Vitamins and Nutritional Deficiencies Quiz

Vitamins

• Vitamins are complex organic compounds
• The body does not make enough vitamins to maintain good health
• Vitamins occur naturally in common foods
• A deficiency disorder occurs when a vitamin is missing from the diet
• Vitamins restore good health when the missing substance is supplied

Learning Outcomes

• Classify vitamins as fat-soluble or water-soluble
• Discuss methods to conserve vitamin content or increase bioavailability
• Explain the function of antioxidants and define enrichment/fortification
• List the four fat-soluble vitamins and identify dietary sources
• Discuss major functions of each fat-soluble vitamin
• Identify health problems associated with excesses and deficiencies of fat-soluble vitamins
• List water-soluble vitamins and identify dietary sources
• Discuss major functions of each water-soluble vitamin
• Identify health problems associated with excesses and deficiencies of water-soluble vitamins
• Identify health problems from excesses and deficiencies of vitamin B12, vitamin C, pantothenic acid, and biotin
• Evaluate vitamin supplements, considering health benefits and hazards
• Identify foods that may increase cancer risk
• Discuss steps to reduce cancer risk

Vitamins: Basic Concepts

• Vitamins are complex organic compounds
• The body does not produce enough to maintain good health
• Vitamins occur naturally in common foods
• A deficiency in vitamins can cause deficiency disorders
• Supplementing with missing vitamins can restore good health

Major Roles of Vitamins

• Vitamins have hormonal action (e.g., vitamin D)
• Vitamins participate in chemical reactions (e.g., anti-oxidation)
• Vitamins do not provide energy
• Vitamins regulate various bodily processes (e.g., cell division, tissue growth)

Radical Formation and Vitamins

• Oxidation reactions form radicals ("free radicals")
• Radicals are substances with an unpaired electron and involve the loss of electrons
• Free radicals are highly reactive and unstable
• Free radicals can remove electrons from more stable molecules (e.g., DNA, proteins, polyunsaturated fatty acids)
• Free radical damage contributes to chronic diseases and premature aging
• Vitamins (e.g., vitamin E, vitamin C) have anti-oxidation effects

How Do Antioxidants Work?

• Antioxidants donate an electron to stabilize a radical
• By donating an electron, the radical is stabilized, protecting other molecules

Free Radicals and Antioxidants

• Free radicals have an unpaired electron; antioxidants donate an electron to stabilize them.

Sources of Vitamins

• Vitamins occur naturally in food, or are synthesized in labs (supplements)
• Biological activity refers to the effect of vitamins in the body
• Some vitamins are more active in natural form, while others are more active in synthetic form (e.g., folate)
• Bacteria in the large intestine produce certain vitamins (biotin and vitamin K), and the body can synthesize vitamin D and niacin under certain conditions.

How are Vitamins Classified?

• Fat-soluble vitamins (A, D, E, and K) are associated with lipids in food and the body
• Fat-soluble vitamins do not dissolve in water or urine, generally are stored in the body, and can be toxic in excessive amounts
• Water-soluble vitamins (C and B-complex, including B1, B2, B3, B6, B7, B9, B12, and Choline) dissolve in watery components of food and the body.
• Water-soluble vitamins are usually not stored in significant amounts and are generally non-toxic

Vitamin Enrichment and Fortification

• Raw foods can lose nutrients during processing (like refinement)
• Grain enrichment adds thiamin, riboflavin, niacin, folic acid, and mineral iron to refined grains to restore nutrients lost during processing
• Fortification adds any nutrient to a wide array of commonly eaten processed foods during manufacturing

Vitamin Absorption

• Most vitamins are absorbed in the small intestine.
• Absorption increases when the body requires more of the vitamin
• Fat-soluble vitamins are absorbed along with dietary fat.
• Diseases affecting the GI tract can reduce vitamin absorption (e.g., cystic fibrosis)

Vitamin Deficiency and Toxicity Disorders

• Deficiencies can result from poor diets or certain health conditions.
• In the U.S., severe deficiencies are uncommon due to food preservation, enrichment, and fortification, plus widespread fruit and vegetable availability
• Some Americans don't consume sufficient amounts of vitamin E, D, and choline

Populations at Risk for Vitamin Deficiency

• Alcoholics
• Older adults
• Hospitalized people
• People with anorexia nervosa
• People with certain gastrointestinal disorders
• People with rare metabolic conditions

Maximizing Vitamin Contents of Food

• Vitamin C, thiamine, and folate are easily destroyed by poor storage and preparation practices
• Niacin and vitamin D tend to be very stable
• Tips for preserving vitamin content: avoid wilted, bruised, or shriveled produce; cook in small amounts of water; avoid large pieces of food; use quick cooking methods (e.g., microwaving, steaming, stir-frying); freeze produce

Vitamin A

• Animal sources: retinol (most active form) – liver, fish liver oils
• Plant sources: beta-carotene (provitamin A) – yellow-orange and green fruits and vegetables
• Major functions: normal vision, reproduction, cellular growth, immune system activity, and epithelial cell production
• See page 20 on the presentation for a table of vitamin A in various foods

Vitamin D

• Major functions: increasing calcium and phosphate deposits in bone, reducing urinary calcium excretion, and increasing calcium and phosphate absorption
• Synthesis occurs in skin when exposed to ultraviolet light
• See presentation pages 25-29 for major sources

Vitamin E

• Major functions: antioxidant activity, maintenance of the nervous and immune system
• See pages 33-35 for major sources

Vitamin K

• Major Functions: produces active blood-clotting factors
• See pages 36-38 for major sources

Water-Soluble Vitamins

• Many function as components of specific coenzymes (small molecules that help enzymes function)
• Enzymes require coenzymes to function. Coenzymes regulate chemical reactions by interacting with enzymes. Once activated, the coenzyme-enzyme complex enables the reaction to occur
• See pages 39-40 for major sources

Thiamin (B1)

• Part of coenzyme involved in energy release from carbohydrates.
• Involves metabolism of certain amino acids.
• Synthesis of neurotransmitters
• Deficiency Disease: Beriberi; Wernicke-Korsakoff syndrome (alcoholics)
• See Page 41 for food sources

Riboflavin (B2)

• Coenzyme for metabolism of carbohydrates, lipids, and amino acids.
• Dairy foods, liver, enriched grains are significant food sources
• See Page 43 for food sources

Niacin (B3)

• Part of two coenzymes necessary to obtain energy from macronutrients
• Deficiency can result in dermatitis, diarrhea, dementia, and death ("4 D's" of pellagra)
• High doses (megadoses) can cause GI ulcers, vision problems, and liver damage
• See Page 44 for food sources

Vitamin B6

• Part of coenzyme needed for amino acid metabolism
• Deficiency rarely occurs but can lead to dermatitis, anemia, convulsions, depression, and confusion
• High doses (megadoses) can cause nerve damage
• See Page 46 for food sources

Folate

• Part of the coenzyme tetrahydrofolic acid (THFA) required for DNA and amino acid metabolism.
• Converts homocysteine into methionine, and plays a major role in vitamin B12 function
• Leafy greens, liver, legumes, asparagus, and oranges are significant food sources
• See pages 47-49 for details

Vitamin B12

• Part of coenzymes needed for folate metabolism and myelin sheath maintenance.
• Binds to intrinsic factor for absorption in the ileum
• Food-cobalamin (B12) malabsorption is common in older adults due to declining gastric acid production.
• See pages 56-57 for details

Pantothenic Acid and Biotin

• Pantothenic acid (B5) is a component of coenzyme A, critical for energy metabolism and fatty acid production. Pantothenic acid is widely available in foods
• Biotin (B7) participates in chemical reactions adding carbon dioxide to other compounds, promoting the synthesis of glucose and fatty acids and breaking down amino acids.
• Intestinal bacteria produce biotin, preventing biotin deficiencies

Vitamin C

• Not part of a coenzyme, but needed for collagen synthesis, antioxidant activity, immune system function, and the synthesis of bile and some neurotransmitters and hormones
• Deficiency results in scurvy
• See pages 55-57 for details

Choline

• Humans need choline, especially during prenatal development
• Choline is a vitamin-like nutrient
• The body can produce choline but may not produce enough in certain conditions
• See page 58 for details

Vitamin as Medicine

• Niacin (B3): can lower LDL cholesterol and raise HDL cholesterol, but high doses are toxic.
• Vitamin B6: some research suggests it may help with PMS, but high doses can cause nerve damage
• Folic Acid, B6, B12: lower blood homocysteine levels when taken together; research on CVD reduction and Alzheimer's disease prevention is mixed/inconclusive
• Vitamin C: does no prevent colds, but may reduce duration and severity; has antioxidant activity
• Vitamin E: questionable benefits for reducing chronic disease/cancer risks and may increase cancer risk
• Carotenoids (as supplements): may help reduce AMD progression but possibly harmful, especially for smokers

Cancer

• Group of chronic diseases; characterized by cells with mutated (damaged) genes
• Cancerous (malignant) cells are out of control; can spread (metastasize)
• Carcinogens are environmental factors that trigger cancer; examples can be age, tobacco use, radiation exposure, certain bacteria/viral infections, certain hormone levels, alcohol, certain specific foods, and other environmental exposure)
• See pages 65-67 for details

Reducing Cancer Risk

• Limit alcohol
• Maintain a healthy weight
• Adopt physically active lifestyle
• Eat a healthy diet, emphasizing plant foods, and limiting red and processed meats
• Avoid environmental exposures to carcinogens

Test your knowledge on essential vitamins, their functions, and the risks of deficiencies. This quiz covers the importance of vitamins A and D, the consequences of their lack, and ways to maintain vitamin content in foods. Challenge yourself to see how well you understand these crucial nutrients.