© 2011 pearson education, inc. 12 nutrients involved in blood health and immunity

© 2011 Pearson Education, Inc.

12Nutrients Involved

in Blood Health and Immunity


Blood

• Functions• Transports nutrients and oxygen to cells• Removes waste products generated from

metabolism


Components of Blood

• Erythrocytes—red blood cells transport oxygen through the body

• Leukocytes—white blood cells are key to our immune system

• Platelets—cell fragments assist in blood clotting

• Plasma—fluid portion of the blood maintains adequate blood volume


Nutrients Maintain Healthy Blood

• Iron• Zinc• Copper• Vitamin K• Folate

• Vitamin B12


Iron

• Iron is a trace mineral• Component of oxygen-carrying hemoglobin

and myoglobin (muscle)• Component of cytochromes, electron carriers

within the metabolic pathways for energy production from carbohydrates, fats, and protein


Maintaining Iron Homeostasis

• Regulation of iron digestion, absorption, transport, storage, and excretion

• Factors that alter iron digestion and absorption • Individual’s iron status• Level of dietary iron consumption• Type of iron in foods • Amount of stomach acid for digestion• Dietary factors enhance or inhibit absorption


Iron

• Two types of iron in foods• Heme iron—found only in animal-based foods

and more absorbable• Non-heme iron—not as easily absorbed


Iron

• Factors that promote iron absorption• Meat factor • Stomach acids• Vitamin C


Iron

• Factors that impair iron absorption• Phytate (legumes, rice, and whole grains)• Polyphenols (oregano, red wine, tea, coffee) • Vegetable proteins• Fiber• Calcium

• Bioavailability of iron from vegan diet is 10%, vs. typical Western diet’s 14−18%


Iron

• Iron transport• Transferrin: iron-transport protein in blood • Receptors on cells transport iron into cells

• Iron storage• Ferritin and hemosiderin help meet iron needs• Liver, bone marrow, and spleen


Iron

• Regulation of total-body: • Iron absorption • Iron losses• Storage and recycling of iron


Iron

• Recommended intake• RDA varies based on age and gender• 8 mg/day for adult men• 18 mg/day for adult women,19−50 years• 27 mg/day for pregnant women

• Sources of iron• Meat, poultry, fish, clams, oysters, liver, enriched

or fortified cereals and breads• Supplements


Too Much Iron

• Accidental iron overdose: most common cause of poisoning deaths in children

• Symptoms: nausea, vomiting, diarrhea• Hemochromatosis: excessive absorption of

dietary iron and altered iron storage• Treatment: reduce dietary iron, avoid high

vitamin C intake, blood removal


Not Enough Iron

• Most common nutrient deficiency in the world• High risk: infants, young children, adolescent

girls, premenopausal and pregnant women• Poor dietary intakes• Iron losses in blood and sweat• Diets high in fiber or phytates that bind iron• Low stomach acid• Poor iron absorption (poor gut health or

dietary supplements with high mineral levels, e.g., calcium)


Stages of Iron Deficiency

1. Iron depletion is caused by a decrease in iron stores

2. Iron-deficiency erythropoiesis occurs with decreased iron transport

3. Iron-deficiency anemia results in reduced normal, healthy red blood cell production, decreased size, inadequate hemoglobin


Zinc

• Zinc is a trace mineral

• Functions of zinc• Component of enzymes (heme synthesis)• Maintain structural integrity and shape of proteins • Assist in regulating gene expression


Zinc

• Absorption increases with need: growth, sexual development, pregnancy

• Dietary factors inhibit zinc absorption• High non-heme iron intake • Phytates and fiber (whole grains, beans)

• Dietary factor enhances zinc absorption• Animal-based protein


Zinc

• RDA: 8 mg/day for women, 11 mg/day for men

• Sources of zinc• Red meats, some seafood, whole grains, enriched

grains and cereals


Zinc

• Too much zinc• Toxicity can occur from supplements• Symptoms: intestinal pain, cramps, nausea,

vomiting• Depressed immune function• Decreased high-density lipoprotein concentrations• Interference with copper and iron absorption.


Zinc

• Not enough zinc• Deficiencies are uncommon in the United States• Symptoms: growth retardation, diarrhea, delayed

sexual maturation, hair loss, impaired appetite, infections

• Lack of good assessment parameters for zinc


Copper

• Copper is a trace mineral• Functions of copper• Required for iron transport• Cofactor in energy metabolism and for connective

tissue production• Part of superoxide dismutase antioxidant enzyme

system• Regulates neurotransmitters (serotonin)


Copper

• Factors that promote copper absorption• More copper is absorbed with low-copper diet

• Factors that impair copper absorption• High zinc intakes • High iron intakes


Copper

• Recommended intake• RDA for adults is 900 µg/day

• Sources of copper• Organ meats, seafood, nuts, seeds, whole-grain

foods


Copper

• Too much copper• Toxicity is not well studied in humans• Symptoms: abdominal pain, nausea, diarrhea,

vomiting, liver damage (Wilson disease)

• Not enough copper• Copper deficiency is rare• Symptoms: anemia, reduced white blood cells,

osteoporosis (children—bone demineralization)


Vitamin K

• Vitamin K is a fat-soluble vitamin important for both bone and blood health

• Function of vitamin K• Coenzyme assists in synthesizing blood

coagulating proteins: prothrombin and procoagulants, factors VII, IX, and X


Vitamin K

• Factors that promote vitamin K absorption• Gastrointestinal bacteria produce vitamin K• Dietary need depends on intestinal health

• Factors that impair vitamin K absorption• Impaired dietary fat absorption


Vitamin K

• Recommended intake• AI for adults is 90−120 µg/day

• Sources of vitamin K• Green leafy vegetables, such as collard greens,

kale, spinach, cabbage• Soybean and canola oils


Vitamin K

• Too much vitamin K• No known side effects

• Not enough vitamin K• Deficiency is rare• Blood fails to clot, bleeding, hemorrhaging• Fat malabsorption • Newborns lack intestinal bacteria to produce

vitamin K (injection at birth)


Folate

• Folate is a water-soluble vitamin

• Functions of folate (coenzyme)• DNA synthesis, amino acid metabolism• Cellular division and differentiation

• Functions with B12 and B6 metabolism


Folate

• Factors that alter folate digestion, absorption, and balance• Bioavailability depends on its source: better from

supplements than from food • Alterations in folate status mimic those of iron• Four states of folate deficiency


Folate

• Recommended intake• RDA : 400 µg/day adults, 600 µg/day during

pregnancy

• Sources of folate• Fortification to minimize birth defects: enriched

breads, flours, pasta, grain products• Liver, spinach, lentils, oatmeal, asparagus• Heat-sensitive; leached out in cooking liquid


Folate

• Too much folate• Toxicity can result from supplements

• Toxicity can mask vitamin B12 deficiency

• Symptoms: intestinal pain, nausea, vomiting

• Not enough folate• Macrocytic anemia• Elevated homocysteine• Neural tube defects


Vitamin B12

• Vitamin B12 is a water-soluble vitamin

• Functions of vitamin B12

• Coenzyme for DNA synthesis• Maintains myelin sheath of nerve fibers• Metabolism of amino acid homocysteine


Vitamin B12

• Factors that alter vitamin B12 digestion, absorption, and balance• Requires acidic environment (stomach) and

protein intrinsic factor for absorption • Stored in the liver

• Four levels of vitamin B12 deficiency

Vitamin B12 Absorption


Vitamin B12

• Recommended intake• RDA for adults is 2.4 µg/day

• Sources of vitamin B12

• Available exclusively from animal sources

• Vegan diet may obtain vitamin B12 from fortified foods, supplements, or injections


Vitamin B12

• Too much vitamin B12

• No known adverse effects

• Not enough vitamin B12

• Deficiency is rare, but associated with dietary insufficiency or reduced absorption

• Gastrointestinal and neurologic effects• Pernicious anemia (lack intrinsic factor)


Neural Tube Defects

• Folate is required for cell division and proper formation of the neural tube (develops into brain and spinal cord)

• Increased early need for folate • All women capable of becoming pregnant

should consume an additional 400 g of folate daily


Vascular Disease

• Folate and vitamin B12 are required for the breakdown of amino acid homocysteine

• Low folate and vitamin B12 intake may increase the level of homocysteine

• High homocysteine levels are associated with risk for vascular disease

• Adequate folate, vitamin B6, vitamin B12 may reduce risk for heart attack or stroke


Anemia

• Anemia (“without blood”)—low hemoglobin• Genetic (sickle cell anemia, thalassemia)

• Microcytic anemia: low iron or vitamin B6

• Macrocytic anemia: low vitamin B12 or folate

• Pernicious anemia: low vitamin B12


Immune System

• A healthy immune system • Protects the body from infectious diseases• Helps heal wounds• Guards against the development of cancers

• How does it function?• Nonspecific immune function • Specific immune function


Nonspecific Immune System

• Body’s primary defense against microbes, airborne particles, venom, ingested toxins

• Also called innate immunity • Intact skin and healthy mucous membranes• Stomach acid destroys food-borne bacteria• Inflammatory response causes discomfort,

loss of appetite, fatigue, and fever


Specific Immune System

• Directed against recognized antigens• Induces antibodies to destroy invader• Memory cells remain in circulation• Two main types of cells: B cells and T cells

• Acquiring specific immunity• Have disease or vaccinations (immunizations)• Maternal antibodies• Antiserum injection (snakebite)


Immune System

• Malfunction causes chronic inflammation and infection• Allergic reactions• Autoimmune response• Common in malnourished• Immune deficiency diseases


Nutrition

• A nourishing diet provides all the nutrients the immune system needs

• Single-nutrient subclinical deficiencies can cause subtle abnormalities in immunity

• Protein-energy malnutrition and severe micronutrient deficiencies reduce immune function


Protein-Energy Malnutrition

• Malnutrition increases the risk for infection• Infection depresses appetite and often causes

vomiting and diarrhea• Decreased appetite, vomiting, and diarrhea

cause malnutrition, which increases vulnerability to infection

• Decreased immunocompetence is a sensitive indicator of reduced nutritional status


Overnutrition/Obesity

• Increases incidence of infections• Delays wound healing• Poor antibody response to vaccination• Inflammatory state may increase asthma,

hypertension, cardiovascular disease, and type 2 diabetes among obese individuals


Essential Fatty Acids

• Essential fatty acids are precursors for signaling molecules eicosanoids

• Omega-6 fatty acids promote inflammatory response to help contain infection

• Omega-3 fatty acids diminish inflammation in blood vessels (prevent heart disease)


Vitamins and Minerals

• Vitamin A maintains mucosal surface • Vitamins C and E protect cell membrane from

reactive oxygen species• Zinc assists immune cell gene expression and

enzyme activation (B and T cell proliferation)


Vitamins and Minerals

• Copper: growth factor for immune cells• Iron deficiency impairs immune function • Selenium: • Coenzyme for glutathione peroxidase• Promotes B and T cell proliferation• Antibody production

• Excessive amounts can impair immunity

© 2011 pearson education, inc. 12 nutrients involved in blood health and immunity

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