Vitamins Lecture 7

Vitamins - Lecture 7

• Vitamins are essential, noncaloric organic nutrients, required in small amounts.
• They cannot be synthesized by the body; they must be obtained from outside sources such as diet, bacteria, or the sun.
• Vitamins are not linked together like carbohydrates, proteins, and fats. Instead, they are individual units.
• They are necessary for growth, maintenance, reproduction, and lactation.
• Vitamins are classified as either fat-soluble or water-soluble.

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: A, D, E, K
• Water-soluble vitamins: C and B complex

Fat-Soluble Vitamins

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

Vitamin A

• Vitamin A is a group of similar compounds called retinoids.
• There are three forms of vitamin A: retinol, retinal, and retinoic acid.
• About 10 percent of plant-derived carotenoids (including beta-carotene) can be converted into retinoids.
• Carotenoids (yellow, orange, and red pigments in plants) are converted to vitamin A.

Functions of Vitamin A

• Vision: Retinol generates pigments for the retina and maintains the coverings and linings of the eyes.
• Reproduction: Required for cell growth and division and the development of epithelial cells, bones, and teeth. It also plays a role in gene expression.
• Skin health: Promotes healthy skin.

Vitamin A Recommendation and Sources

• The daily recommended intake of vitamin A varies based on body weight and lactation status.
• Animal sources: eggs, meat, cheese, milk, liver, and kidney
• Plant sources: carrots, sweet potatoes, pink grapefruit, apricots, broccoli, spinach, and pumpkin. The body converts all dietary sources of vitamin A into retinol.

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 or excessive intake from liver consumption can cause toxicity.
• Symptoms: dry, itchy skin, headaches, fatigue, hair loss, blurred vision, loss of appetite, swelling of the brain, joint pain, and skin discoloration.
• Severe cases can lead to liver damage and coma. Excess consumption during pregnancy can cause heart, spinal cord, and fetal tissue damage.

Vitamin E

• Alpha-tocopherol is the only form recognized by the body to meet human requirements.
• Functions: antioxidant, prevents free radical damage, stops some types of cancer formation, promotes nerve development, growth and development, helps in wound healing, and a boost to the immune system.

Vitamin E Recommendation and Sources

• Recommendation for adults : 15 milligrams per day.
• Sources: wheat germ oil, vegetable oils, nuts, seeds, whole grains, egg yolk, and leafy green vegetables.
• Vitamin E is easily destroyed by heat.

Vitamin E Deficiency

• Insufficient vitamin E levels are rare but possible in diets extremely low in fat.
• People at higher risk: malabsorption disorders (like Crohn's or cystic fibrosis) and premature babies
• Deficiency symptoms: red blood cell breakage, nerve damage, loss of muscle coordination, and impaired vision and speech.

Vitamin E Toxicity

• Toxicity is unlikely but possible if taking very high doses from supplements; 1000 milligrams (mg)/day.
• It may increase 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 in infants after prolonged antibiotic therapy, and in patients with decreased bile production).

Vitamin K Recommendation and Sources

• Recommendation: men 120 micrograms a day, women 90 micrograms a day
• Sources: bacterial synthesis in digestive tract, milk, leafy green vegetables, and cabbage-type vegetables.

Vitamin D

• Synthesized in the body when exposed to sunlight.
• Vitamin D is not an essential nutrient.
• Factors decreasing synthesis: long winter, wearing sunscreen, skin color, age, clothing, and sunscreen use.
• 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, might help prevent and treat certain cancers, diabetes, heart disease and multiple sclerosis.

Vitamin D Deficiency

• Rickets in children (bowed legs).
• Osteomalacia in adults (soft, flexible, weak, and deformed bones).

Vitamin D Recommendation and Sources

• Ages 1–70 need 15 micrograms daily.
• Ages 71 and older need 20 micrograms daily.
• Sources: exposure to sunlight, fortified milk, margarine, butter, cereals, beef, egg yolk, and fatty fish.

Water-Soluble Vitamins (Vitamin C)

• Function: protects against free radicals, forms connective tissue (collagen) for bones, muscles and tissues, wound healing, aids in iron absorption from plant sources, helps to maintain a healthy immune system, and prevents heart disease
• Deficiency symptoms: scurvy, fatigue, and joint pain, reduced resistance to colds and infections, slow healing of wounds and fractured bones, anemia

Vitamin C Recommendation and Sources

• Recommendation: Men: 90 mg/day, Women 75 mg/day, Smoker : +35 mg/day; Adults: 2,000 mg/day
• Sources : Citrus fruits (oranges, grapefruits, lemons, limes), cabbage-type vegetables, Dark green vegetables (such as broccoli), strawberries and other berries, cantaloupe, melons, papayas, mangoes, potatoes, tomatoes, and guava

B Complex

• Thiamin (B1), Riboflavin (B2), Niacin (B3), Folate (B9), B6, B12, Biotin (B7), and Pantothenic acid.
• Function: aid in energy metabolism of carbohydrates, lipids, and amino acids. Also, part of coenzymes that combines with an enzyme to activate it.

Thiamin (B1)

• Function: important for glucose metabolism, acts as a cofactor for enzymes that break down glucose, plays a role in neurotransmitter synthesis, and is required for RNA, DNA, and ATP synthesis
• Sources: Whole-grain, fortified, or enriched grain products; Moderate amounts in other nutritious foods.
• Toxicity symptoms: none reported

Riboflavin (B2)

• Function: important component of flavoproteins which are coenzymes involved in carbohydrate, lipid, and protein metabolism.
• Source: Milk and dairy products, enriched or whole grains, liver.
• Deficiency: Cracks and redness at the corner of the mouth, sore throat, hypersensitivity to light, itching and burning in eyes, and dry, scaly skin.

Niacin (B3)

• Function: like thiamin and riboflavin it participates in energy metabolism of every cell and uses the amino acid tryptophan.
• Source: Meat, fish, poultry, starchy vegetables, fruits, potatoes, and leafy green vegetables.
• Foods high in it: broccoli, peanuts, chicken, mushrooms, bell peppers, and kidney beans
• Pellagra, the deficiency disease, symptoms: diarrhea, dermatitis, dementia, and death.

Vitamin B6 (Pyridoxine)

• Function: Part of coenzyme needed in amino acid & fatty acid metabolism, helps convert methionine into cysteine, and converts tryptophan to niacin and serotonin, helps to make hemoglobin, Assists in releasing stored glucose, and develops the brain and nervous system of a fetus.

Vitamin B6 Deficiency Symptoms

• Symptoms: Weakness, depression, confusion, irritability, convulsions, insomnia, greasy dermatitis (skin appears greasy and flaky).

Vitamin B6 Food Sources:

• Meat, fish, and poultry (protein-rich foods)
• Starchy vegetables
• Leafy green vegetables

Folate (B9) / Folic Acid

• Function: required for forming RNA & DNA, supports hemoglobin production, is a coenzyme for the synthesis of methionine.
• Important to prevent neural tube defects.
• Deficiency: anemia (large-cell type), smooth, red tongue, mental confusion, weakness, fatigue, irritability, and headache.

Folate (B9) / Folic Acid Food Sources

• Fortified grains, leafy green vegetables, legumes, seeds, and liver

Folate (B9) / Folic Acid Recommendations

• 400 micrograms per day

Vitamin B12 (Cobalamin)

• Function: Part of coenzymes used in new cell synthesis, maintains nerve cells, helps break down fatty acids, and critical for hemoglobin synthesis. Also converts folate to an active form.
• Obtaining it: Stomach produces intrinsic factor to absorb vitamin B12; needed by the pancreas and small intestine, otherwise, it lacks proper absorption.
• Deficiency: Pernicious anemia, large and immature red blood cells.
• Symptoms: Anemia, fatigue, paralysis, nerve damage in the fetus.

B12 Food Sources

• Animal products: meat, poultry, fish, shellfish, milk, cheese, eggs.
• Fortified cereals

Toxicity Symptoms

• None reported for B12

Note:

• All presentation data is likely intended for medical use, follow your doctor's instructions at all times.

Explore the essential role of vitamins in human health in this quiz based on Lecture 7. Learn about the differences between fat-soluble and water-soluble vitamins, their sources, functions, and the consequences of their deficiencies and toxicities. Test your knowledge on vitamins A, D, E, K, C, and the B complex.