Transcript Ch10EnergyMetab

C HAPTER
10
Nutrients Involved in
Energy Metabolism
and Blood Health
and In Depth
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Vitamins and Metabolism
Vitamins and minerals
 Are required for proper metabolism
 Do not directly provide energy
 Are necessary for obtaining energy from
macronutrients
 Often function as coenzymes
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Vitamins and Metabolism
Enzyme: a protein that accelerates the rate of a
chemical reaction
 Enzymes are required for all metabolic reactions
Coenzyme: a molecule that combines with an
enzyme to activate it
 Some metabolic reactions require coenzymes
PLAY
Energy Metabolism
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Vitamins and Metabolism
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Vitamins and Metabolism
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B-Vitamins
The B-vitamins are especially important for energy
metabolism
The B-vitamins include:
thiamin (B1)
riboflavin (B2)
niacin
vitamin B6
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folate
vitamin B12
pantothenic acid
biotin
B-Vitamins: Thiamin (Vitamin B1)
 Coenzyme thiamin pyrophosphate is required for
carbohydrate metabolism
 Coenzyme for the metabolism of some fatty acids
 Enriched foods, whole grains, and pork are good
sources
 Beriberi: deficiency of thiamin resulting in muscle
wasting and nerve damage, and heart failure
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B-Vitamins: Riboflavin (Vitamin B2)
 Part of coenzymes involved in oxidation–reduction
reactions
 Part of the antioxidant enzyme glutathione
peroxidase
 Milk is a good source of riboflavin
 Ariboflavinosis: riboflavin deficiency that causes
sore throat and swollen mucous membranes
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B-Vitamins: Niacin
 Nicotinamide and nicotinic acid
 Coenzyme assists with the metabolism of
carbohydrates and fatty acids
 Good sources: meat, fish, poultry, enriched bread
products
 Toxicity can result from supplements
 Pellagra: severe niacin deficiency
 4 Ds: dermatitis, diarrhea, dementia, and death
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B-Vitamins: Vitamin B6 (Pyridoxine)
 Group of six related compounds
 Part of a coenzyme for more than 100 enzymes,
assists in amino acid metabolism, neurotransmitter,
and assists in heme synthesis
 Good sources: enriched cereals, meat, fish, poultry,
starchy vegetables
 Toxicity from supplements can result in nerve
damage and skin lesions
 Deficiency: anemia, elevated levels of
homocysteine
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B-Vitamins: Folate
 Involved in DNA synthesis, amino acid
metabolism, red blood cell synthesis
 Critical for cell division of very early embryos
 Good sources: ready-to-eat cereals, enriched bread
products
 Toxicity can mask vitamin B12 deficiency
 Deficiency: macrocytic anemia
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Folate Deficiency: Neural Tube Defects
A woman’s need for folate dramatically increases
during pregnancy
Folate is required for cell division and proper
formation of the neural tube
 The neural tube develops into the brain and spinal
cord
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Folate Deficiency: Neural Tube Defects
The increased need for folate is critical very early
(first 4 weeks) in pregnancy, frequently before a
woman knows she is pregnant
All women capable of becoming pregnant should
consume an extra 400 µg/day of folate
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Spina Bifida
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Folate Deficiency: Anemia
Anemia means “without blood”; any condition of
low hemoglobin levels
There are many types and causes of anemia
Anemia “without blood” can be caused by a severe
folate deficiency
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B-Vitamins: Vitamin B12 (Cobalamin)
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Part of coenzymes for blood formation
Found only in animal-based foods
Deficiency can lead to pernicious anemia
Vegans are at risk for deficiency
Also occurs in people who consume very little
vitamin B12 in their diet
 Symptoms are pale skin, reduced energy, fatigue,
and neurological symptoms
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B-Vitamins: Pantothenic Acid
 Component of coenzymes for fatty acid metabolism
 Deficiency is very rare
 Biotin:
 Part of coenzymes involved in the metabolism of
carbohydrates, fat, and proteins
 Deficiency is very rare
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Iodine
Iodine is a trace mineral
 Critical for the synthesis of thyroid hormones
 Thyroid hormones regulate body temperature,
growth, and resting metabolic rate
 Hypo, hyperthyroidism: Hashimoto’s, Grave’s
disease
 Good sources: saltwater fish, shrimp, iodized salt,
milk and dairy products
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Iodine
Excess iodine
 Blocks synthesis of thyroid hormones
 Thyroid tries to make more hormones
 Results in goiter: enlarged thyroid
Iodine deficiency
 Results in hypothyroidism and goiter
 Cretinism: mental retardation from iodine
deficiency during embryonic development
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Chromium and Manganese
Chromium is a trace mineral
 Assists insulin as it transports glucose from the
blood into the cells
 Good sources: mushrooms, prunes, dark chocolate,
nuts, whole grains
Manganese is a trace mineral
 Coenzyme involved in energy metabolism
 Good sources: whole-grain foods, brown rice,
pineapple, pine nuts, okra, spinach
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Blood: Iron, Vit. K, Zinc & Copper
Blood is the only fluid tissue in the body
Functions
 Transport of oxygen and nutrients to cells
 Removal of waste products from cells
Components of Blood
 Erythrocytes: red blood cells
 Transport oxygen through the body
 Leukocytes: white blood cells of the immune system
 Platelets: cell fragments that assist in blood clotting
 Plasma: the fluid portion of the blood
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Components of Blood
 Erythrocytes: red blood cells
 Transport oxygen through the body
 Leukocytes: white blood cells of the immune
system
 Platelets: cell fragments that assist in blood clotting
 Plasma: the fluid portion of the blood
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Components of Blood
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Vitamin K
Vitamin K is a fat-soluble vitamin
 Coenzyme for the synthesis of proteins involved in
blood clotting
 Healthful intestinal bacteria produce some
vitamin K
 Good sources: green leafy vegetables
 Newborns are given vitamin K at birth
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Iron
Iron is a trace mineral
Functions of iron
 A component of the protein hemoglobin, which
carries oxygen in erythrocytes
 A component of myoglobin, which carries oxygen
in muscle cells
 A coenzyme involved in the metabolism of
carbohydrates, fats, and proteins
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Iron
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Iron
Recommended intake
 Recommended Dietary Allowance (RDA) varies
based on age and gender
 8 mg/day for adult men
 27 mg/day for pregnant women
Sources of iron
 Meat, poultry, fish, clams, oysters, enriched cereals
and breads
 Meat factor and vitamin C enhance absorption
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Iron
What if you consume too much iron?
 Iron overdose is the most common cause of poisoning
deaths in children
 Toxicity symptoms: nausea, vomiting, diarrhea,
dizziness, confusion
 What if you don’t consume enough iron?
 Iron deficiency is the most common nutrient deficiency
in the world
 High-risk people include infants, young children,
preadolescent girls, premenopausal women, and
pregnant women
 There are three stages of iron deficiency
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Iron
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Zinc and Copper: trace minerals
Functions of zinc:
 Cofactor for hemoglobin production
 Assists in energy metabolism, immune system and
growth
Sources of zinc
 Red meats, some seafood, whole grains, enriched
grains and cereals
Functions of copper
 Cofactor for energy metabolism
 Coenzyme that assists in collagen production
Sources of copper
 Organ meats, seafood, nuts, seeds, whole-grain foods
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In Depth: Dietary Supplements
Dietary supplements are defined by the FDA as
products taken by mouth containing a dietary
ingredient intended to supplement the diet
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In Depth: Dietary Supplements
May contain:
Vitamins
Minerals
Herbs or other botanicals
Amino acids
Enzymes
Tissues from animal organs or glands
…or a concentrate, a metabolite, a constituent,
or an extract
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Dietary Supplement Regulation
 Categorized generally as foods, not drugs
 Regulation is less rigorous than for drugs
 FDA regulation of supplements marketing is
currently in flux
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What Consumers Should Know
 FDA approval is not needed for marketing
 Manufacturers are solely responsible for safety
 Sellers are not required to show evidence of
safety
 There are no federal guidelines to ensure purity,
safety, or composition
 No rules limit serving sizes
 Once a supplement is marketed, the FDA must
prove it is unsafe for it to be removed from
stores
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Avoiding Web-Based Supplements Fraud
Critically assess the Web site:
 What is its purpose?
 Is information accurate?
 Does it use reputable references?
 Who owns or sponsors the site?
 Who wrote the information?
 Is the information current?
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Herbal Supplements
 An herb (or botanical) is a plant or plant part
used for its scent, flavor, and/or therapeutic
properties
 Consult your healthcare provider before using
herbal supplements
 Herbs may cause serious medical problems if
used in large amounts
 Avoid using herbs when pregnant or nursing,
unless you have consulted a doctor
 Active ingredients in many herbs and herbal
supplements are not known
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Should You Take Supplements?
 Many people do not need supplements
 Supplements are not substitutes for whole foods
 Some individuals who may benefit from
supplements include:
 Vegans
 Athletes
 Infants and children
 Pregnant teens and pregnant women
 Elderly people
 Convalescents
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