Nutrition 12 ch 12
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What are trace elements / minerals?
Elements or minerals which your body needs <100 mg of per day.
What are the trace elements / minerals?
- some others
What is hemoglobin?
A protein in red blood cells which contains iron and binds with oxygen and carries it through the body.
What is myoglobin?
A protein in muscle cells which has iron and can bind to oxygen.
Iron can be part of the diet in two forms; heme and nonheme. What kinds of foods is heme iron found in and how well is heme iron absorbed?
Heme iron is found in animal products - in meat, fish, and poultry. Myoglobin in muscle tissue and hemoglobin in the blood of animals contains iron and is then consumed. It is absorbed very well. Its absorption is not affected by other minerals.
Heme iron gets its name because it is iron that is bound to heme protein. Heme protein is part of what makes hemoglobin.
What kinds of foods can nonheme iron be found in and how well is it absorbed?
Nonheme iron is found in plants like leafy green vegetables, legumes, whole and enriched grains. Nonheme iron is not absorbed as well as heme iron.
Why is bioavailability of iron such a concern?
Iron can bind with oxalate, tannins, phytates which can reduce or prevent its absorption. Other minerals can compete for absorption and reduce amount of iron absorbed.
How is nonheme iron different from heme iron?
- Nonheme iron is iron that is not bound to heme protein, hence the name "nonheme". Nonheme iron is found in plants like leafy greens and legumes. Nonheme iron is found in two types:
- Ferric ( Fe3+ ) and Ferrous ( Fe2+ ). Ferrous iron is more easily absorbed.
- Acidic food like orange juice can inmprove the absorption of nonheme iron.
- Phytates, oxalates, tannins, and dietary fiber can interfe with the absorption of nonheme iron.
How does the body use heme iron?
- Iron consumed in heme and nonheme form is absorbed into cells lining intestinal tract.
- In the intestinal wall cells the ferrous iron is released from the heme protein it was bound to.
- Some of the ferrous iron is bound to ferritin and stays in intestinal wall cells as stored iron.
- Some of the iron in intestinal wall cells will bind to transferrin to be transferred to other parts of the body.
- To bind to transferrin iron must be converted to feric ( Fe3+ ) form. Copper-containing proteins are necesarry for this to happen.
- Once bound to transferrin the iron can be transported to other parts of the body.
- Destinations in the body need to have transferrin receptors for transferrin to be able to deliver iron to them.
- It is transferred to bone, liver, and other body cells.
- Excess iron is stored primarily in the liver.
- Red blood cells ( containing hemoglobin, heme proteins, and the iron in them ) are broken down by the spleen, liver and other organs and the iron is reused.
Where can iron be found in the body?
- Intestines - Ferritin in cells lining intestinal tract is a protein that binds to iron to store it in the intestines.
- Muscle - Myoglobin in muscle cells is a protein which iron binds to to store it in muscle tissue.
- Blood - Transport proteins called transferrin in blood bind to iron to transport it to different parts of body.
- Blood - Hemoblobin, the oxygen carrying protein in blood, binds to iron.
What are some functions of iron?
Carrying oxygen from lungs to cells of body . Iron is part of both hemoglobin protein in red blood cells which carries oxygen through blood and myoglobin protein which stores oxygen in muscle cells for use later.
Iron is needed by proteins involved in ATP production and electron transport chain.
Iron is part of the enzyme catalase which protects cells from oxidative damage by hydrogen peroxide.
Ever seen what happens when hydrogen peroxid comes into contact with blood? It foams. Catalase ( which needs iron to work ) in the blood breaks down hydrogen peroxide ( which can damage body's cells ) into water and oxygen. The bubbles you see are bubbles of oxygen.
What are RDAs for iron intake?
RDAs for iron depend on a person's sex, age, whether or not they are pregnant.
Average RDA for men is around 10mg / day.
- Pre-menstrual age females - 8mg / day.
- Menstruating females 14 - 18 yo - 15mg / day.
- Menstruating females 19 - 50 yo - 18mg / day.
- Pregnant women - 27mg / day.
- Lactating women - 10mg / day.
- Vegetarian men and women - 14mg / day.
- Vegetarian female teens - 27mg / day.
- Vegetarian menstruating females - 32mg / day.
The specific amounts aren't so important to memorize, just realize it's different for different people and that mentruating women, pregnant women, and vegetarians need more iron.
The body needs iron for hemoglobin in red blood cells ( RBCs ) to bring oxygen to all tissues in the body. Not enough iron can lead to iron deficiency anemia where not enough hemoglobin is made and RBCs are microcytic ( very small ). Not enough hemoglobin means not enough oxygen to body tissues.
Symptoms of iron deficiency anemia are fatigue, weakness, headache, difficulty maintaining body temperature.
Iron is also needed by the immune system and not enough iron can lead to difficulty fighting off infection.
Iron is needed for the development of fetuses and not enough iron can lead to adverse pregnancy outcomes like low birth weight.
Pica is also thought to be brought upon by iron deficency. Pica is an abnormal urge to eat non-food items like dirt, clay, chalk, paint chips, ash.
Why is iron deficiency often not diagnosed until long after a person has not been getting enough?
Symtoms will not be noticed until after deficiency has occured because iron can be depleted from intestinal tract and liver but still be present in blood stream.
Where will iron first be depleted from in an iron deficient person?
Ferritin ( storage form of iron in intestinal wall ) will first be depleted, used up so that there can still be iron in the blood. Transferrin in blood plasma second. Myoglobin in muscles an hemoglobin in bloodstream last.
What are some groups at risk for iron deficiency?
Women of reproductive age lose blood through menstruation and iron along with it. Adolesent boys who are growing rapidly and need iron for muscle and bone growth. Children and adolescents growing a lot need iron for development. Athletes - running a lot and having feet hitting pavement can actually destroy red blood cells in bottom of feet.
Acute toxicity - iron poisoning can be caused by taking too many iron suppliments at once. It is expecially dangerous for children taking mom's iron suppliments, ingesting too much at once for such a small system.
Acute iron poisoning can cause damage intestinal lining, change body pH, cause shock and liver failure.
Iron overload / chronic iron poisoning can occur from cosuming too much iron but it is most common in people with hemochromatosis, a hereditary condition which causes a person to absorb too much iron. The excess iron in their system can cause the skin to darken, weight loss, fatigue, weakness and abdominal pain. If not stopped it can cause heart and liver damage, cancer, diabetes or other conditions. Hemochromatosis is managed simply by removing blood from the sufferer.
What are some functions of zinc?
- Involved in the function of over 300 enzymes.
- Necesarry for enzymes that made DNA.
- Needed for sperm production.
- Important for fetal growth.
- Involved in taste perception.
- Component of SOD ( superoxide dismutase ).
What is SOD / superoxide dismutase?
An enzyme that breaks down superoxide ( a free radical which can do damage to cells ) into oxygen ( good ) and hydrogen peroxide ( bad ). The hydrogen peroxide is then broken down by catalase into water and more oxygen.
Zinc is needed by SOD for it to work.
What is metallothionein?
A protein in cells lining the intesteinal tract ( mucosal cells ) which regulate the amount of zinc absorbed. When zinc intake is low, low levels of metallothionein are produced and zinc is moved pretty easily into the bloodstream. When zinc intake is too high, more metallothionein is produced, binds to zinc, and prevents ( or slows ) its absorption.
Zinc is excreted in pancreatic and intestinal juices, when zinc levels in the body are low, it can be reabsorbed.
What are some possible causes of zinc deficiency?
- Acrodermatitis enterophica is a genetic defect that causes a person to have limited zinc absorption which can lead to zinc deficiency.
- Babies fed formula that lacks zinc or enough zinc can suffer from deficiency.
- Unleavened bread ( bread made without yeast ) has a lot of phytates in it which can bind to zinc and prevent it absorption. Bread made with yeast reduces the phytate content and more of the zinc is absorbable.
What are some symptoms of zinc deficiency?
Poor growth and development, skin rash, hair loss, impaired reproduction, impaired immune system.
Just 1 to 2 grams of zinc taken at once can cause vomiting, loss of appetite, diarrhea, cramps, and headaches. 50 to 300 mg per day can decrease immune system, interfere with absorption of copper, and reduce HDL cholesterol.
What are RDAs for Zinc?
- 11mg / day for men.
- 8mg / day for women.
UL 40mg / day.
What are some functions of copper?
- Part of SOD superoxide dismutase antioxidant enzyme.
- Necesarry for the neurotransmitters noepnephrine and dopamine.
- Part of the protein that lets zinc bind to transferrin.
Not enough copper in the diet is uncommon but when it happens can lead to anemia. Copper is a necessary part of the protein that binds iron to transferrin so iron can be carried through the blood. Without enough copper there isn't enough binding protein to attach iron to transferrin and iron doesn't get moved through the body very well.
Copper deficiency can also lead to bone abnormalities. Copper is part of the enzyme necessary for cross-linking connective tissues. Without copper, the enzyme can't work and tissues in bone, gums, etc. are malformed and lead to scurvy-like symptoms.
Copper toxicity from eating normal food is very rare. However acidic food stored in copper containers can leach copper into the food, copper contamination in food or drinking water can also cause toxicity. Symptoms are abdominal pain, vomiting, diarrhea.
RDAs for copper...
900Ug / day
UL 10mg / day
What are some functions of selenium?
- It regulates thyroid hormones.
- Acts as an antioxidant.
Not enough selenium in the diet can cause someone to have a greater chance of having Keshan disease which causes an enlarged heart, heart tissue to become fibrous, and decreased heart function. It most often occurs in areas where food is grown in soil with low amounts of selenium.
Too much selenium can cause hair and nails to become brittle and fall out, skin rash, fatigue, and irritability.
RDAs for selenium...
55ug / day
UL - 400ug / day
What are some functions of iodine?
Iodine is necessary for regulating thyroid hormones that affect growth, development, ane metabolic rate.
Not enough iodine reduces the production of thyroid hormones. As a result, metabolic rate slows causing fatigue and weight gaine. It can also cause a simple goiter which is an enlargement of the thyroid gland.
Iodine deficiency can also increase the risk of stillbirth in pregnant women and lead to cretinism in children of iodine deficient mothers. Cretinism causes conditions similar to mental retardation as well as physical deformation and growth problems.
Two causes of goiter formation...
Iodine deficiency - not enough iodine reduces the amount of hormones the thyroid gland produces. This triggers the release of thyroid stimulating hormone which is supposed to cause the thyroid to produce hormones again. Since there is no iodine to regulate the release of hormones the thyroid gland just gets larger.
Too much iodine intake can cause goiters, too. Too much iodine can block the thyroid gland's ability to make hormones which leads to the release of more thyroid stimulating hormone but since hormone can't be made because of too much iodine the thyroid gland just enlarges.
What are some functions of fluoride?
Fluoride is important for the formation of teeth and bones. Fluoride also helps prevent tooth decay.
Fluoride helps prevent tooth decay, making the enamel more resistant to acid. Not enough fluoride in the diet can lead to tooth decay.
Too much fluoride in the diet can cause fluorosis which causes teeth to become stained, cracked and pitted. Too much fluoride can also cause bone problems and affect kidney function.
How much of the population of California has fluorinated water?
Less than 49%
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