lecture 12 nutrients involved in energy metabolism

NDD10103 PRINCIPLES OF HUMAN NUTRITION

Lecture 12: Nutrition Involved in Metabolism and Blood Health

DR. SHARIFAH WAJIHAH [email protected].

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Course Learning Outcomes• At the end of this lecture, the student should be able to:1. Describe how coenzymes enhance the activities of

enzymes.2. For each of the eight B-complex vitamins, describe their

primary functions and their food sources.3. Describe the association between folate, vitamin B12, and

vascular disease.4. Identify at least two minerals that function as coenzymes in

energy metabolism.5. Discuss the role that iron plays in oxygen transport.6. Distinguish between iron-deficiency anemia, pernicious

anemia, and macrocytic anemia.


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



• 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



Figure 10.1



Figure 10.2


B-complex Vitamins

• The B-complex vitamins are especially important for energy metabolism.

• The B-complex vitamins include-thiamin (B1) -folate-riboflavin (B2) -vitamin B12

-niacin -pantothenic acid-vitamin B6 -biotin


B-complex 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, heart failure


B-complex 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; sore throat, swollen mucous membranes


B-complex 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


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.


Spina Bifida


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


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


B-complex Vitamins: 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


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


B-complex Vitamins: 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

• 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.


Vascular Disease and Homocysteine

Figure 10.8


B-complex Vitamins: 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


B-complex Vitamins: 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


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


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


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 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


Blood

Figure 10.12


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


Iron

• 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


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– Delayed treatment of iron toxicity can result in

severe damage to the heart, central nervous system, liver, kidneys

– Hemochromatosis—excessive iron absorption


Iron

• 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

Figure 10.15


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


Zinc

• 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


Copper

• 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


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lecture 12 nutrients involved in energy metabolism

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