Vitamins: Biochemical Roles Quiz

Vitamins: Biochemical Roles

• "Vitamin" means "vital for life"
• Vitamins are micronutrients (needed in small amounts - mg or µg) necessary for daily bodily functions
• Vitamins cannot be synthesized in the body; thus, they must be obtained through diet
• Vitamins are necessary for healthy diets and play vital roles in cellular metabolism
• Though present in small amounts within cells, they are crucial
• Their absence frequently manifests as deficiency diseases

What are Vitamins?

• Vitamins are non-caloric organic nutrients
• They aid in bodily processes like digestion, absorption, metabolism, and growth
• Some vitamins appear in food as precursors (or provitamins)

Vitamins and Coenzymes

• Vitamins often function as coenzymes
• Coenzymes are small molecules that work with enzymes to promote enzyme activity
• Coenzymes can be bound very tightly (or covalently) to enzymes, forming a prosthetic group
• A holoenzyme is a complete, catalytically active enzyme joined with its coenzyme
• The protein portion of a holoenzyme is called the apoenzyme or apoprotein

Vitamin Intake and Measurement

• Humans need at least 12 vitamins in their diet
• A well-balanced diet from a variety of food sources usually provides sufficient vitamins
• Some vitamins are chemically altered in the body for proper function
• Some vitamins are measured in International Units (I.U.s), a measure of biological activity (biological activity)
• This system is often necessary because many vitamins have multiple forms with equal weights, but different activities
• Other vitamins are measured by weight (mg or µg)

Vitamins - US FDA Recommendations

• The Food and Drug Administration (FDA) sets Daily Reference Intakes (DRIs)
• DRIs encompass the highest vitamin amounts needed by 95% of the population
• DRIs include Estimated Average Requirements (EAR), Recommended Dietary Allowances (RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL), replacing the 1989 RDAs

Vitamins - Categories

• Vitamins are categorized into two groups:
  • Water-soluble vitamins
    • The "B" vitamins (Pantothenic acid, Biotin, Folic acid, etc.)
    • Vitamin C
  • Fat-soluble vitamins
    • Vitamins A, D, E, K

Water-soluble vs. Fat-soluble Vitamins

• Water-soluble vitamins:
  • Cannot be stored in the body
  • Excess is excreted in urine
  • Unstable to heat and light, leaching into cooking liquids
• Fat-soluble vitamins:
  • Can be stored in the body
  • Can accumulate to toxic levels if large amounts are ingested
  • Relatively stable at normal cooking temperatures

Water-soluble Vitamins (details)

• Found in vegetables, fruits, grains, and meats
• Absorbed directly into the bloodstream
• Not stored in the body, reducing toxicity risk
• Alcohol, smoking, etc., can decrease absorption
• Dissolve in water; subject to cooking losses
• Generally readily excreted by the body
• Absorbed at between 50% and 90%
• Often function as coenzymes in energy metabolism

B-Vitamins

• B vitamins are coenzymes essential for cellular function
• Key B vitamins include thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folic acid (B9), and cyanocobalamin (B12)

Vitamin B1 (Thiamin)

• Important in energy production from carbohydrates, nerve function, and appetite
• Sources include fish, liver, legumes, whole grains, and enriched grains
• Deficiency can cause beriberi
• Nontoxic at high dosages

Vitamin B2 (Riboflavin)

• Involved in energy production, carbohydrate metabolism, tissue/organ health, immunity, and red blood cell function
• Sources include milk, eggs, meats, leafy green vegetables and enriched grains
• Deficiency can cause cracks and sores around mouth, and skin conditions
• Nontoxic at recommended levels

Vitamin B3 (Niacin) and Niacinamide

• Essential for energy production, skin/tongue health, nerve function, digestive function, and cholesterol regulation
• Sources include milk, eggs, meats, leafy greens, and enriched grains
• Deficiency can cause Pellagra, characterized by dermatitis, diarrhea, dementia, and potential death
• High dosages may sometimes result in skin flushing

Vitamin B6 (Pyridoxine)

• Crucial for amino acid and fatty acid metabolism, and red blood cell creation
• Sources include meats, fish, poultry, legumes, fruits, potatoes, whole grains, soy products
• Deficiency linked to anemia (small-cell type) and various nervous system issues
• High dosages can cause bloating, fatigue, impaired memory, and other issues

Vitamin B9 (Folate)

• Important for cell synthesis
• Sources include asparagus, avocados, leafy greens, beets, legumes, seeds, liver, enriched breads, cereals, pasta, and grains
• Deficiency can cause anemia (large-cell type) and issues with pregnancy development
• High dosages potentially mask vitamin B12 deficiency

Vitamin B12 (Cobalamin)

• Crucial for new cell creation and nerve maintenance
• Sources include animal products
• Deficiency can lead to anemia (large-cell type) and nerve issues(i.e. fatigue, nerve degeneration, and paralysis)
• High doses have no known toxicity issue

Vitamin B5 (Pantothenic Acid)

• Component of a key coenzyme in metabolic processes such as energy production
• Found widely in most foods
• Deficiency symptoms are usually associated with digestive and neurological processes
• High dosages may lead to water retention

Vitamin B7 (Biotin)

• A cofactor in several enzymatic reactions connected to energy metabolism, fat synthesis, amino acid metabolism and glycogen synthesis
• The vitamin is present in widespread amounts in various foods
• Deficiency can lead to fatigue, insomnia, intestinal dysfunctions, and other nervous system issues
• High dosages typically have no known toxicity issues

Vitamin C

• An antioxidant that protects cells from damage; aids in collagen production (critical for wound healing and blood vessel walls); critical for iron absorption; vital for immune system, and protects against various diseases
• Sources include leafy greens, citrus fruits
• Deficiency causes scurvy, which shows as poor wound healing, bone problems, bleeding gums, poor immunity, etc.

Vitamin A (Retinol)

• Essential for vision, maintaining healthy skin, mucous membranes, epithelial tissue, immune function, reproduction, and growth
• Sources include liver, eggs, fortified milk, green or orange vegetables, fruits, deep orange/yellow/red.
• High dosages cause harmful effects.

Vitamin D

• Regulates calcium absorption, promotes bone growth/maintenance, and improves immunity
• Sources include sunlight exposure, fortified milk/margarine, egg yolks, fatty fish, liver
• Deficiency is related to rickets or osteomalacia (in adults)
  • Issues impacting the bones, development, and overall health

Vitamin E

• Acts as an antioxidant, protects cells from damage
• Sources include nuts, vegetable oils, seeds, leafy green vegetables, etc.
• Deficiency can lead to issues with nerve/muscle function and eye/skin
• High doses can potentially enhance the effects of anticoagulant medications

Vitamin K

• Assists with blood clotting functions and bone growth
• Sources include green leafy vegetables, cabbage/green vegetables, etc.
• Deficiency can lead to hemorrhaging
• High doses may interfere with anticoagulant medications associated medications
• Often synthesized in gut by bacteria

Fat-soluble vitamins

• Found in fats/oils of foods
• Absorbed into the lymph and then the blood
• Typically stored in the liver/body fat; accumulation can lead to toxicity
• Include vitamins A, D, E and K.

Note on Tables and Errors

• Some tables contained errors that have been corrected in these notes.

Test your knowledge on the essential roles of vitamins in biochemistry. This quiz covers their functions, sources, and importance in metabolism and overall health. Understand how coenzymes interact with enzymes and the consequences of vitamin deficiencies.