Nutrition and Supplements
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Nutrition and Supplements


Introduction

Vitamin: A complex organic substance required in the diet in small amounts, the absence of which leads to a deficiency disease.

  • Vitamins and minerals are micronutrients that generally cannot be synthesized by the body; their dietary intake must be between the extremes of low (causing clinical deficiency disease) or high (causing overdose toxicity as with hypervitaminosis A or iron tablet ingestion).
  • The lipid-soluble vitamins A, D, E, and K are absorbed with fat, so main- tenance of adequate levels requires normal intestinal fat absorption.
  • A vitamin is defined as an organic compound needed in small amounts to foster metabolic integrity, usually as a cofactor in enzyme reactions;

vitamin B complex, several vitamins that traditionally have been grouped together because of loose similarities in their properties, their distribution in natural sources, and their physiological functions, which overlap considerably. All the B vitamins, like vitamin C, are soluble in water, in contrast to the fat-soluble vitamins A, D, E, and K.

Most of the B vitamins have been recognized as coenzymes (substances that participate with enzymes in accelerating the interconversion of chemical compounds), and they all appear to be essential in facilitating the metabolic processes of all forms of animal life. The complex includes pantothenic acid, niacin, biotin, folic acid, riboflavin (vitamin B2), thiamin (vitamin B1), vitamin B6, and vitamin B12 (cobalamin). The compounds carnitine, choline, lipoic acid, inositol, and para-aminobenzoic acid perform analogous functions in animals and have been included among the B vitamins by certain authorities.

Vitamins Group

Fat-soluble vitamins

Vitamins A, D, E and K. These are:

  • Stored in the liver
  • Not absorbed or excreted easily
  • Can be toxic in excess (particularly A and D)

Water-soluble vitamins

The B-group vitamins and vitamin C. These are:

  • Not stored extensively
  • Required regularly in the diet
  • Generally non-toxic in excess (within reason).
  • All B vitamins are coenzymes in metabolic pathways
Vitamin functions, Deficiency diseases, and high-dose Therapies
Vitamin Name Functions Deficiency Disease Therapy
A Retinols, β-carotene Retinal pigment, signal transduction, antioxidant Night blindness, dry eyes (xerophthalmia) with corneal ulcers and blindness, hyperkeratosis (scaly skin) Contraindicated—causes increased intracranial pressure
D Calciferol Calcium absorption/excretion, bone formation Rickets: poor bone mineralization (osteomalacia) and formation (bowed legs) Vitamin D-resistant rickets
E Tocopherols Antioxidant Neurologic symptoms (rare); anemia Common in skin care but not proven effective
K Phylloquinone Blood clotting and bone formation; made by intestinal flora Normal newborns; bleeding, and bone changes (stippled epiphyses, short nose) Routine nursery administration, rare inborn errors
B1 Thiamin Coenzyme for pyruvate dehydrogenase (PDH), other enzymes Beriberi: burning sensory neuropathy, cardiac failure, edema; Wernicke-Korsakoff dementia in alcoholics Leigh disease and other mitochondrial disorders with PDH deficiency
B2 Riboflavin Coenzyme in redox reactions; precursor to flavoproteins FMN, FAD Photophobia, stomatitis (irritation at corners of mouth, lips, and tongue), and anemia Mitochondrial enzyme deficiencies having flavin cofactors
Niacin Coenzyme in redox reactions as part of NAD(P)/NAD(P)H Pellagra—photosensitive dermatitis, psychosis Hartnup disease—defect in neutral amino acid including tryptophan; effective at raising HDL51
B6 Pyridoxine Coenzyme for amino acid, glycogen, and steroid metabolism Convulsions; peripheral nerve pain in slow metabolizers with P450 variants and alcoholics Infantile convulsions of unknown cause; homocystinuria
Folic acid Coenzyme for one-carbon transfer as in nudeotide synthesis Megaloblastic anemia, folate inhibitors Megaloblastic anemia; preconceptional therapy to lower risk for neural tube defects
B12 Cobalamin Coenzyme for one-carbon transfer and in folate metabolism Pernicious anemia with neuromuscular symptoms Methylmalonic acidemia, folate metabolism defects
Pantothenic acid Part of fatty acyl synthase complex, fatty acid synthesis Rare, usually with other vitamin deficiencies— irritability, depression, and cramps
Biotin Coenzyme for carboxylation reactions in gluconeogenesis, fatty acid synthesis Metabolic acidosis, hair loss, skin rashes, and failure to thrive Biotinidase deficiency, propionic acidemia
C Ascorbic acid Collagen proline, lysine hydroxylation, antioxidant, enhances iron absorption Scurvy—poor wound healing, bone tenderness with rib swelling (rachitic rosary), gum disease with tooth loss, hemorrhage with bruising, and nosebleeds Wound healing after surgery; not effective for URI in controlled trials
Essential Macro-minerals
Mineral Functions Deficiency and Toxicity Diseases Sources
Na++ Sodium Main cation of extracellular fluid; water/salt balance; neuromuscular functions Hypotonic dehydration in children; renal disorders; salt-wasting in chronic illness; hypertension Table salt
K+ Potassium Main cation of intracellular fluid; water/base balance, neuromuscular functions Muscle weakness, confusion, metabolic alkalosis; cardiac arrest, intestinal ulcers Vegetables, fruits (bananas), and nuts
Cl− Chloride Fluid/electrolyte balance; gastric fluid Prolonged vomiting (as with pyloric stenosis), causing hypochloremic alkalosis Table salt
Ca++ Calcium Constituent of bones, teeth; regulates neuromuscular function Rickets (soft, fragile bones—osteomalacia—and bony deformities) in children; bone pain and osteoporosis in adults; and muscle contractions (tetany); renal disease Dairy products, beans, and leafy vegetables
P Phosphorus Constituent of bones, teeth; high-energy intermediates and nucleic acid at cellular level Rickets in children, osteomalacia in adults; bone loss by stimulating secondary hyperparathyroidism Phosphate food additives
Mg++ Magnesium Constituent of bones, teeth; enzyme cofactor (kinases, etc) Muscle contractions; muscle dysfunction with decreased reflexes and respiratory depression Leafy green vegetables
Essential Microminerals
Mineral Functions Deficiency and Toxicity Diseases Sources
Cr Chromium Potentiates insulin Impaired glucose tolerance Meat, liver, grains, nuts, and cheese
Co Cobalt Constituent of vitamin B12
Cu Copper Constituent of oxidases, promotes iron absorption Similar to scurvy; kinky hair and connective tissue defects in Menkes disease; cerebral and liver toxicity in Wilson disease Liver
I Iodine Constituent of thyroid hormones Hypothyroidism, producing low muscle tone, porcine features, and developmental retardation in children (cretinism); enlarged thyroid (goiter), lethargy, myopathy and lower leg swelling (myxedema) in adults; hyperthyroidism with protruding eyes (exophthalmos), tachycardia, and goiter Iodized table salt, seafood
Fe Iron Constituent of heme cofactor for hemoglobins, cytochromes Anemia (hypochromic, microcytic) with pallor, fatigue, and heart failure; iron overload (hemosiderosis in cells) with liver and heart failure; those with hereditary hemochromatosis more susceptible
Se Selenium Constituent of glutathione peroxidase Subtle protein-energy malnutrition; hair loss, dermatitis, and irritability Plants, meat
Zn Zinc Cofactor for diverse enzymes, constituent of zinc finger DNA-binding motifs of signal transduction proteins Acrodermatitis enterohepatica with hair loss, skin rashes, bowel malabsorption; decreased taste and smell acuity; gastrointestinal irritation, vomiting
F Fluoride Can be incorporated into bones and teeth for increased hardness Dental caries, osteoporosis; al fluorosis (spotting) Drinking water where added

*Aluminum, arsenic, antimony, boron, bromine, cadmium, cesium, germanium, lead, mercury, silver, and strontium are known to be toxic in excess.



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