Vitamins and Nutrition Overview Quiz

Vitamins

• Vitamins are organic molecules needed in small amounts for proper organism function.
• Vitamin needs vary by organism.
• Fat-soluble vitamins include A, D, E, and K.
• Water-soluble vitamins include the B complex (9) and C.
• Provitamins are precursors to vitamins.
• Vitamers are different forms of a vitamin.
• Vitamins are often measured in IU (International Units).
• Chemical structures are shown for properties, not rote memorization.

Vitamins and Steroids - Cautions

• Popular science books on vitamins often misrepresent the value of individual vitamins for treating conditions.
• Proper understanding necessitates use of textbooks and peer-reviewed journal articles.
• Chemical structures are shown for understanding properties, not rote memorization.

Vitamins and Steroids - Outline

• Hypovitaminoses (vitamin deficiencies) are considered only for well-known conditions.
• General terminology and groupings of vitamins A, D, E, and K are covered.
• Detailed properties, sources, role in vivo, and provitamins/vitamers for these vitamins are included in the outline.

Definition and Groupings

• Vitamins are organic molecules needed in small amounts for proper organism function.
• Fats-soluble vitamins include A, D, E, and K - these are not created by the body and so must be consumed via diet.
• Water-soluble vitamins include the B complex (9) and C - these are sometimes created by the body.
• Provitamins are precursors to vitamins.

Fat-Soluble: Vitamin A

• All vitamers are isoprenoids.
• Important vitamers include: retinol, retinal, retinoic acid, retinyl esters.
• Key for plant-derived and some animal-derived foods.
• Retinal is needed for low-light vision and also found in some Archaea.
• Retinoids are needed for sperm development and other processes.
• Retinoic acid can reverse photoaging and is used to treat acne/cancer.
• β-carotene, α-carotene, and γ-carotene are provitamins found in plants, used to create retinol in the body.
• Retinyl palmitate is a common dietary form and storage form.
• Consumption of Vitamin A above a prescribed level can be toxic.

Hypovitaminosis A

• Xerophthalmia: thickening/hardening of the surfaces of the eyes.
• Keratomalacia: inability of the eye to synthesize surface tissues, leading to an opaque cornea.
• Nyctalopia: inability to see in low light, due to lack of retinaldehyde and thus rhodopsin in the retina.
• Photophobia: aversion to bright light due to rhodopsin properties in retina.

Carotenoids in the Aves

• Birds acquire carotenoids from their food source, which comes from all three domains (Bacteria, Archaea, and Eukarya).
• Some notable pigments include Beta-carotene and astaxanthin.
• Examples of carotenoids include bacterioruberin, echinenone, and astaxanthin which have red pigmentation.

Fat-Soluble: Vitamin D

• Vitamins D are secosteroids (broken steroids) with notable vitamers: ergocalciferol (D2), cholecalciferol (D3), 22-dihydroergocalciferol (D4), sitocalciferol(D5).
• They regulate calcium uptake in intestinal systems.
• Insufficient vitamin D leads to rickets (bone softening), osteomalacia in adults, and osteoporosis.

Hypovitaminosis D

• Rickets (children): Bone softening.
• Osteomalacia (adults): Bone softening.
• Osteoporosis: Bones become porous and fragile.
• Clinical depression and clinical anxiety commonly found in hypovitaminosis D, along with other symptoms like muscular pain and muscle twitching.

Fat-Soluble: Vitamin E

• Eight vitamers, four tocopherols and four tocotrienols.
• α-tocopheryl acetate is often used in supplements.
• A potent antioxidant.
• Protects cell membranes from oxidative stress by donating electrons to oxidizing agents such as reactive oxygen species (ROS).
• Deficiency is rare and causes neurological damage.

Fat-Soluble: Vitamin K

• Two vitamers: phylloquinone (K₁) and menaquinones (MKs).
• Essential for blood clotting and calcium metabolism.
• Obtained from gut microflora, such as Escherichia coli, which then release K₁ into the digestive system.
• Also found in green leaves and leafy vegetables.
• Deficiency in Vitamin K leads to blood clotting issues.

Water-Soluble: Vitamin C

• Two vitamers: L-ascorbic acid (L-ascorbate) and dehydroascorbic acid (dehydroascorbate).
• An antioxidant protecting cell membranes from damage.
• A cofactor for hydroxylases involved in collagen synthesis.
• May help prevent scurvy.
• Rosehips, blackcurrants, kale, and citrus fruits are good vegetable sources of ascorbic acid.

Hypovitaminosis C

• Scurvy is the overarching condition with other symptoms such as bleeding gums, generalized muscle pains, fatigue, anemia from low erythrocyte production, easy bruising, wounds not healing, neuropathy, jaundice, dry eyes, dry mouth, dental caries, mouth ulcers, personality changes, and edema.

Water-Soluble: Thiamine (B₁)

• A cofactor for various enzymes, particularly those in the pyruvate dehydrogenase complex.
• Essential for many microorganisms.
• Beri-beri is characterized by various neuro symptoms.

Water-Soluble: Riboflavin (B₂)

• Enzyme cofactors (flavins, e.g. FMN and FAD).
• Essential for many microorganisms.
• Ariboflavinosis is hypovitaminosis B₂.
• Obtained from milk, eggs, meat, green vegetables, and legumes.

Water-Soluble: Niacin (B₃)

• Enzyme cofactors (NAD+ and NADP+).
• Essential for many microorganisms.
• Pellagra is characterized by neuro symptoms, skin rashes, and deficiency.
• Obtained from meat, red fishes, grains.

Water-Soluble: Pantothenic Acid (B₅)

• Provitamin: panthenol.
• Enzyme cofactor coenzyme A (CoA).
• Essential for many microorganisms.
• Deficiency is very rare.
• Obtained from milk, eggs, potatoes, tomatoes, and oats.

Water-Soluble: Pyridoxal 5'-Phosphate (B₆)

• Enzyme cofactor itself in many enzymes.
• Vitamers include pyridoxine (PN), pyridoxal (PL), PL 5-phosphate, PN 5-phosphate, and pyridoxamine (PM).
• Essential for many microorganisms.
• Deficiency leads to skin and neurological issues.
• Obtained from meat, red fishes, grains.

Water-Soluble: Biotin (B₇)

• Enzyme cofactor in many carboxylases.
• Essential for many microorganisms.
• Regulates gene expression (in some ways).
• Deficiency leads to rashes and hallucinations (in various ways).
• Obtained from meat, eggs, yeast, and legumes.

Water-Soluble: Folic Acid/Folate (B₉)

• Involved in DNA biosynthesis.
• Essential for many microorganisms.
• Deficiency causes anaemia and impaired neural tube development in pregnancy.
• Sources include seeds, legumes, grains, green leafy vegetables.

Water-Soluble: p-Aminobenzoic Acid (B₁₀)

• Key for folate synthesis in various microorganisms.
• Essential for many microorganisms.
• Deficiency is very rare.

Water-Soluble: Cobalamins (B₁₂)

• Involved in amino acid and fatty acid biosynthesis. cofactor in methyltransferases/isomerases.
• Vitamers include hydroxycobalamin, adenosylcobalamin (adoB₁₂), and methylcobalamin (MeB₁₂).
• Essential for many microorganisms.
• Deficiency causes anemia, fatigue, joint pain, reduced heart function, depression and psychosis.
• Obtained from meat and fish (and other animal sources) where synthesized by microorganisms.

Test your knowledge on fat-soluble and water-soluble vitamins, provitamins, and the effects of hypovitaminosis. This quiz covers key concepts related to vitamins, their classifications, and daily intake recommendations. Perfect for students and enthusiasts of nutrition science.