Vitamins and Their Functions Quiz

Objectives

• Students will understand the basics of vitamins, including bioavailability and the difference between fat-soluble and water-soluble vitamins.
• Students will list fat-soluble and water-soluble vitamins.
• Students will list the properties of vitamins, including their roles in the body, deficiency diseases, toxicity, symptoms, and reasons for their occurrence.
• Students will learn about interactions between vitamins and medications.
• Students will know the types of people who may benefit from a supplement, and which ones, and why.
• Students will discuss the reasons for taking supplements, and the risks and benefits of using supplements.

Definitions & Classification of Vitamins

• Vitamins are organic compounds, essential for life that do not provide energy
• Micronutrients
• Indispensable to body functions

Precursors = Provitamins

• Transform chemically into one or more active forms. Examples include beta-carotene.

Bioavailability

• The rate and extent to which a nutrient is absorbed and used.

Definitions

• Malnutrition: an imbalance of nutrient intake or an excess/deficiency
• Undernutrition: deficient in energy or nutrients
• Overnutrition: excess energy or nutrients
• Primary deficiency: inability of the body to absorb enough nutrients due to an insufficient intake
• Secondary deficiency: deficiency relating to an underlying issue. This can occur due to a disease condition, a drug's interaction, or the destruction of the nutrient
• Subclinical deficiency: a deficiency that doesn't show outward signs.

Fat-soluble Vitamins: A, D, E, K

• General characteristics of fat soluble vitamins:
  • Absorbed into the lymph system
  • Require bile for absorption
  • Travel through the blood with protein carriers
  • Stored in the liver and fatty tissues
  • Can be toxic in excess

The Fat-Soluble Vitamins

• Found in fats and oils of foods
• Require bile for absorption
• Stored in the liver and fatty tissues
• The body can survive for weeks without consuming these vitamins.
• Vitamin A & D supplements can reach toxic levels and easily.

Deficiency

• Likely if consistently low in fat-soluble vitamins
• Fat malabsorption
• Mineral oil laxatives can cause vitamin loss
• Extraordinarily low-fat diets interfere with absorption

Vitamin A

• 3 forms active in the body: retinol, retinal, retinoic acid
• Plant-derived precursor: beta-carotene
• Roles: Vision, gene expression, maintenance of body linings and skin, immunity, growth of bones and of the body, normal development of cells, important for reproduction.
• Eyesight: Light passes through the cornea before it reaches the retina. The retina contains light-sensitive nerve cells. Light bleaches the vitamin A-containing pigment rhodopsin, resulting in an impulse to the optic center of the brain. Vitamin A must regenerate after a flash of bright light for clear vision in dimly lit conditions. If vitamin A levels are too low, night blindness can occur.
• Keratinization of the cornea. Dryness and thickening of the cornea during vitamin A deficiency can lead to permanent blindness.
• Skin and body linings: Vitamin A is necessary for all epithelial tissues, acting as a protective barrier from pathogens and other damages.
• Control of gene expression.
• Immunity.
• Growth.
• Deficiency: Cell differentiation and maturation are impaired. Failure of mucus-producing cells to produce mucus causes a subsequent increase in keratin-producing cells. Tissues become vulnerable to infections such as respiratory infection.
• World-Wide Deficiency: Severe vitamin A deficiency affects almost 10 million children worldwide, leading to conditions such as xerophthalmia (eyesight issues), blindness, and other health problems
• Vitamin A Toxicity: Can cause weakening of bones, bone and joint pain, abdominal pain, stunted growth and liver damage in large doses

Vitamin D

• Not essential in some areas
• The body can produce vitamin D with help from sunlight
• Many people may border on vitamin D insufficiency.
• Regulates blood calcium and phosphorus levels
• Maintains bone integrity
• Promotes calcium absorption and retention
• Functions as a hormone that draws calcium from bone
• Plays a vital role in the brain, heart, stomach, pancreas, skin, reproductive organs, some immune system cells and stimulates cell maturation including immune system cells
• Deficiency can lead to issues like high blood pressure, some cancers, type 1 diabetes, heart disease, inflammatory bowel disease, and multiple sclerosis
• Deficiency in Children: Rickets, characterized by abnormal bone growth (bowed legs, outward-bowed chest, knobs on ribs)
• Health Canada: Recommendations for breastfed babies to receive a 400 IU vitamin D supplement daily to prevent rickets.
• Risk of bone loss: Adolescents who consume beverages without vitamin D, prefer indoor activities, and many older adults at risk of vitamin D deficiency
• Osteomalacia: The adult form of rickets most often affects women with low calcium intake, little sun exposure, and going through pregnancies and lactation
• Too much vitamin D: Toxicity includes loss of appetite, nausea, vomiting, increased urination, thirst, and severe psychological depression
• The body can make vitamin D from sunlight exposure; the precursor compound is absorbed into the blood stream, liver and kidneys convert to the active form of vitamin D
• Risk of toxicity is low from skin synthesis, but factors like skin color, outdoor time, supplements, sunscreen, city living, clothing and geographical regions contribute to it

Vitamin E

• Consists of 4 tocopherol compounds
• Alpha-tocopherol is main compound
• Antioxidant activity
• Protects cells from oxidative damage
• Oxidative damage results from free radical
• Free radical activity may contribute to cancer and other diseases
• Antioxidant effects are crucial for lungs, protecting red and white blood cells, and possibly immunity and nerve development
• Deficiency: Infants born before the transfer of vitamin E from mother to infant. Erythrocyte hemolysis, causing anemia. Nerve damage and associated conditions. Low intake with extremely low-fat diets over years. Reliance on fat replacers instead of fat
• Toxicity: No observed toxicity with natural food sources. Large doses can increase the effects of blood thinners. May be a risk of death from supplements over 400IU.
• Food sources: Vegetable oils, including salad dressings. Avocados, wheat germ. Smaller amounts in meat, poultry, fish, eggs, milk products, nuts and seeds (low in animal fats).

Vitamin K

• Functions: Synthesis of blood clotting proteins. Interfere with medications such as blood thinners
• Consistent intake of vitamin K rich foods
• Avoid drastic changes in self-prescription vitamin K supplements
• Synthesis of normal bone form proteins that bind minerals to bone
• Sources: Intestinal bacteria (can’t meet body needs), leafy green vegetables (spinach, collard greens, beet greens, Swiss chard), cabbage and other members of cabbage family, canola & soybean oils, eggs & milk (small amounts), liver (rich animal source)
• Newborns receive a dose to establish vitamin K-producing bacteria
• Deficiency: Unlikely in adults. Risks in newborns, antibiotic treatment, and fat malabsorption
• Toxicity: No upper limit. Rarely occurs in healthy adults. Can occur in infants and pregnant women who over-supplement with synthetic vitamin K
• Deficiency leads to jaundice, bilirubin in brain, and potential brain damage or death

Water Soluble Vitamins: C & B Vitamins

• General advice for meeting needs: Choose foods daily that are rich in water soluble vitamins to meet daily recommendations

Vitamin C

• 200 years ago, crews on ships had a 50% chance of dying

• Short trips near Mediterranean: no scurvy

• High death rate on long voyages

• Fruits and vegetables used up early on long trips

• James Lind first experimented to find a cure

• Early experiments: Sailors divided in groups. Groups received different supplemental rations such as cider, vinegar, sulfuric acid, seawater, oranges and lemons. Citrus groups recovered quickly

• Scurvy: Vitamin C (ascorbic acid) deficiency

• Treatments included lime juice

• Roles of vitamin C: Maintenance of connective tissues, collagen production, bones, teeth, skin. Tendons, scar tissue, and capillaries. Antioxidants

• Antioxidant activity protects substances like iron from oxidation, promoting absorption, and protecting vitamin E

• Deficiency symptoms: Collagen breakdown causing symptoms like loose teeth, bleeding gums, pinpoint hemorrhages (blood vessels rupture beneath skin), anemia, loss of appetite and stopped growth

• Risk of Scurvy: Low in North America though exceptions include the elderly, impoverished, and those with drug/alcohol addictions

• Curing Scurvy: With 100 milligrams of vitamin C per day for 5 days

• Vitamin C and Cold: Supports immune system function

• Benefits with high doses early in colds:

• Shortens cold duration by day and half. Reduced symptoms by 40%

• 2 grams per day for 2 weeks reduces blood histamine. Substance responsible for runny/stuffy nose

• Placebos: can help or hinder; Some receive a placebo thinking it's Vitamin C; Others receive Vitamin C thinking it's a placebo.

• Toxicity: Vitamin C from food is safe, adverse effects include digestive upsets, nausea, abdominal cramps, excessive gas and diarrhea

• Large doses: May interfere with medications that prevent blood clotting and can also cause danger for those that have an overload of iron

• Smoking depletes Vitamin C; RDA for smokers is higher (35mg higher)

Food Sources of Vitamin C

• Citrus fruits; Dark green vegetables; Cabbage type vegetables; Strawberries; Cantaloupe; Lettuce; Tomatoes; Papaya; Mangos; Red bell pepper
• Potatoes contain Vit. C - became apparent in Ireland during potato famine
• Fresh, cooked are best; prone to degradation by heat and oxygen
• Proper storage and consumption needed for food

The B Vitamins

• B vitamins act as parts of coenzymes. Coenzymes combine with and activate an enzyme that is part of the metabolism process for carbohydrates, proteins, and lipids
• Examples of B Vitamins include: Thiamin, Riboflavin, Niacin, Pantothenic acid, Biotin, Vitamin B6, Folate, vitamin B12
• Thiamin, riboflavin, niacin, pantothenic acid and biotin help nutrients release energy
• Vitamin B6 helps the body make protein
• Folate and vitamin B12 help cells multiply
• Deficiency in B vitamins typically involves symptoms like digestive tract and blood damage as well as possible permanent consequences
• B vitamin deficiencies rarely occur in isolation.

Thiamin (Vitamin B1)

• Role: Energy metabolism, nerve processes (muscles)
• Deficiency: Beriberi -loss of sensation in the hands & feet, abnormal heart action (muscular weakness; advancing paralysis), edema (wet beriberi), and no edema (dry beriberi).
• First observed with polishing of rice in Asia
• Deficiency: Wernicke-Korsakoff syndrome- Alcohol abuse is associated with severe thiamin deficiency due to displacement of food groups that contain thiamin.
• Sources: Widely spread among healthy foods; pork, sunflower seeds, whole grain cereals, legumes

Riboflavin (Vitamin B2)

• Role: Energy metabolism of all cells
• Deficiency: Ariboflavinosis commonly occurring with other severe vitamin deficiencies. Commonly associated with inflammation of the membranes of the mouth, skin, eyes and GI tract and a smooth/purplish red tongue; not noticeable at first because thiamin deficiency is more severe
• Sources: In healthy foods such as milk products, milk, leafy green vegetables, whole grain breads, enriched/fortified grain products and some meats and eggs

Niacin (Vitamin B3)

• Role: Energy metabolism
• Deficiency: Pellagra ("4 Ds") - Diarrhea, dermatitis, dementia and death
• At risk: Poorly nourished/impoverished people, particularly alcohol abusers
• Sources: Tryptophan (abundant in proteins), converted to niacin and can be obtained from milk, eggs, nuts and seeds (also via synthesis from tryptophan)

Folate

• Role: DNA synthesis, part of coenzymes for cell synthesis
• Deficiency: Immature red and white blood cells and GI tract cells affected resulting in megaloblastic/macrocytic anemia (large, immature red blood cells) Decreased immune system, abnormal digestive function, increased risk of cardiovascular disease, colon, or cervical cancer.
• Neural Tube Defects: Most commonly during pregnancy, characterized by problems with spinal cord, mental delay, or death, especially within a few days to weeks of birth. Fortification with folic acid has minimized occurrence since 1990s
• Toxicity: Can mask vitamin B12 deficiency; Excess intake may interfere with anticancer drugs
• Units of measurement: Dietary Folate Equivalent (DFE) converts all forms of folate to a standardized unit in food
• Bioavailability: Ranges from approx 50% to 100%
• Food sources: Leafy green vegetables, fresh uncooked vegetables and fruits, eggs, orange juice, legumes.
• Recommendations per dosage: Health adults: 400 mcg DFE/day. Pregnancy: 600 mcg DFE/day

Vitamin B12

• Close relationship with folate; Activated by folate, and activated vitamin B12 activates folate
• Role: Maintenance of nerve fibers
• Deficiency: Damaged nerve sheaths, creeping paralysis; General nerve/muscular impairment
• Deficiency results in folate failure to make red blood cells
• Deficiencies of folate, B12, or B6 cause excess homocysteine buildup that can indicate issues and potential risk with cardiovascular disease
• Deficiency risk in elderly due to absorption problems, decreased intrinsic factor from decreased stomach acidity, and atrophic gastritis
• Deficiency risk in vegans due to limited animal sources of vitamin
• Pernicious anemia: A vitamin B12 deficiency/disease caused by a lack of intrinsic factor and characterized by large, immature red blood cells
• Treatment: B12 injections
• Sources: Animal sources (milk, fish); fortified plant foods (soy beverage)

Vitamin B6

• Role: 100+ reactions in tissues,needed amino acids, protein synthesis, converts tryptophan to niacin, neurotransmitter and hormone synthesis
• Deficiency: General symptoms; Weakness; Psychological depression; Confusion; Irritability; Insomnia; Anemia; Greasy skin dermatitis; Convulsion symptoms; May weaken immune system
• Toxicity: Seen in women taking 2+ g/day for 2+ months; Numb feet, reduced sensation in hands; Unable to walk/work, eventually recover after stopping supplements
• Need is proportional to protein intake
• Stored mostly in muscle tissues
• Sources: Protein-rich foods (meats, fish, poultry, legumes, peanut butter); potatoes; leafy green vegetables; some fruits

Biotin

• Role: Part of energy metabolism, coenzyme for carbohydrate, fat, and protein
• Deficiency: Consumption of raw eggs, binders that prevent absorption
• Sources: Widespread in foods

Pantothenic Acid

• Role: Part of energy metabolism; release of energy from carbohydrates, fats, and proteins
• Deficiency: May occur in rare diseases
• Sources: Widespread in the foods

Controversy: Vitamin Supplements

• Overall, supplements benefit are questionable for healthy adults
• The majority of Canadians consume them. Experts usually recommend supplements only if a deficiency risk exists.
• Likely deficiencies exist in populations such as people who have poor diets; those on medications (that interferes with nutrient absorption); Vegans, those who have disorders that impair their absorption; those in stages of life with particular nutritional needs (infants who need iron, pregnant individuals who need folate, elderly individuals); elderly or have conditions that impair absorption