Vitamins and Their Functions Quiz

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Questions and Answers

What best describes the term 'bioavailability' in relation to vitamins?

The energy yield from organic compounds in food

The measure of vitamin content in food including its activity potential

The chemical transformation of vitamins into active forms

The rate and extent of nutrient absorption and usage in the body (correct)

Which component is NOT a characteristic of vitamins?

They are organic compounds

They are classified as micronutrients

They are essential for body functions

They yield energy for the body (correct)

Which of the following options correctly defines 'provitamins'?

The active forms of vitamins that provide energy

Vitamins that are synthesized by the body

Vitamins that do not require dietary sources for function

Inactive forms that convert into active vitamin forms (correct)

Which statement regarding fat soluble and water soluble vitamins is accurate?

Fat soluble vitamins can be stored in the body while water soluble cannot Signup and view all the answers

Which group is most likely to require vitamin supplementation?

Pregnant women who have specific dietary restrictions Signup and view all the answers

What effect does a deficiency of vitamin A have on night vision?

It causes a delay in regaining vision after exposure to bright light. Signup and view all the answers

What is the initial consequence of vitamin A deficiency on the cornea?

Keratin accumulation leading to thickening. Signup and view all the answers

What role does vitamin A play in cell differentiation?

It allows cells to develop and perform specific functions. Signup and view all the answers

What condition can develop from severe vitamin A deficiency in the eyes?

Xerophthalmia. Signup and view all the answers

What happens to rhodopsin when it is bleached by light?

It releases vitamin A and initiates a visual impulse. Signup and view all the answers

What can reverse the keratinization in the cornea caused by vitamin A deficiency?

Vitamin A supplementation and dietary improvements. Signup and view all the answers

Why is vitamin A crucial for epithelial tissues?

It helps in the protection against pathogens and damage. Signup and view all the answers

What is the primary benefit of beta-carotene in the diet?

Reduces the risk of macular degeneration Signup and view all the answers

Which food source is considered rich in beta-carotene?

Spinach Signup and view all the answers

What is the relationship between beta-carotene supplements and cancer risk in smokers?

They are associated with an increased risk of cancer. Signup and view all the answers

Which vitamin is considered one of the major dietary antioxidants along with beta-carotene?

Vitamin C Signup and view all the answers

Vitamin A is predominantly found in which type of food?

Animal-origin foods Signup and view all the answers

What effect does having an adequate intake of vitamin A have on the influence of beta-carotene?

It has no impact on the effectiveness of beta-carotene. Signup and view all the answers

Which of the following is a risk associated with a lack of foods rich in beta-carotene?

Higher likelihood of macular degeneration Signup and view all the answers

Which food item is considered a good source of vitamin A?

Fish oil Signup and view all the answers

What characteristic is shared by beta-carotene and other dietary antioxidants?

They help protect cells from oxidative stress. Signup and view all the answers

What was observed regarding high doses of vitamin C taken at the onset of a cold?

It reduces the severity of symptoms by approximately 40%. Signup and view all the answers

What effect does 2 grams of vitamin C per day for two weeks have on blood histamine levels?

It reduces blood histamine levels. Signup and view all the answers

What potential side effects can arise from excessive vitamin C intake?

Digestive upset, including nausea and diarrhea. Signup and view all the answers

How does a placebo effect relate to vitamin C consumption according to the studies?

Placebo subjects reported fewer colds despite not receiving vitamin C. Signup and view all the answers

Which of the following groups could potentially be harmed by high doses of vitamin C?

Those with an overload of iron. Signup and view all the answers

What role does vitamin C play in relation to histamine?

It may function like a weak antihistamine. Signup and view all the answers

What is the general consensus about vitamin C and colds?

It shows inconsistent results in preventing or relieving colds. Signup and view all the answers

Which of the following statements about vitamin C is incorrect?

Vitamin C should be consumed in massive doses daily. Signup and view all the answers

In what way might vitamin C enhance the immune system?

Through its antioxidant properties or other activities. Signup and view all the answers

Study Notes

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

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Description

Test your knowledge on vitamins, their functions, and deficiencies with this quiz. Explore the importance of vitamin A, the concept of bioavailability, and the role of provitamins in nutrition. Designed for students learning about dietary vitamins and their impact on health.