The World Health Organisation recommends that the level of Iodine in Urine should be between 100 and 200 μg per Litre.
Low iodine level can be corrected by:
1: lodised Salt (in moderation if you don’t have blood pressure problems). This is the green packet labelled “iodised salt” on the supermarket shelf near rock salt, sea salt, table and plain or cooking salt, which are all too low in iodine to fix the problem. Replace the other types of salt in your pantry so that you always use iodised salt.
2: Kelp (seaweed) 1.0 to 1.2 g tablets/capsules containing 150 μg of iodine (equivalent); take one per day. You can buy these from the Chemist, Supermarket or a Health food store. Try to get a brand that has the amount of iodine per tablet marked on the container.
3: Multivitamin Capsules Containing 150 μg of Potassium Iodide (check on the side of the Bottle for the amount as some only have 30 μg).
Iodine is found in increased amounts in spinach, seaweed products like dried seaweed, sushi or miso soup and in salt water fish; BUT you should avoid large tuna (tinned tuna is OK), sword fish and marlin as these have TOO MUCH MERCURY (3 serves per week can produce clinical mercury poisoning).
To avoid thyroid enlargement due to low iodine, some form of iodine supplement is needed long term. Children and teenagers do not need Kelp tablets but should use iodised salt in moderation every day.
Correcting low iodine levels will probably not improve a large goitre or make big or calcified thyroid nodules get smaller, but will help with diffuse goitres in teenage years, and may prevent early goitres from getting rapidly worse. Iodine supplementation is advised and is safe in pregnancy and lactation, and may assist in foetal brain development.
High levels of iodine are OK in the short term but can produce overactive or underactive thyroids in some older patients. X-ray contrast dyes, betadine mouth wash and some herbal remedies and the heart drug Amiodarone are examples of this group.
Some foods contain thiocyanates naturally which if eaten regularly as a staple food (i.e. every day) can cause thyroid enlargement; these foods are called goitrogens. Occasional (weekly) serves are OK.
This list includes:
Turnips, swedes, brussel sprouts, cabbage, bamboo shoots, cassava, and maize.