Vitamins and Minerals- Squier Flashcards
Understand the definition of a vitamin. What are the water-soluble vitamins (5)? What are the fat soluble vitamins (4)
- Vitamins are small organic molecules that cannot be synthesized (except vitamin D). They serve as enzyme cofactors, antioxidants and other functions.
- Water-soluble: B vitamins, vitamin C, Biotin, Pantothenic (B5) acid and folic acid (B9).
- Fat-soluble: Vitamins A, D, E and K.
- **Excess intake causes toxicity.
What are the characteristics of water-soluble vitamins?
- Not stored.
- Regular dietary intake necessary.
- Non-toxic even in large quantities.
What is vitamin B9 and how does it contribute to metabolic reactions?
Folic acid (B9): transfers 1 carbon fragments in synthesis of amino acids. Prevents neural tube defects in fetus. •Sulfa drugs and cancer therapies target tetrahydrofolate because it is critical in DNA synthesis •Deficiency leads to megaloblastic anemia, neural tube defects and decrease in nucleic acid synthesis. •Causes: decreased dietary intake, alcoholism, poor absorption or those inhibitors listed above. •Vitamin B12 is needed to maintain tetrahydrofolate (FH4) pools needed for methyl transfer reactions.
What is vitamin B12 and how does it contribute to metabolic reactions (2)?
Functions: enzyme cofactor for the breakdown of odd-numbered fatty acids (methylmalonyl CoA mutase) and methionine synthesis (homocysteine methyltransferase).
What are the metabolic effects of vitamin B12 deficiency?
Deficiency leads to accumulation of odd-numbered fatty acids that get incorporated into membranes, leading to neurological abnormalities. Also can lead to secondary folate deficiency and thus megaloblastic anemia.
•Causes: low dietary intake, (vegans are at slight risk) ileum disease (crohn’s disease).
•Absorption: requires intrinsic factor (IF) to bind to B12 which then transports it to the ilium and stored in the liver.
What are the functions (7) of vitamin C and how do they relate to disease?
Functions: coenzyme in hydroxylation reactions critical in collagen biosynthesis, maintenance of CT and wound healing, reducing agent, absorption of dietary iron, antioxidant and free radical scavenger.
Deficiency: causes deficiency in collagen biosynthesis leading to scurvy (swollen & spongy gums, anemia, and muscle pain).
Causes: insufficient diet, elderly and alcoholics.
Collagen maturation function:
Ascorbate prevents the auto-oxidation of active site metals needed for the oxidation of proline and collagen cross-linking.
What is vitamin B6 and how does it contribute to metabolic reactions (4)?
- Precursor to PLP (pyridoxyl phosphate).
- Functions: enzyme cofactor required for glycogen phosphorylase, heme synthesis, amino acid metabolism and conversion of tryptophan to niacin.
- Deficiency leads to abnormal amino acid metabolism, secondary pellagra (inability to synthesize niacin) and microcytic anemia.
- Causes: women on oral contraceptives, alcoholics, elderly and treatment w/ isoniazid (tuberculosis treatment).
What is vitamin B1 and how does it contribute to metabolic reactions (3)?
Thiamine.
Functions: cofactor for enzymes (active form is thiamine pyrophosphate TPP) such as PDH, α-ketoglutarate dehydrogenase, transketolase.
•Key to catalyzing bond cleavage/formation of alpha ketols.
•Deficiency leads to decreased ATP production affecting nervous system, accumulation of lactate and pyruvate (lactic acidosis), decreases in NADPH
•Can lead to Beri-beri, wernicke’s encephalopathy and korsakoff’s.
•Causes: alcoholism, cancer, dietary intake and liver disease.
What is vitamin B3 and how does it contribute to metabolic reactions (3)?
Niacin.
Functions: cofactor for oxidase and dehydrogenase enzymes (active forms are NAD+ and NADP+), repair of UV light damage in DNA.
Deficiency: causes pellagra.
Causes: dietary intake, protein deficiency (tryptophan), vitamin B6 and PLP deficiency.
What is vitamin B2 and how does it contribute to metabolic reactions (2)?
Riboflavin.
Functions: cofactors for oxidase and dehydrogenase enzymes (active forms are FAD & FMN).
Deficiency causes ariboflavinosis.
What is Biotin and how does it contribute to metabolic reactions (4)?
Functions: coenzyme for carboxylation reactions such as pyruvate carboxylase, acetyl CoA carboxylase, propionyl CoA carboxylase and branched-chain amino acid metabolism.
Deficiency may cause dermatitis.
Causes: long-term antibiotic therapy and consuming large amounts of egg whites (contain avidin which binds to biotin and prevents absorption).
What is Pantothenic acid (B5) and how does it contribute to metabolic reactions (2)?
Functions: transfer of acyl groups as component of CoA and component of fatty acid synthase.
Deficiency leads to burning foot syndrome.
What are the characteristics of the fat-soluble vitamins?
E, K, A, and D.
•Stored in liver and adipose tissue.
•Difficult to absorb and excrete.
•Excess intake causes toxicity (due to capacity for storage).
What are the functions of vitamin A (5)?
Family of compounds (retinoids) including: retinol, retinal, retinoic acid and β-carotene.
Functions:
1. Retinal is important for vision.
o Deficiency can lead to blindness.
2. β-carotene is an antioxidant.
3. Retinoic acid is a steroid hormone & is important for epithelial cell differentiation.
o Treatment for severe acne.
4. Retinol & retinal are important in reproduction & fertility (spermatogenesis & placental development).
5. Growth of bones & teeth.
What are the functions of vitamin D (2)? What is vit D deficiency?
Functions: maintain Calcium and phosphate (Bone) levels by increasing reabsorption of bone.
Deficiency: causes low calcium levels and impaired bone mineralization (rickets in kids, osteomalacia in adults), hypocalcemia and hypophosphatemia.
Causes: dietary intake, inadequate sunlight, renal and liver disease and fat malabsorption.
***Most toxic vitamin and can cause hypervitaminosis D (nausea, vomiting, muscle weakness, thirst and hypercalcemia).
