Nutrition Chapter 13 (Exam 3)

Trace minerals what are they and their functions?

• Iron

  • Zinc

    • Iodine

      • Fluoride

• Less than 5gram of trace minerals are in the body

• Daily dietary needs are less than 20milligram

• Amount in plants depends on the amount contained in the soil in which the plant was grown

• Found in whole grains, legumes dairy, meat, and seafood

• Processing removes trace minerals found in the bran and germ of grains

• Stable in cooking

• Bioavailability of trace minerals can vary according to:

  • Individual nutritional status

  • Other foods eaten

  • Form of the mineral

  • Presence of other minerals (compete with others for absorption-same ionic charge)

• Some are recycled in the body and can be used repeatedly, such as iron

• Most trace minerals function as cofactors

  • Form part of an enzyme complex

  • Metalloenzymes: Active enzymes that contain one or more metal ions that are essential for their biological activity

  • Iron, copper, and selenium (cofactors within antioxidant enzyme systems)

Metalloenzymes

• Active enzymes that contain one or more metal ions that are essential for their biological activity

What is Fluoride

• Is not classified as essential because the body does not require it for normal growth and development

• Is found naturally in plants and animals, and often added to water supply

• Is mostly absorbed in the small intestine

Metabolic Functions of Fluroide

• Develops and maintains strong healthy teeth

  • Forms fluoroapatite which helps harden the outer layer of the tooth (the enamel) and makes the tooth more resistant to damage (tooth decay)

  • ___from food, beverages, and toothpaste repairs eroded enamel

  • Inhibits the interaction between bacteria and carbohydrate, thereby reducing acid production

  • ____in saliva helps remineralize the hydroxyapatite structure of the tooth

• Helps maintain strong bones

  • Combined with calcium and vitamin D

    • Increases bone mineral density

    • Reduces the incidence of osteoporosis

Food Sources of Fluoride

• Best source is fluoridated water and beverages and foods made with fluoridated water

  • Faucet water is best

  • Some, but not all, bottled water contains fluoride

• Tea (particularly decaffeinated tea)

  • Tea leaves accumulate fluoride

Fluoride Toxicity and Deficiency

• Toxicity

  • Fluorosis in teeth and bones

  • Condition caused by excess amounts of fluoride, resulting in mottling of the teeth

• Deficiency

  • Increased susceptibility to dental caries

What is Zinc?

• Found in very small amounts in almost every cell of the body

  • Mostly in bone and muscle

• Involved in the function of more than 100 metalloenzymes, including those used for protein synthesis

• Absorption is reduced when:

  • High levels of nonheme iron are present

  • Phytates and diets high in fiber are consumed

• Consuming animal proteins improves zinc absorption

• Helps wounds heal

• Needed for DNA and RNA synthesis

  • Turns genes on and off

• Keeps the immune system healthy

  • May reduce duration of the common cold

  • Acts as an antioxidant

  • Reduces inflammation

  • Part of enzymes and proteins that repair skin cells and enhance their proliferation

• Improves taste perception

• May prevent age-related macular degeneration

Zinc Toxicity

• Toxicity

• Symptoms: Stomach pain, nausea, vomiting, and diarrhea

• Excess can:

  • Interfere with copper absorption

  • Suppress the immune system

  • Lower HDL cholesterol

Zinc Deficiency

• Deficiency

  • Delayed growth in children

  • Hair loss

  • Loss of appetite

  • Impaired taste of food

  • Diarrhea

  • Delayed sexual maturation

  • Impotence

  • Skin rash

What is Iodine?

• Iodide (I^-), the ionic form of iodine, is an essential mineral

• Mandatory salt iodization significantly reduced the incidence of goiter in the United States

Metabolic Functions of Iodine

• Component of the thyroid hormones

  • Thyroid gland traps iodine and uses it to make the thyroid hormones thyroxine (T₄) and triiodothyronine (T₃)

• Thyroid hormones help regulate:

  • Metabolic rate

  • Reproduction

  • Energy (ATP) production in the TCA cycle

  • Nerve, muscle, and heart function

Iodine Toxicity and Deficiency

• Toxicity

  • Impairs thyroid function and reduces the synthesis and release of thyroxine

• Deficiency:

  • Simple goiter: Enlarged thyroid gland

  • Secondary deficiency and goiter

    • Goitrogens: Substances in food that reduce the use of iodine by the thyroid gland, resulting in goiter

      • Rutabagas, cabbage, soybeans, and peanuts

• During pregnancy

  • Damage to brain of the developing baby

• Cretinism (congenital hypothyroidism)

  • Severe deficiency

  • Abnormal sexual development

  • Mental retardation

  • Dwarfism

Heme Iron

• Part of:

  • Hemoglobin (in red blood cells)

  • Myoglobin (in muscle cells)

  • Cytochromes (in electron transport chain)

• Found in animal foods

  • Meat, poultry, fish

• Reduced form-Ferrous iron (Fe⁺²)

• More easily absorbed

Nonheme Iron

• Found in plant foods

• Grains, vegetables, enriched breads, and fortified cereals

• 80% of iron consumed in foods (100% for vegans)

• Oxidized form-Ferric iron (Fe⁺³)

Iron Bioavailability (Heme Iron and Nonheme Iron)

• Heme Iron → animal foods

• Nonheme Iron → plant foods

• The bioavailability of iron is influenced by several factors

• The molecular form of the iron, iron status of the individual, and the types of food eaten at the same time

• Heme iron is two to three times more bioavailable than nonheme iron

• Iron is absorbed in the enterocyte and attached to ferritin in the enterocytes (Figure 13.1)

Nonheme Iron Absorption

Enhance ___ Iron Absorption

• Sufficient hydrochloric acid in the stomach

• The form of iron in the food; heme iron is more easily absorbed than nonheme iron

• Increased need for iron (blood loss, pregnancy, growth)

• Vitamin C in the small intestine at the same time

• Presence of MFP factor (meat, fish, poultry)

Decrease Iron Absorption

• Phytates in cereal grains (dietary fiber)

• Oxalates

• Polyphenols (tea or coffee)

• Reduced hydrochloric acid in stomach

• Excess use of antacids

• Excess minerals such as calcium, zinc, and magnesium

Iron Absorption and Transport

• Hormonal regulation of iron absorption

  • Hepcidin: Hormone that controls iron absorption and transport

    • High iron stores:

      • When the body has high levels of iron stored, it signals to the liver that no more iron is needed in the blood

      • liver produces more hepcidin to inhibit ferroportin from transporting iron out of the enterocyte into the portal blood

  • Low iron stores:

    • When the body has low levels of iron stores, it signals to the liver that more iron is needed in the blood

    • Hepcidin levels are decreased

• Stored iron affects iron absorption

  • Low iron stores increase intestinal iron absorption

    • Less ferritin (protein that stores iron) is produced

      • more iron will be absorbed directly into the bloodstream

  • High iron stores decrease intestinal iron absorption

    • More ferritin and hepcidin are produced

      • Block iron from absorption and to store the iron in the enterocytes

  • Excess iron is excreted in the feces

Iron Homeostasis

• Body does not need iron

• Iron is stored in the ferric form (Fe3+; oxidized form) and binds itself to ferritin (protein that stores iron) or hemosiderin (protein that stores additional iron)

• Body needs iron

• Iron is released from the ferritin and transported into the portal vein. Then, the iron attaches itself to transferrin, a protein carrier which transports iron throughout the body

Metabolic Functions of Iron

• Participates in oxidation-reduction reactions

  • Also referred to as redox reaction (transfer of electrons)

  • Example; Fe⁺² ↔ Fe⁺³ +e^-

(Fe2→ reduced form)

(Fe3→ oxidized form)

• Major component of hemoglobin and myoglobin

  • Transports oxygen and carbon dioxide

• Participates in energy metabolism

  • Performs as a cofactor in enzymes in energy metabolism

  • Part of cytochromes in the mitochondria

• Immune function

  • Needed to produce lymphocytes and macrophages

  • Protects cell membranes from free radical damage

• Needed for brain function

  • Helps enzymes involved in the production of neurotransmitters

    • Dopamine, epinephrine, norepinephrine, and serotonin

  • Deficiency during the early years of childhood is associated with decreased cognitive ability during the later school years.

Iron Toxicity

• Symptoms include constipation, nausea, vomiting, and diarrhea

• __ poisoning in children

  • Accidental consumption of supplements containing iron is the leading cause of poisoning deaths in children under age 6

• More likely to occur with supplementation or in individuals with the genetic disorder hemochromatosis

• ___overload

  • Buildup of excess stores of iron over several years

  • Can damage organs and tissues

  • Hemochromatosis can cause overload

    • A genetic disorder in which individuals absorb too much dietary iron

Iron Deficiency and interactions with other nutrients

• ___-deficiency anemia

  • Hemoglobin levels decrease

  • Oxygen delivery to tissues diminished

• Symptoms include fatigue, weakness, reduced ability to fight infection.

• Populations at risk

  • Pregnant women

  • Menstruating women and teenage girls (especially those with heavy blood losses)

  • Preterm or low birth weight infants

  • Older infants and toddlers

• Interactions with other nutrients: zinc, calcium, ascorbic acid

What are Nutrient Deficient Anemias?

• Anemias

  • Blood lacks enough healthy, normal-sized red blood cells to deliver oxygen to the tissues.

  • Classified by the size of red blood cells

• Most anemias are caused by nonnutritional factors

  • Losing too much blood

  • Insufficient red blood cell production

  • Red blood cells being destroyed

• Other causes

  • Low nutrient intake

  • Malabsorption

  • Abnormal metabolism of nutrients

Microcytic Anemia

• Small red blood cells that lack color

• Lacks hemoglobin

• Most common cause

  • Iron deficiency

• Other causes

  • Vitamin B₆ deficiency

Macrocytic Anemia

• Fewer, abnormally large red blood cells

• Lacks sufficient hemoglobin

• Most common cause

  • Folate or vitamin B₁₂ deficiency

• Other causes

  • Pernicious anemia (inability to absorb vitamin B12)

Microcytic/ Iron Deficiency Anemia

• Iron-deficiency anemia is the most common type of microcytic anemia and occurs when there is insufficient iron in the body

• Women are at a higher risk than men

• In men and postmenopausal women:

  • Occurs due to blood losses from ulcers, excess aspirin use, specific cancers

• Signs and symptoms

  • Fatigue, pale skin color, irritability, shortness of breath, sore tongue, brittle nails, pica, headache in the frontal lobe, blue tinge to the whites of the eyes, decreased appetite

  • Children can develop irreversible intellectual impairment

• Testing for iron-deficiency anemia involves simple blood tests.

  • Complete blood count or total iron-binding capacity

• Treatment for iron-deficiency anemia

  • Iron supplements are needed

    • Ferrous sulfate, ferrous gluconate, or ferrous fumarate are most easily absorbed

    • Take iron with orange juice or other vitamin C source

    • Avoid taking with milk or antacids

Macrocytic/ Pernicious Anemia

• A form of ____ anemia caused by the body's inability to absorb vitamin B₁₂

• Cause:

  • Typically, a lack of intrinsic factor due to gastritis or an autoimmune reaction that attacks the parietal cells of the stomach

• Symptoms:

  • Diarrhea or constipation, pale skin, problems concentrating, shortness of breath

• Treatment:

  • Intramuscular injections of vitamin B₁₂