. - So near the ocean or sea is higher in iodine than soil inland. - Most of the iodine in the diet comes from iodized salt (100 micrograms of salt). Iodized salt is salt fortified with iodine. "Natural" sea salt may be very low in iodine. - Iodine also comes in our diet from contaminants and additives in food • Dairy products may contain iodine because of iodine-containing additives used in cattle feed and the use of iodine-containing disinfectants on cows, milking machines and storage tanks • Iodine-containing sterilizing agents are also used in food service establishments and iodine is used in dough conditioners and some food colorings.

iron toxicity

- The most common form of iron overload is hemochromatosis. This is an inherited condition and is the most common genetic disorder in Caucasians. - People with this condition absorb iron better than others. - Identified individuals will need to consume less iron and may also need blood withdrawal. - Iron is essential for cellular metabolism but too much can be toxic. - 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 as iron accumulates in tissues such as the heart and the liver. - Iron toxicity can also occur acutely with a single large dose. - One of the most common types of childhood poisoning is from iron overdose due to consumption of iron-containing supplements - Iron containing products must carry this warning and should be stored out of reach of children who may consume them in excess.

recommended fluoride intake

- The optimal amount of fluoride makes teeth resistant to decay and doesn't cause fluoride. - Breast milk is low in fluoride and ready made formulas are made with unfluoridated water. Therefor the American Academy of Pediatrics recommends fluoride supplementation infants. - Supplementation is also recommended for children if their drinking water contains less than 0.3 mg per liter of fluoride - Fluoride supplements may help prevent osteoporosis.

12.6 Selenium (Se) Selenium in the diet

- The selenium content of plant foods, such as grains and seeds, depends on the selenium content of the soil in which they are grown.

iron deficency

- The trace mineral most likely to be under consumed on a world-wide basis is iron - It is estimated that as much as 80% of the world's population may be iron deficient and 30% (2 billion people) suffer from iron deficiency anemia. - Athletes have higher needs because of iron losses due to prolonged training (increased turnover of muscle). - When iron is deficient, hemoglobin cannot be produced. - Women of reproductive age are t risk as well as infants, children and adolescents because of growth and increased needs. - When there is insufficient hemoglobin, red blood cells are microcytic and hypochromic and unable to deliver sufficient oxygen to the tissues. This is known as iron deficiency anemia. - Result in poor pregnancy outcomes, impaired development and growth - Hematocrit = volume of red blood cells in blood - Symptoms include: fatigue, headache, decreased work capacity, inability to maintain body temperature in cold environment, decreased resistance to infection • Last thing to drop is iron in red blood cells

chromium supplements and toxicity

- There is no UL for chromium but there is concern about chromium picolinate supplements marketed to increase muscle mass causing toxicity.

fluoride deficiency

- Too little fluoride makes teeth more susceptible to dental caries.

fluoride toxicity

- Too much fluoride (intakes of 2-8 mg/day or greater in children) causes teeth to appear mottled, a condition called fluorosis. - Excessive fluoride ingestion can result in a condition called fluorosis. Chronic ingestion of toothpaste containing fluoride can result in this condition. - Death has been reported with an intake of 5-10 g/day.

12.1 trace minerals in our diet

- Trace elements are: iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium, and molybdenum. - Require in amounts <100 mg/day - Provide a variety of essential structural and regulatory roles. - Trace elements have been difficult to study, as they have small requirements and are difficult to remove from the diet. - Iodine is needed to make thyroid hormones - Iron is needed to carry oxygen to body cells (hemoglobin) and store oxygen within cells (myoglobin). - Fluoride is needed for strong teeth and bones - Selenium, copper, zinc, iron, and manganese are cofactors for antioxidant enzymes. - Bioavailability is a concern for trace elements because small amounts in the diet can become bound to phytates, fiber, tannins, and oxalate. - Interactions among minerals can affect trace mineral absorption. o A deficiency of copper can reduce iron absorption and transport • Deficiencies are more likely in areas of the world where people eat only locally grown foods • Soils can be low or high in various trace minerals • This is not usually a problem with modern transportation systems because we consume food from all over the country and the world.

conclusion

- Trace mineral perform a variety of structural and regulatory roles - Iron and iodine deficiencies are the most common trace mineral deficiencies on a world-wide basis. - Phytates, tannins, oxalate, and fiber can bind trace minerals and reduce their absorption.

summary: trace minerals in our diet

- Trace minerals are required by the body in an amount of 100 mg or les per day or present in the body in an amount of 0.01% or less of body weight. They include iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium, and molybdenum.

recommended iodine intake

- Why fortify salt? - Salt was selected as vehicle for added iodine because it is a food item consistently consumed by majority f the population at risk. It can be added to salt uniformly, inexpensively, and in a form well utilized by the body.

zinc in the digestive tract

- Zinc can be bound by phytates, affecting bioavailability. - Zinc is secreted into the GI tract in the pancreatic and intestinal juices. If the body levels are low then more zinc is reabsorbed.

Zinc in the diet

- Zinc is abundant in red meat, liver, eggs, dairy products, vegetables, and some seafood. - Whole grains are good sources of zinc, but zinc is lost form refined grains during processing and is not added back - Grain products leavened with yeast provide more zinc because the yeast leavening reduces the phytate content. - From animal sources is better absorbed than zinc from plant source

12.3 Zinc (Zn)

the most abundant intracellular trace elements

12.2 iron (Fe)

• Iron from the diet is absorbed into the intestinal mucosal cells. • Heme iron is more efficiently absorbed than non-heme iron. • Non-heme iron absorption is enhanced by ascorbic acid and small amounts of meat in the diet. • Iron cookware can be a source of non-heme iron in the diet: - Spaghetti sauce cooked in a glass pan provides ~0.6 mg iron. - Spaghetti sauce cooked in an iron skillet provides ~5.7 mg iron.

factors that increase risk of deficiency

• Women of child-bearing age lose iron due to menstruation. Pregnant women, infants, children, and teens need additional iron for growth and development. • Diets that are low in red meat, phytates, and fibers. • Individuals living in poverty are less likely than others to consume adequate iron. Intestinal parasites cause blood loss, which increases iron losses.