Chapter 10
Nutrients Involved in Energy Metabolism and Blood Health
Vitamins and Metabolism
Vitamins and minerals
 Are required for proper metabolism
 Do not directly provide energy
 Are necessary for obtaining energy from the macronutrients
 Often function as coenzymes
Vitamins and Metabolism
Enzymes: a protein that accelerates the rate of a chemical reaction.
 Enzymes are required for all metabolic reactions
Coenzymes: a molecule that combines with an enzyme to activate it.
 Some metabolic reactions require coenzymes
B-complex Vitamins
The B-complex vitamins are especially important for energy metabolism.
The B-complex vitamins include
Thiamin (B1)
folate
riboflavin (B2)
cobalamin (B12)
niacin
pantothenic acid
Pyridoxine (B6)
biotin
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,
heart failure
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, yogurt, enriched bread and grain products,
organ meats.
 Ariboflavinosis: riboflavin deficiency; sore throat, swollen mucous membranes
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
B-complex Vitamins: Vitamin B6 (Pyridoxine)
 Group of six related compounds
 Part of a coenzyme for more than 100 enzymes, amino acid metabolism,
neurotransmitter, and 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
B-complex 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
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
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.
Anemia
Anemia means “without blood”; any condition of low hemoglobin levels.
There are many types and causes of anemia.
Macrocytic Anemia
 Caused by a severe folate deficiency
 Results in enlarged red blood cells carrying insufficient hemoglobin
 Shows common symptoms of anemia including weakness, fatigue, difficulty
concentrating, irritability, headache, shortness of breath
Vitamin B12 (Cobalamin)
 Part of coenzymes for blood formation
 Required for nerve functioning
 Required for homocysteine breakdown
 Found only in animal-based foods
 Deficiency results in anemia, low energy, fatigue, shortness of breath, and can lead
to pernicious anemia
Vitamin B12 (Cobalamin)
 Deficiency is due to insufficient intake or inability to absorb the vitamin
 Absorption requires: intrinsic factor and low stomach pH
 Lack of intrinsic factor production can occur
 Atrophic gastritis results in inadequate stomach acid production
 Vegans are at risk for deficiency
Vascular Disease and Homocysteine
Folate and vitamin B12 are required for the breakdown of the amino acid homocysteine.
Low folate, vitamin B12, and vitamin B6 intake may cause an increased level of
homocysteine.
High homocysteine levels are associated with greater risk of cardiovascular and
cerebrovascular disease.
Pernicious Anemia
 Pernicious means causing great harm or fatal
 Vitamin B12 deficiency
 Due to low acid production in the stomach or lack of gastric intrinsic factor
production
 Also occurs in people who consume very little vitamin B12 in their diet
 Symptoms are pale skin, reduced energy, fatigue, neurological symptoms
Pantothenic Acid
 Component of coenzymes for fatty acid metabolism
 Required for building new fatty acids
 Good sources: chicken, beef, egg yolk, potatoes, oat cereals, tomato products
 No toxicity from excess pantothenic acid
 Deficiency is very rare
Biotin
 Part of coenzymes involved in metabolism of carbohydrates, fat, and proteins
 Important for gluconeogenesis
 Biotin content has been determined for very few foods
 Deficiency symptoms include hair thinning, loss of hair color, red rash on face
 Deficiency is very rare
Choline
Choline is a vitamin-like substance.
 Assists in homocysteine metabolism
 Accelerates the synthesis of acetylcholine, a neurotransmitter
 Good sources: milk, liver, eggs, peanuts
 Deficiency can lead to fat accumulation in the liver
 Toxicity can result from supplements
Iodine
Iodine is a trace mineral.
 Critical for the synthesis of thyroid hormones
 Thyroid hormones regulate body temperature, growth, and resting metabolic rate
 Good sources: saltwater fish, shrimp, iodized salt, milk and dairy products
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
Chromium
Chromium is a trace mineral.
 Assists insulin as it transports glucose from the blood into the cells
 Plays a role in immune function and growth
 There is very little chromium in the body
 Good sources: mushrooms, prunes, dark chocolate, nuts, whole grains
 Chromium deficiency inhibits glucose absorption by body cells
Manganese
Manganese is a trace mineral.
 Coenzyme involved in energy metabolism
 Part of the antioxidant enzyme superoxide dismutase
 Good sources: whole-grain foods, brown rice, pineapple, pine nuts, okra, spinach
 Toxicity impairs the nervous system causing spasms and tremors
Sulfur
Sulfur is a major mineral.
 Component of thiamin and biotin
 Stabilizes protein structure
 Required for detoxification of alcohol and drugs by the liver
 Found in two amino acids
 Requirement for sulfur is met from the protein in our diets
What is the role of Blood in maintaining health?
Blood is the only fluid tissue in the body.
Functions
 Transport of oxygen and nutrients to cells
 Removal of wastes 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
Nutrients that maintain Blood health
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
 Deficiencies can result from diseases that disturb absorption of fats
 Newborns are given vitamin K at birth
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
 Is needed for effective immune function
 Iron is part of the antioxidant enzyme system
 Is required for nerve and muscle function
Iron can be stored in the body as ferritin or homosiderin.
 Storage is usually in the liver, bone marrow, intestinal mucosa, and spleen
Two types of iron are found in foods
 Heme iron—found in animal based foods and more absorbable
 Non-heme iron—not easily absorbed, iron not part of hemoglobin or myoglobin
Iron Recommended intake
 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
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
 Delayed treatment of iron toxicity can result in severe damage to the heart, central
nervous system, liver, kidneys
 Hemochromatosis—excessive iron absorption
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
Iron-Deficient Anemia
 Iron deficiency results in small red blood cells that do not carry enough
hemoglobin
 Symptoms are fatigue, pale skin, impaired work performance, depressed immune
function, impaired memory
Zinc
Zinc is a trace mineral.
Functions of zinc
 Cofactor for hemoglobin production
 Part of superoxide dismutase antioxidant enzyme system
 Development and function of immune system
 Growth
 Assists in energy metabolism
Zinc Recommended intake
 RDA is 8 mg/day for women
 11 mg/day for men
Sources of zinc
 Red meats, some seafood, whole grains, enriched grains and cereals
What if you consume too much zinc?
 Toxicity can occur from supplements
 Symptoms are intestinal pain, cramps, nausea, vomiting, loss of appetite
What if you don’t consume enough zinc?
 Deficiencies are uncommon in the United States
 Symptoms are growth retardation, diarrhea, delayed sexual maturation
Copper
Copper is a trace mineral.
Functions of copper
 Cofactor for energy metabolism
 Coenzyme that assists in collagen production
 Part of superoxide dismutase antioxidant enzyme system
 Required for iron transport
Copper Recommended intake
 RDA for adults is 900 µg/day
Sources of copper
 Organ meats, seafood, nuts, seeds, whole-grain foods
What if you consume too much copper?
 Toxicity in not well studied in humans
 Symptoms are intestinal pain, cramps, nausea, vomiting, liver damage
What if you don’t consume enough copper?
 Copper deficiency is rare
 Symptoms are anemia, reduced white blood cells, osteoporosis in children