IODINE (I)

General - trace element; anti-goitre (thyroid) element; “metabolic rate” element;

• Iodine content of foods reflects I content of soil and/or water:
• Healthy adult body contains about 15 - 30 mg of iodine;
• Major present source of iodine is iodized table salt; commercial foods made with non-I salt;
• History: iodine discovered in 1811; seaweed used to treat goitre in 1816; essentiality for humans established in 1850; iodine found in thyroid gland in 1895; cabbage found to produce goitre in rabbits in 1928; iodized salt available nationwide by 1940; thyroid hormones identified by 1953;

Nutrition

• Sources: sea weeds, esp. dulse & kelp; sea food, thyroid gland; iodized salt, food grown on iodine-rich soil;
• Supplements: kelp, potassium iodide, potassium gluconate, multi-mineral, multi-mineral-vitamin formulations;
• Absorption from stomach, upper small intestine & throughout entire intestine;
• Antagonized by: containing-containing cruciferous vegetables (cabbage, broccoli);
• Storage: 75% is in the thyroid gland; also concentrated in ovarian tissue; iodine-containing hormone circulates throughout entire body; removed by salivary glands & recycled; body stores several months’ supply of iodine;
• Excretion: removed through mother’s breast milk; excreted through kidneys;
• Metabolism: increased need for I on diets high in cabbage, Brussels sprouts, turnips, broccoli, cauliflower; metabolism of iodine in thyroid needs vitamin B-2; copper & zinc necessary for conversion of thyroxin into active hormone (triiodothyronine);
• Interactions: bromide, thiocyanate, perchlorate compete with iodine for transport;

Functions of iodine

• Intimately associated with thyroid function, through its presence in the thyroid hormones thyroxin (76% iodine) & triiodothyronine — iodine-containing amino acids that control the metabolic rate of the entire body;
• Stabilizes & controls virtually all biochemical reactions in the body;
• Appears to control calcium & phosphorus metabolism, as well as starch metabolism;
• Helps assimilate calcium, silicon, iron, chlorine, magnesium, manganese & other elements;
• Regulates growth, development & basal metabolic rate; essential for reproduction;
• Diiodothyronine may regulate ovary functions;
• Important for both physical and mental development;
• Can increase metabolic rate by as much as 30% for 6 days by a single dose;
• Increases oxygen uptake & body temperature, heat loss & loss of body tissue;
• Helps metabolize excess fats;
• Necessary for protein synthesis;
• Necessary to convert carotene into vitamin A;
• Improves absorption from intestine of carbohydrates needed for energy;
• Helps provide the metabolic energy necessary for detoxifying metabolic & environmental toxins in the tissues throughout the body;
• Enhances performance of all glands & organs in the body;

Quantities

• Measurement: micrograms;
• Optimum: (SONA) not yet set;
• Individual optimum needs to be determined for each individual case;
• Minimum: (DRI) set at 150 μg/day;
• Less than RDA: rare in affluent countries, because of use of iodized salt; common around the world;
• Deficiency from iodine-deficient food supply; may result from salt-restricted diet used to treat high blood pressure; diet high in commercially processed foods (non-iodine salt);
• Symptoms include: lowered metabolic rate, improper cell growth & differentiation, impaired mental processes, mental retardation, deafness; lowered vitality; inability to think clearly; low resistance to infections; loss of control of mouth (drooling); defective teeth, slow development of sexual organs; impotence, sterility; cold hands & feet; hypoglycaemia;
• Deficiency of iodine linked to breast cancer; oestrogen in absence of iodine speeds abnormal, precancerus breast cell growth (dysphasia);
• Goitre: swollen neck from enlargement of thyroid gland; fatigue, susceptibility to colds, gain weight easily; deficiency during pregnancy: cretinism in the newborn;
• Toxicity: less than 2,000 mg of elemental iodine can be fatal; more than a few mg/day may lead to acne; more than 50 mg/day may cause reversible inflammation of salivary (parotid & submaxillary) glands;
• Symptoms include metallic taste & sores in mouth, swollen salivary glands, diarrhoea & vomiting;

Therapy with Iodine

• Usual therapeutic dose is 100 - 1,000 mg/day;
• Alleviates symptoms of deficiency, including goitre;
• Has been used to relieve pain and soreness associated with fibrocystic breasts, that may be a symptom of iodine deficiency;
• Diiodothyronine, plus magnesium, copper & manganese relieves sore & heavy breasts & normalizes vaginal mucus; may also help keep cholesterol from forming, keep skin unwrinkled & keep breasts soft;
• 100 mg/day of iodine as potassium iodide for 7 to 14 days can protect from thyroid cancer due to uptake of radioactive iodine from nuclear fallout, by saturating thyroid tissue;
• Used in mucus-loosening (mucolytic) agents available by prescription;
• Externally, used to disinfect non-treated country water; excellent external antiseptic for wounds;