VITAMIN B-2 (Riboflavin)

General - water-soluble; the “yellow enzyme”;

• Bright yellow vitamin; imparts brilliance to urine of those consuming large quantities;
• First isolated as fluorescent material in milk whey & shown to be essential for rats;
• B-2 is manufactured by all plants & most bacteria & fungi, but not produced by animals;
• History: yellow enzyme recognized as vitamin in 1917; isolated in 1932; synthesized in 1935;

Nutrition

• Sources: widespread in whole foods; brewer’s yeast, dairy products, green leafy vegetables, fruit, grains, meats (esp. organ meats);
• Supplements: B-2, B-complex, multi-vitamin, multi-mineral-vitamin;
• Absorption from the upper portion of small intestine; freely circulates throughout body;
• Improved by: other B-complex factors & anti-oxidant vitamins C & E; better absorption if taken with meals;
• Antagonized by: alcohol; antibiotics;
• Stability: destroyed by light, UV or alkali; 10 - 30% lost in cooking; 60% lost in milling grains; 75% of B-2 in milk lost in making cheese;
• Storage: in endoplasmic reticula of all cells; elevated concentrations found in the liver, heart, kidneys; only minute amounts of B-2 are retained; daily replenishment is vital;
• Excretion: through urine;
• Interactions: oral contraceptives deplete B-2;

Functions of vitamin B-2

• Essential respiratory co-enzyme flavin adenine di-nucleotide (FAD) & flavin mono-nucleotide (FMN) in all cells; contributes to the capacity of several co-enzymes to accept & transfer hydrogen atoms or positive charges;
• Converts protein into usable energy;
• Helps cells use oxygen; prevents free radical damage by involvement with glutathione;
• Maintains good vision; helps prevent development of cataracts;
• Helps convert amino acid tryptophan to vitamin B-3; also activates B-6 & folic acid, affecting DNA synthesis, cell division & growth, that require B-3, folacin & B-6;
• Necessary for synthesis of glycogen;
• Maintains integrity of skin, nails & hair;
• Required for synthesis of: somatotrophic hormone (STH) that regulates growth; thyroxine that regulates metabolic rate; adrenocorticotrophic hormone (ACTH) that stimulates adrenal hormone production & growth; insulin that regulates energy metabolism;
• Enhances uptake of iron & B-6;
• Necessary to synthesize red blood cells in bone marrow;
• Controls growth & development of unborn foetus;
• Co-factor in breakdown of fatty acids for energy;
• Works together with vitamin A to maintain healthy mucous membranes;
• Important for providing energy necessary for tissue repair; important during pregnancy for normal development of foetus;
• May protect against oesophageal cancer;
• Functions helped by: other B-complex factors & antioxidant vitamins C & E;

Quantities

• Measurement: in milligrams (thousandths of a gram);
• Optimum: (SONA) average ranges from 1.8 to 2.5 mg/day;
• Individual optimum must be established for each individual; need increases with body size, energy requirement, exercise, protein consumption & metabolic rate; biochemical individuality dictates different needs for different people; exceptional need arises from gastrointestinal maladies, prescription antibiotics, oral contraceptives, alcohol, poor diet;
• Minimum: (DRI) set at 1.3 mg/day;
• Less than RDA: 34% of population, according to a U.S. government survey;
• Deficiency: one of most common vitamin deficiencies in North America;
• Results from inadequate diet; alcohol consumption; strenuous exercise; poor absorption;
• increased requirement; usually part of multiple (B-complex) deficiencies;
• At risk: elderly, alcoholics, athletes (esp. women); pregnant women; foetuses;
• Symptoms include: personality disturbances from faulty nerve cell metabolism; congenital malformations;
• Sub-clinical deficiency can manifest as: fatigue; digestive upset; hypertension; anorexia; lesions of lips, tongue, mouth, eyes, skin & genitalia; grainy, burning sensation of eyes & conjunctiva; difficult urination; baldness; sensitivity to light; oily, flaky skin; cataracts; vaginal itching; dizziness; increased effectiveness of cancerogens; growth retardation, birth defects; rapid involuntary eye movements (nystagmus); personality changes include hypochondriasis, depression, hysteria; reduced hand grip strength;
• Toxicity: for B-2 has not been recorded; harmless nutrient, even in doses 100x RDA;

Therapy with riboflavin

• Usual therapeutic dose ranges from 1.7 to 100 mg/day;
• Corrects conditions that result from riboflavin deficiency;
• Used to treat conjunctivitis, glaucoma & growth retardation;
• Prevent & reverse developing cataracts;
• Enhances iron absorption, protecting against anaemia;
• With B-6, B-2 may help in treatment of carpal tunnel syndrome;
• Boosts physical performance by making efficient energy production possible during intense physical activity & preventing free radical damage;