Why is iodine vital for our body?
Iodine is vital for good thyroid function, which in turn is essential for health. Iodine deficiency during pregnancy and early infancy can result in cretinism (irreversible mental retardation and severe motor impairments). In adults low iodine intake (or very high intakes) can cause hypothyroidism. Hypothyroidism can manifest as low energy levels, dry or scaly or yellowish skin, tingling and numbness in extremities, weight gain, forgetfulness, personality changes, depression, anaemia, and prolonged and heavy periods in women. Goiter, an enlarged thyroid gland visible between the Adam's apple and the collar bone, is often present. Hypothyroidism can also cause carpal tunnel syndrome and Raynaud's phenomenon. Hypothyroidism can lead to significant increases in cholesterol levels and homocysteine levels is implicated in about 10% of cases of high cholesterol levels. Correcting hypothyroidism can lead to a 30% drop in cholesterol and homocysteine levels.An iodine intake of less than 20 micro grams (µg) per day is considered severe deficiency, 20 -50 µg/day is considered moderate deficiency and 50-100 µg/day is considered mild deficiency.
Iodine is typically undesirably low (about 50 micrograms/day compared to a recommended level of about 150 micrograms per day) in UK vegan diets unless supplements, iodine rich seaweeds or foods containing such seaweeds (e.g. Vecon) are consumed. The low iodine levcls in many plant foods reflects the low iodine levels in the UK soil, due in part to the recent ice-age. About half the iodine consumption in the UK comes from dairy products. In the US iodised salt is widely used and some other foods are fortified with iodine. In Canada all table salt is iodized. The UK has no iodine fortification strategy for plant foods or salt.
Low zinc intakes exacerbate the effect of low iodine intake. Some otherwise healthful foods contain goitrogens - substances which can interfere with iodine uptake or hormone release from the thyroid gland. These foods are generally only a concern if iodine intake is low. Consumption of brassicas, such as cabbage, Brussels sprouts, broccoli and cauliflower, increase the requirements for iodine, especially if consumed raw. Soy beans, raw flaxseed, cassava (used in tapioca), sweet potatoes, lima beans, maize and millet also increase the requirements for iodine.
It is important not to over-consume iodine as it has a relatively narrow range of intakes that reliably support good thyroid function (about 100 to 300 micrograms per day). Someone consuming large amounts of iodised salt or seaweeds could readily overdo it. Excessive iodine has a complex disruptive effect on the thyroid and may cause either hypothyroidism or hyperthyroidism, in susceptible individuals, as well as increasing the risk read more
