Review of Basic Nutrition

VITAMINS Nutrients for humans

RENI

Vitamins

Vitamers

Water-soluble vitamins Fat-soluble vitamins Requiring processing in vivo for activity

Major actions

Vs minerals Role of vitamins

Energy-yielding dietary components  carbohydrates  fats  proteins Essential and non essential amino acids  proteins Essential unsaturated fatty acids  fats Minerals [including trace minerals] Vitamins Recommended energy and nutrient intake [Philippines] Vs RDA [recommended dietary allowances] Vs DRI [dietary reference intakes]  AI [adequate intake]  UL [tolerable upper intake level]: highest level of daily intake that is likely to pose no risk of toxicity  EAR [estimated average requirement] Organic substances that must be provided in small quantities from the environment because  they cannot be synthesized de novo in humans or  their rate of synthesis is inadequate for the maintenance of health [eg, production of nicotinic acid [niacin] from tryptophan] Exception: endogenous synthesis of Vitamin D under the influence of UV light Analogs of vitamins  as when occur in more than one chemical form [pyridoxine, pyridoxal, pyridoxamine]  as precursor [carotene for vitamin A] Frequent consumption is needed to maintain saturation of tissues Potential for serious toxicity Activation by  phosphorylation: thiamine, riboflavin, nicotinic acid, pyridoxine  coupling to purine or pyridine nucleotides: riboflavin, nicotinic acid  Water-soluble vitamins participate as co-factors for specific enzymes  Vitamins A &D behave more like hormones and interact with specific intracellular receptors in the target tissues  Inorganic nutrients  Used for the prevention and treatment of specific deficiency 

states or where the diet is known to be inadequate Maybe prescribed to prevent or treat deficiency but not as

1



Vs health supplements

dietary supplements Use as general ‘pick-me-ups’ is of unproven value and, in the case of preparations containing vitamin A or D, may actually be harmful if patients take more than the prescribed dose. The ‘fad’ for mega-vitamin therapy with water-soluble vitamins, such as ascorbic acid and pyridoxine, is unscientific and can be harmful

Dietary supplements, food supplements, functional foods, nutraceuticals

WATER-SOLUBLE VITAMINS Vitamin Vitamin C Ascorbic acid Dehydroascorbic acid

Deficiency Scurvy: gingivitis and gum bleeding, petechiae [rare]

Toxicity Kidney stone [due to excessive excretion of oxalates]

Heat labile Alkali-labile

Sources Guavas, citrus, strawberry, tomatoes, potatoes,

Use/s, remarks *Claims to ameliorate colds or promote wound-healing have not been proved; *Lower levels in smokers [because of increased metabolic turnover]; *Increased requirements in infectious disease, post-surgery *Antioxidant [to protect natural flavour and color of food]

*Usefulness of megadoses lacks evidence *Promotes intestinal absorption of iron [non-heme to ferrous] No evidence of value: *paramino-benzoic acid, *biotin, *choline, *inositol, *pantothenic acid

B vitamins          

Thiamine Riboflavin Nicotinamide Pyridoxine Pantothenic acid Biotin Folic acid Cyanocobalamin Choline Inositol



Paraaminobenzoic acid

Vitamin B1 Thiamine

*Beriberi [NS, CVS] *Wernicke’s encephalopathy, Korsakoff’s psychosis esp in chronic alcoholics

Vitamin B6 Pyridoxine

Rare, but may occur during isoniazid

Anaphylaxi s with parenteral prep

Unpolished rice, meat

Deficiency: initially with parenteral prep followed by oral thiamine

Meat, liver, soy beans, whole

*With isoniazid therapy *Antidote for INH overdose 2

Pyridoxal PO4

therapy, characterized by peripheral neuritis

grains, cereals

Vitamin B12 Cyanocobalamin Hydroxocobalamin Mecobalamin Folic acid Folinic acid

*Megaloblastic anemia *Nervous system

Microorganis ms; legumes

*Megaloblastic anemia *Neural tube defect *With use of trimethoprim, methotrexate, oral contraceptives Pellagra [dermatitis, diarrhea, dementia]

Fresh greens; liver, yeast

*For megaloblastic anemia; *Pregnant; *Folinic acid [calcium folinate] used in cytotoxic therapy

Liver, meat, fish, poultry, whole grains, nuts, legumes Milk, cheese; organ meats, egg; green leafy vege; whole grains

*Inhibits synthesis of cholesterol and triglycerides; *Nicotinamide does not cause vasodilation

Heat-labile

Vitamin B3 Nicotinic acid Nicotinamide

Vitamin B2 Riboflavin Flavin adenine dinucleotide

Sore throat, glossitis, cheilosis, dermatitis, anemia, neuropathy

*High doses given in hyperoxaluria; *Also used in sideroblastic anemia; *May have benefit in PMS [600]: Betacarotene, carotene, cryptoxanthin >> Vit A Lutein, lycopene

3

Vitamin D Ergocalciferol [calciferol, D2]; Colecalciferol [D3]; Alfacalcidol; Calcitriol

Vitamin E Alpha tocopherol; Alpha tocopheryl acetate

Vitamin K Phytomenadione [K1] Menadiol NaPO4 Menaquinone [K2]

Rickets, osteomalacia

*Protean manifestations [CNS, muscular, atherosclerosis];

*In children with low VIt E, neuromuscular abnormalities Bleeding

Anorexia, headache nausea, vomiting, diarrhea, polyuria, sweating, raised Ca and PO4 in serum and urine

Diarrhea, abdominal pain, pruritus, rash

Hemolytic anemia, kernicterus

*Vit D defieciency caused by malabsorption or chronic liver disease requires up to 1mg daily; *Hypocalcemia of hypoparathyroidism requires doses of up to 2.5mg daily

Meat

*Alfacalcidol or calcitriol in patients with renal impairment [failed hydroxylation to active form]; *Calcitriol for postmenopausal osteoporosis *Tried for various conditions but little or no scientific evidence of its value; *Little evidence that oral supplements are essential in adults *Antioxidant *Necessary for the prod of blood clotting factors [Factor II, VII, IX, X] and proteins necessary for normal bone calcification; *Oral coumarins act by interfering with Vit K metabolism in the liver and their effects can be antagonized by giving Vit K; *Neonates are relatively deficient in Vit K

4

IMMUNOMODULATORS Immunosuppressives

Glucocorticoids  Prednisone  Prednisolone  Methylprednisolone Calcineurin imhibitors  Ciclosporin  Tacrolimus Antiproliferative and antimetabolic drugs  Sirolimus  Everolimus  Azathioprine  Mycophenolate sodium  Mycophenolate mofetil Antibodies  Antithymocyte globulin  Antilymphocyte globulin  Monoclonal antibodies  AntiCD3 monoclonal antibodies 5

 Anti IL2 receptor antibodies  Infliximab Immunostimulants

Levamisole BCG Thalidomide Recombinant cytokines  Interferons [IF alfa 2A, IF alfa 2B, peginterferon alfa 2A]  Interleukins [IL2]

Glucocorticoids

Immunosuppressant  decrease size and content of lymph node and spleen  cytotoxic to some T-cells  no toxic effect on myeloid tissues Anti-inflammatory Uses  First line for both solid organ and hematopoietic stem cell transplant  Rheumatoid arthritis, idiopathic thrombocytopenic purpura

Ciclosporin

Calcineurin inhibitor Metabolized by P450, implications for drug interactions Uses  For kidney, pancreas, liver, heart transplant  Graft vs host rejection  Autoimmune diseases  For psoriasis 10 to 100 times more potent than ciclosporin Similar mechanism of action, uses, and toxicity as ciclosporin Ointment for psoriasis and atopic dermatitis

Tacrolimus

Sirolimus

Blocks response of T-cells to cytokines

Mycophenolate mofetil, mycophenolate sodium

Active: mycophenolic acid For solid organ transplant For refractory rejection

Interferon

Uses    Uses  

Interleukin

Levamisole

for melanoma, renal cell ca, CML with ribavirin for hepatitis C for multiple sclerosis For metastatic renal cell carcinoma Malignant melanoma

With fluorouracil for colorectal carcinoma 6

BCG Thalidomide

For superficial bladder cancer For multiple myeloma, erythema nodosum leprosum, lupus erythematosus skin manifetations

7