CANCER of the thyroid glands is rare, and affects three times as many women as men. However, it can be caused be consuming too much of the mineral iodine, usually in the form of supplements.
The thyroid glands convert iodine – usually from food, but sometimes supplements – into thyroid hormones.
These hormones, triiodothyronine and thyroxine, help keep cells and the metabolic rate healthy.
According to the US Office of Dietary Supplements it’s important for proper bone and brain development during pregnancy and infancy.
You can get iodine from food sources, such as sea fish and shellfish.
It can also be found in plant foods – such as cereals and grains – but the level depends on amount of iodine in the soil.
It’s recommended adults get 0.14mg a day.
The NHS suggest that it’s possible to get enough iodine from dietary sources.
However, some people may need to take supplements.
Indeed, it’s thought 40 per cent of the worldwide population is at risk of iodine deficiency.
Symptoms of this include lethargy, feeling cold, difficulty concentrating and unusual weight gain.
Reasons for deficiency might include bromine exposure, not having enough iodine-rich foods, soil depletion and drinking fluorinated water.
The Department of Health recommend that sticking to 0.5mg or less a day of iodine supplements is unlikely to be dangerous.
However, taking high doses of the mineral for long periods could harm the thyroid glands.
It can also cause a condition called hypothyroidism – when the thyroid produces too little thyroid hormone – and which is usually associated with deficiency.
A 2012 study published in the American Journal of Clinical Nutrition found that participants who consumed 400mg in iodine supplements a day developed the condition.
According to the US Office of Dietary Supplements it can cause thyroid gland inflammation and thyroid cancer.
They state: “Getting a very large dose of iodine (several grams, for example) can cause burning of the mouth, throat, and stomach; fever; stomach pain; nausea; vomiting; diarrhoea; weak pulse; and coma.”