Vitamins and Minerals: Functions, Sources, and Deficiencies

Vitamins and Minerals

Soluble Vitamins

Vitamin C: Protects, regulates, and facilitates chemical processes of other enzymes. Its main function is the formation of collagen, facilitates the absorption of iron, protects vitamin A and E from oxidation, and regulates cholesterol metabolism. Sources: green vegetables, citrus fruits, tomatoes. Deficiency: scurvy, irritability, bone pain, easy bleeding, poor healing. Toxicity: gastric irritation, kidney stones, false positive tests for fecal occult blood or glucosuria.

Vitamin B1 (Thiamine): Important coenzyme in the metabolism of carbohydrates. Sources: meat, grains, legumes. Deficiency causes: alcoholism, dialysis, diet high in carbohydrates. Beriberi, Wernicke's encephalopathy.

Vitamin B2 (Riboflavin): Combines with phosphoric acid to be part of a coenzyme needed for growth and synthesis of adrenal corticosteroids. Sources: milk, whole grains, green vegetables. Deficiency: cheilosis, glossitis, seborrheic dermatitis, corneal vascularization.

Vitamin B6 (Pyridoxine): Coenzyme in metabolic processes of amino acids, a cofactor in carbohydrate and lipid metabolism, facilitates the release of liver and muscle glycogen. Sources: meats, grains, eggs, cereals, green vegetables, legumes. Deficiency: alcoholism, drug interactions, oral contraceptives, microcytic hypochromic anemia, dermatitis, convulsions. Toxicity: may decrease the levels of levodopa and phenytoin. Large doses for long periods cause sensory neuropathy and ataxia.

Biotin: Carboxylation enzyme cofactor for substrates: pyruvate, acetyl-CoA, propionyl-CoA, beta-methylcrotonyl-CoA, important in metabolism of carbohydrates and lipids. Sources: organ meats, egg yolks, milk, fish, nuts. Deficiency: exfoliative dermatitis, alopecia, muscle pain, anorexia, anemia.

Vitamins therapeutic use: restoring deficiencies.

• Thiamin: beriberi
• Riboflavin: dermatopathies, stomatitis, glossitis, and anemia
• Pyridoxine: central and peripheral neuropathy
• Niacin (Nicotinic acid): Pellagra
• Cyanocobalamin: pernicious anemia
• Folic acid: Megaloblastic anemia
• Vitamin A: xerophthalmia, keratomalacia, nyctalopia
• Vitamin D: Rickets, osteomalacia
• Vitamin K: hemorrhagic syndrome
• Vitamin E: antioxidant role
• Vitamin C: Scurvy

Minerals

Minerals make up 4% of total body weight. Their tasks are varied: essential for normal cellular activity and osmotic properties of body fluids. Most minerals have wide distribution in foods. Deficiencies can occur with vegetarian diets or prolonged total parenteral nutrition.

Magnesium: Activates many enzyme systems, is a cofactor in oxidative phosphorylation and thermoregulation. Hypomagnesemia: increased neuronal excitability and neuromuscular transmission. Hypermagnesemia: vasodilation, bradycardia, respiratory depression, and decrease of tendon reflexes.

Phosphorus: Necessary for the utilization of vitamin B complex, is involved in the formation of bones, teeth, and body fluids.

Trace Elements

Chromium: Cofactor in the secretion of insulin. Excess chromium is toxic.

Cobalt: Cofactor of vitamin B12. Excessive doses produce polycythemia.

Normal Low Sodium Diet

In a normal diet, consumption is 10 to 15 g of sodium chloride (common salt), equivalent to 3900 to 5900 mg of sodium. (1 g of sodium chloride (common salt) = 390 mg sodium). Sodium in food comes from the standard content in the food itself, which is the sodium of incorporation; and sodium chloride (common salt) added at the table or in cooking is sodium addition. A normal low sodium diet contains 1,500 to 2,000 mg of sodium per day (equivalent to a maximum of 5 grams of sodium chloride, common salt per day).