Vitamins Lecture 7

Vitamins: Lecture 7

• Vitamins are essential, non-caloric organic nutrients, required in small amounts.
• Vitamins do not supply energy.
• They cannot be synthesized by the body. They must be obtained from outside sources such as food, bacteria in the rumen, or sunlight.
• Unlike carbohydrates, proteins, and fats, vitamins are individual units, not linked together.
• Vitamins are crucial for growth, maintenance, reproduction, and lactation.

Learning Objectives

• Identify the meaning of vitamins.
• Compare fat-soluble vitamins with water-soluble vitamins.
• Discuss the roles, food sources, function, and consequences of deficiency and toxicity of fat-soluble vitamins.
• Discuss the roles, food sources, function, and consequences of deficiency and toxicity of water-soluble vitamins.

Classification of Vitamins

• Fat-soluble vitamins: Vitamins A, D, E, and K.
• Water-soluble vitamins: Vitamin C and B vitamins (Thiamin, Riboflavin, Niacin, Biotin, Pantothenic acid, Vitamin B6, Folate, and Vitamin B12).

Characteristics of Fat-Soluble and Water-Soluble Vitamins

Fat-Soluble Vitamins (A, D, E, K)

• Fat-soluble vitamins play diverse roles in the body.
• Vitamins A and D act as hormones.
• Vitamin E protects tissues from oxidative damage.
• Vitamin K is needed for blood clotting and bone health.

Vitamin A

• Vitamin A is a group of similar compounds called retinoids.
• There are three forms: retinol (most active form), retinal, and retinoic acid.
• About 10% of plant-derived carotenoids (like beta-carotene) can be converted into retinoids.
• Carotenoids give plants their yellow, orange, and red colors.
• Functions: Vision(pigment generation in the retina), maintaining coverings and linings of the eyes, cell growth, immune cell development, and healthy skin.
• Recommendation/Sources: For men: 900 mcg/day. For women: 700 mcg/day (increased during lactation). Animal sources (eggs, meat, cheese, milk, liver), plant sources (carrots, sweet potatoes, pink grapefruit, apricots, broccoli, spinach, pumpkin).

Vitamin A Deficiency

• Night blindness, exophthalmia
• Decreased resistance to infections
• Extremely dry skin, hair, or nails
• Anemia
• Retarded growth in children.

Vitamin A Toxicity

• Single large doses of supplements, eating excessive amounts of liver.
• Symptoms include dry, itchy skin, headaches, fatigue, hair loss, blurred vision, loss of appetite, swelling of the brain, joint pain, and skin coloration. In severe cases, liver damage and coma may occur.
• Excessive vitamin A during pregnancy can cause birth defects.

Vitamin E

• Alpha-tocopherol is the only form recognized for human needs.
• Functions: Antioxidant, stops free radical formation, discourages cancer development, crucial for nerve development, promotes growth, inhibits blood clotting, and aids wound healing. Boosts the immune system.
• Recommendations/Sources: 15 milligrams daily for adults. Sources: wheat germ oil, vegetable oils, nuts, seeds, whole grains, egg yolk, leafy green vegetables. Vitamin E is easily destroyed by heat.

Vitamin E Deficiency

• Insufficient levels are rare, but likely with extremely low-fat diets for years.
• People at high risk include those with malabsorption disorders like Crohn's disease or cystic fibrosis and premature babies.
• Symptoms: red blood cell breakage, nerve damage, muscle coordination loss, impaired vision and speech.

Vitamin E Toxicity

• More than 1000 mg daily can be toxic. It can augment the effect of anti-clotting medication.

Vitamin K

• Produced by bacteria in the large intestine.
• Function: Promotes blood clotting and bone formation.
• Deficiency Symptoms: Hemorrhaging (rare, but seen in infants after prolonged antibiotic therapy, and in patients with decreased bile production).

Vitamin K Toxicity

• None known.

Vitamin K Sources

• Bacterial synthesis in the digestive tract, Milk, Leafy green vegetables, cabbage-type vegetables
• Recommendation for Men: 120 mcg/day, for Women: 90 mcg/day.

Vitamin D

• Synthesized in the body with sunlight exposure. The skin synthesizes vitamin D when exposed to sunlight.
• Vitamin D is not an essential nutrient.
• Factors that decrease synthesis: Season (long winter), wearing sunscreen, skin color (darker skin needs more time), time of day (vitamin D3 synthesis increases in the morning), age (older people), clothing (full clothing that covers the skin), using sunscreen.
• Function: Essential for the proper utilization of calcium and phosphorus to produce normal, healthy bones. Plays a role in muscle function and the immune system. May help prevent colon, prostate, and breast cancers, and might help in preventing and treating diabetes, heart disease, and multiple sclerosis.
• Deficiency Diseases: Rickets (children), Osteomalacia (adults)
• Deficiency Symptoms: Rickets (bowed legs), Osteomalacia (soft, flexible, weak, and deformed bones), loss of appetite, nausea, vomiting, frequent urination, fatigue, back pain, and irregular heartbeat.
• Source/Recommendation: Synthesized in the body with sunlight. People ages 1-70 years old need 15 micrograms daily. 71 and older need 20 micrograms daily. Fortified milk, margarine, butter, cereals, beef, egg yolk, liver, fatty fish.

Water-Soluble Vitamins

• Include Vitamin C and the B-complex vitamins.

Vitamin C (Ascorbic Acid)

• Protects the body from free radicals.
• Helps form connective tissue (collagen).
• Aids in wound healing.
• Helps the body absorb iron from plant sources.
• Helps maintain healthy gums.
• Helps fight infections.
• Aids in the prevention of heart disease.

Vitamin C Deficiency

• Scurvy (bleeding gums, loosened/sore teeth, swollen ankles and wrists.)
• Fatigue and joint pain.
• Reduced resistance to colds and infections.
• Slow healing of wounds and fractured bones.
• Anemia.

Vitamin C Toxicity

• Symptoms potentially include nausea, abdominal cramps, diarrhea, headache, fatigue, insomnia, rashes, and urinary tract problems/kidney stones (over 1000mg dose).

Vitamin C Sources

• Citrus fruits (oranges, grapefruits, lemons, limes)
• Cabbage-type vegetables, dark green vegetables (broccoli)
• Strawberries, berries, cantaloupe, melons, papayas, mangoes, potatoes, tomatoes, guava
• Recommendation for Men: 90mg, Women: 75mg, Smokers: +35mg daily. Adults: up to 2000mg daily.

B Complex Vitamins (Thiamin, Riboflavin, Niacin, Biotin, Pantothenic acid, Vitamin B6, Folate, Vitamin B12).

• Aid in metabolism of carbs, lipids, & amino acids, and help the body use this energy.
• Part of coenzymes that combine with enzymes and activate them.
• Examples discussed included Thiamin and Riboflavin.

Vitamin B1 (Thiamine)

• Important in glucose metabolism.
• Acts as a cofactor for enzymes.
• Breaks down glucose.
• Involved in neurotransmitter synthesis (RNA, DNA, ATP).
• Sources: Whole-grain, fortified, or enriched grain products. Moderate amounts in most nutritious foods.
• Toxicity: None reported.

Vitamin B1 Deficiency Disease: Beriberi and Wernicke-Korsakoff Syndrome

Vitamin B2 (Riboflavin)

• Essential component of flavoproteins and coenzymes in many metabolic pathways for carbohydrates, lipids, and proteins.
• Gives a bright yellow color to riboflavin.
• Sources: Milk and dairy products (yogurt, cheese), enriched or whole grains, liver.
• Deficiency: Cracks and redness at the corners of the mouth, sore throat, hypersensitivity to light, itching, burning eyes, dry, scaly skin.
• Recommendation Men: 1.3mg/day, Women: 1.1mg/day

Vitamin B3 (Niacin)

• Participates in the energy metabolism of all cells.
• Amino acid tryptophan is converted into niacin in the body.
• Sources: Abundant in plants, especially mature grains.
• Deficiency Disease: Pellagra (4Ds: diarrhea, dermatitis, dementia, death).

Vitamin B6 (Pyridoxine)

• Part of coenzyme needed in amino acid/fatty acid metabolism.
• Essential for conversion of methionine to cysteine, tryptophan to niacin/serotonin.
• Helps make hemoglobin.
• Assists in releasing stored glucose, glycogen.
• Develops the fetus’ brain and nervous system.
• Deficiency Symptoms: Weakness, depression, confusion, irritability, seizures, insomnia, greasy dermatitis.
• Sources: Meat, fish, poultry, starchy vegetables/fruits, potatoes and leafy green vegetables

Folate (B9) (Folic Acid)

• Function: Required for the synthesis of RNA and DNA. Works with vitamin B12 to form hemoglobin. Essential in amino acid metabolism (methionine) . Helps prevent neural tube defects (spina bifida).
• Deficiencies: Anemia, smooth, red tongue, mental confusion, weakness, fatigue, irritability, headache.
• Sources: Fortified grains, leafy green vegetables, legumes, seeds, liver,
• Recommendations: DRI: 400 micrograms/day.

Vitamin B12 (Cobalamin)

• Contains cobalt (metal ion).

• In order for absorption, the stomach, pancreas, and small intestine must function properly (intrinsic factor is required).

• Functions: Needed in new cell synthesis, maintains nerve cells, breaks down fatty acids and amino acids, essential for hemoglobin synthesis, helps convert folate to active form.

• Deficiency Diseases: Pernicious anemia (large immature red blood cells).

• Deficiency Symptoms include anemia, fatigue, paralysis, nerve damage (in the fetus)

• Sources Animal products (meat, poultry, fish, shellfish, milk, cheese, eggs), fortified cereals.

• Toxicity None reported

General Conclusion

• The slides provide a comprehensive overview of various vitamins, their functions, sources, deficiency diseases, and recommended daily intakes. This material can be used for study and note-taking.