Iodine is combined with the amino acid tyrosine in order to manufacture active thyroid hormone. In fact, this is the primary function of iodine in the body. Although iodine’s activity is essentially linked to thyroid function, a deficiency in this mineral can lead to a wide range of symptoms and disorders. This is due to the fact that thyroid hormones either directly or directly impact on so many aspects of human biochemistry and physiology, such as cellular metabolism, body temperature, growth and development, reproductive function, breast health, hair and skin health, etc. A lack of dietary iodine may lead to goiter, which manifests as an enlargement of the thyroid, with the associated swelling at the base of the neck. The utilisation of iodine in thyroid function can be impaired by foods known as goitrogens (i.e. cabbage, cauliflower, Brussels sprouts, soybeans, cassava, peanuts, millet, turnips, kale, pine nuts, spinach, mustard seed, rutabagas, pears and peaches). It appears that the goitrogenic activity of these foods is usually deactivated by cooking them.

Please note: While deficient iodine can reduce thyroid hormone activity, very high iodine intake (i.e. more than 750-1000ug per day) may actually reduce thyroid hormone synthesis and secretion (see Contraindications/Cautions below).


Although thyroid hormone activity impacts on so many aspects of health, its primary role is controlling the rate of cellular metabolism. The basal metabolic rate not only influences the production of energy within cells, but also reflects the rate at which fats are burned to produce energy. As a result, basal metabolic rate – and thus, thyroid function – is a critical issue with respect to body fat concentrations. Not surprisingly, those with an under-active thyroid (hypothyroidism) will be more prone to obesity. Iodine supplementation, in and of itself, will not necessarily treat obesity or increase the rate of fat metabolism; however if one is iodine deficient, supplementation may allow for more efficient thyroid function (and thus, more efficient fat metabolism).


Iodine’s relationship with cellular metabolism is ultimately influential to not only tissue growth, also one’s overall biochemical and physiological function. Iodine also influences cellular differentiation and the synthesis of proteins. All these aspect are critical to normal, healthy growth and development. As such, ensuring proper iodine status is very important in babies and children, as well as during pregnancy.


Research indicates that iodine supplementation can be an effective tool in the treatment of fibrocystic breast disease (FBD), which manifests as benign cysts which cause pain and swelling in the breasts. Scientists have postulated that a lack of iodine in breast tissue may make the breast cells more sensitive to the hormone oestrogen, which in turn, triggers the cystic growth

Please note: The dosages of iodine used in these successful FBD clinical trials were far in excess of amounts that are suitable unless under the care of a physician; however lower doses which ensure adequate iodine status may still be of value in maintaining breast health.

•        Hypothyroidism (under-active thyroid)

•        Growth and development

•        Weight control (if hypothyroid)

•        Fibrocystic breast disease

•        Hyperthyroidism (over-active thyroid) [when used in very high doses]

Please note: very high doses of iodine should only be used for hyperthyroidism on the advice a, under the strict monitoring of a physician (see Contraindications/Cautions below)

Typical Supplemental Dosage Range

• 150-500ug per day

EC RDA (adults)

• 150ug

Common Supplement Forms/Sources

•        Kelp

•        Potassium iodide

•        Sodium iodide

Common Food Sources

•        Iodised salt

•        Seaweed (especially kelp and dulse)

•        Cod

•        Haddock

•        Shellfish

•        Garlic

•        Asparagus

•        Lima beans

•        Mushrooms

•        Soybeans

•        Spinach

Contraindications/Cautions/lnteractions/Toxicity Concerns

•        In general, daily doses exceeding 1500ug (1.5 milligrams) are not recommended unless under strict monitoring of a physician; doses exceeding lOOOug per day are not recommended unless the advice of a physician or qualified healthcare practitioner; people with hypothyroidism sho not exceed 750ug of iodine per day unless under the supervision of a physician. Research indi that intake of iodine in excess of 1500ug per day may actually reduce thyroid hormone activii thought that in people with hypothyroidism, reduced thyroid activity may occur in rare instar with daily doses as low as 750ug.

•        High doses of iodine may cause a skin reaction resembling acne.

•        Evidence of interactions with any medication appears to be lacking for doses below 600ug pe However, in those who take thyroid hormone medication, administration of high doses of iod not recommended unless on the advice and under the strict monitoring of a physician.

High doses of iodine are not recommended in patients taking lithium carbonate, unless on th< advice and under the strict monitoring of a physician.

Agents/Factors Which Deplete Levels, Impair


Pine nuts*


Mustard seeds*




Absorption and/or Inhibit Activity


Pine nuts*


Mustard seeds*




•   It appears that the goitrogenic activity of this food is usually deactivated by cooking.

Possible Signs/Symptoms Associated with Deficiency

•        Hypothyroidism (under-active thyroid)

•        Goiter

•        Cretinism

•        Impaired growth

•        Impaired mental development

•        Miscarriage

•        Foetal abnormalities

•        Increased risk of infant mortality

•        Obesity

•        Fatigue

•        Depression

•        Irregular menstruation

•        Heavy menstrual bleeding

•        Infertility

•        Dry, scaly skin

•        Hair loss

•        Brittle nails

•        Weak muscles

•        Constipation

•        Stiff joints

•       Excessive sensitivity to cold

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