Download Chapter 12: Nutrients Involved in Blood Health and Immunity

Chapter 12 Lecture
Chapter 12:
Nutrients
Involved in Blood
Health and
Immunity
© 2017 Pearson Education, Inc.
Blood
• Functions
• Transports nutrients and oxygen to cells
• Removes waste products generated from
metabolism
• Immune function (white blood cells)
• Mechanism for heat transfer
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Micronutrients That Maintain Healthy Blood
• Minerals
• Iron
• Zinc
• Copper
• Vitamins
• Vitamin K
• Vitamin B6
• Folate
• Vitamin B12
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Iron
• Iron is a trace mineral
• Component of oxygen-carrying hemoglobin in
erythrocytes and myoglobin in muscles
• Heme groups depend on iron to carry oxygen in
hemoglobin
• Component of cytochromes, electron carriers
within the metabolic pathways for energy
production from macronutrients
• Part of antioxidant enzyme system
• DNA synthesis and cognitive development
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Iron
• Two types of iron in foods
• Heme iron: part of hemoglobin and
myoglobin, found only in animal-based foods
and more absorbable
• Non-heme iron: found in both plant and
animals, not as easily absorbed
• Majority of iron in food (90–95%) is nonheme
iron
• Iron in animal-based food is 50–60% heme
iron
© 2017 Pearson Education, Inc.
Iron (cont.)
• Factors that enhance iron absorption
• Meat factor
• Stomach acids
• Vitamin C
© 2017 Pearson Education, Inc.
Iron (cont.)
• 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 approx.
1–10%, vs. typical Western diet's absorption of
14–18%
© 2017 Pearson Education, Inc.
Iron (cont.)
• Iron transport
• Ferroportin: transports iron and regulates
intestinal absorption and release
• Transferrin: iron-transport protein in blood
• Receptors on cells transport iron into cells
• Iron storage
• Ferritin (primary) and hemosiderin (overflow)
help meet iron needs
• Liver, bone marrow, and spleen
© 2017 Pearson Education, Inc.
Regulation of Total Body Iron
• Absorption depends on:
• Amount consumed
• Amount needed
• Dietary factors affecting absorption
• Losses
• Major loss in turnover of gut enterocytes
• Lost in feces, menses, blood donations
• Storage and recycling
• As cells break down, iron is recycled and
returned to body's iron pool
© 2017 Pearson Education, Inc.
Iron (cont.)
• 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
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
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, chelation drugs
© 2017 Pearson Education, Inc.
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)
© 2017 Pearson Education, Inc.
Stages of Iron Deficiency
• Iron depletion (stage I) is caused by a
decrease in iron stores
• Iron-deficiency erythropoiesis (stage II)
occurs with decreased iron transport
• Iron-deficiency anemia (stage III) results in
reduced normal, healthy red blood cell
production, decreased size, inadequate
hemoglobin
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Zinc
• Zinc is a trace mineral
• Functions of zinc
• Component of enzymes (heme synthesis)
• Maintain structural integrity and shape of
proteins (zinc fingers)
• Assist in regulating gene expression
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
Zinc (cont.)
• Metallothionein regulates absorption and
release
• 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
© 2017 Pearson Education, Inc.
Zinc (cont.)
• RDA: 8 mg/day for women, 11 mg/day for men
• Sources of zinc
• Red meats, some seafood, whole grains,
enriched grains and cereals
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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)
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
Copper
• Recommended intake
• RDA for adults is 900 µg/day
• Sources of copper
• Organ meats, seafood, nuts, seeds, wholegrain foods
© 2017 Pearson Education, Inc.
© 2017 Pearson Education, Inc.
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)
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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 and
synthesis
• Impaired dietary fat absorption
• Excessive broad-spectrum antibiotics
© 2017 Pearson Education, Inc.
Vitamin K
• Recommended intake
• AI for adults is 90 µg/day for women;120
µg/day for men
• No established UL at this time
• Sources of vitamin K
• Green leafy vegetables, such as collard
greens, kale, spinach, cabbage
• Soybean and canola oils
© 2017 Pearson Education, Inc.
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)
© 2017 Pearson Education, Inc.
Vitamin B6
• Essential for heme synthesis
• Integral part of the heme complex
• RDA for adults is 1.3 mg/day, 1.5 mg/day for
older women and 1.7 mg/day for older men; UL
is 100 mg/d
© 2017 Pearson Education, Inc.
Vitamin B6
• Good sources include meats, poultry, fish, soybased foods, cereals, and starchy vegetables
• Deficiency can cause microcytic hypochromic
anemia and impairs protein metabolism
• Toxicity with high-dose supplements, affecting
nerves
© 2017 Pearson Education, Inc.
Folate
• One of the B vitamins
• Folate used for all forms of food folate with
biological function, folic acid in supplements,
enriched and fortified foods
• Functions of folate (coenzyme)
• DNA and amino acid synthesis
• Cellular division and differentiation
• Functions with B12 and B6 metabolism
© 2017 Pearson Education, Inc.
Folate
• Recommended intake
• RDA : 400 µg/day adults, 600 µg/day during
pregnancy
• Sources of folate
• Fortification to minimize birth defects (neural
tube defects): enriched breads, flours, pasta,
grain products
• Liver, spinach, lentils, oatmeal, asparagus
© 2017 Pearson Education, Inc.
Folate
• Four states of folate deficiency similar to iron:
1. Negative folate balance (stage I)
2. Folate depletion (stage II)
3. Folate deficiency erythropoiesis (stage III)
4. Folate deficiency anemia (stage IV)
© 2017 Pearson Education, Inc.
Folate
• Macrocytic anemias are larger than normal red
blood cells that inhibit adequate oxygen
transport
• Symptoms (similar to microcytic anemia)
include fatigue, irritability, difficulty
concentrating, headaches, shortness of
breath, reduced capacity for work
• Similar symptoms can result from vitamin B12
deficiency, so it's important to distinguish the
cause
© 2017 Pearson Education, Inc.
Vitamin B12
• Functions
• Coenzyme for DNA synthesis
• Regeneration of folic acid
• Alterations in status mimic those seen with
iron and folate
© 2017 Pearson Education, Inc.
Vitamin B12
• Recommended intake
• RDA for adults is 2.4 µg/day
• Sources of vitamin B12
• Found primarily in dairy products, eggs,
meats, poultry, fish, and shellfish (animal
sources)
• Vegan diet may obtain vitamin B12 from
fortified foods, supplements, or injections
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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
(destroyed myelin sheaths)
• Pernicious anemia (macrocytic) results in
reduced intrinsic factor production
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
• A macrophage is a type of nonspecific immune
cell. The one shown here is about to engulf an
invading microbe.
© 2017 Pearson Education, Inc.
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)
© 2017 Pearson Education, Inc.
Immune System
• Malfunction causes chronic inflammation and
infection
• Allergic reactions
• Autoimmune response
• Common in malnourished
• Immune deficiency diseases
© 2017 Pearson Education, Inc.
Nutrition and the Immune System
• 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
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
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
© 2017 Pearson Education, Inc.
Essential Fatty Acids
• Essential fatty acids are precursors for signaling
molecules eicosanoids
• Supplementation with EPA and DHA reduces
inflammation and may treat chronic inflammatory
conditions like rheumatoid arthritis, inflammatory
bowel disease, and cardiovascular disease
© 2017 Pearson Education, Inc.
Vitamins and Minerals
• Vitamin A maintains mucosal surface
• Vitamins C and E protect cell membrane from
reactive oxygen species
• Zinc important for immune function, gene
expression and enzyme activation (B and T cell
proliferation)
© 2017 Pearson Education, Inc.
Vitamins and Minerals (cont.)
• Selenium:
• Coenzyme for glutathione peroxidase
• Promotes B and T cell proliferation
• Antibody production
• Iron and copper:
• Part of superoxide catalase and dismutase
• Deficiencies reduce immune response (B and
T cell function)
• Excessive iron can impair immunity
© 2017 Pearson Education, Inc.
Infections Alter Nutrient Status
• Reduced food intake: illness/infection reduces
appetite and overall energy intake
• Increased nutrient loss (diarrhea, vomiting,
inflammation)
• Increased resting metabolic rate with fever
• Redistribution of energy and nutrients to
enhance the immune response
© 2017 Pearson Education, Inc.