Iodine

How much do you need daily?

Adults need 140 micrograms of iodine per day. Most people should be able to get all the iodine they need by eating a varied and balanced diet.

Are we getting enough?

According to the UK Scientific Advisory Committee on Nutrition (SACN), there is public health concern that iodine intakes have become marginally adequate or actually inadequate for particular needs, especially during adolescence, reproduction and gestation and development.

The 2018 National Diet and Nutrition Survey found low levels of iodine in nine per cent of children aged 4 to 10 years, 12 per cent of children aged 11 to 18 years, 14 per cent of adults aged 19-64 and eight per cent of adults aged 65 years and over.

Why do we need it?

Iodine is a trace element found in seawater, rocks and some types of soil. In the human body, it is essential for the production of the hormones thyroxine and triiodothyronine in the thyroid gland – these regulate how energy is produced and used up in the body. Too much or too little iodine can throw our metabolism off balance. Iodine is also necessary for the development of the nervous system and cognitive abilities in infancy and childhood.

The amount of iodine in plants depends on how much iodine is in the soil in which they grow (just as the levels in meat, chicken, eggs and dairy products reflect the amount of iodine used in the animal feed). On the other hand, seaweed is always a good source as it absorbs iodine from seawater. Kombu (kelp) is exceptionally rich in iodine – the highest amount of iodine in any food, so whilst seaweed consumption is encouraged, use kelp very sparingly.

Excess iodine can disrupt thyroid function leading to weight gain, hypothyroidism or hyperthyroidism. The Department of Health advise that intakes of up to 500 micrograms a day of iodine are unlikely to cause harm.

Do I need a supplement?

No, a healthy vegan diet containing the above foods on a daily basis, with some occasional seaweed and/or iodised salt (used sparingly) will cover your needs. 

The best plant sources

The best plant sources of iodine include sea vegetables (kombu, arame, wakame and nori) and iodised salt. The following foods have varying iodine content depending on iodine levels in the soil in which they’re grown: wholegrains, green beans, courgettes, kale, spring greens, watercress, strawberries and organic potatoes with skin. Amounts tend to be low and variable.

Signs of deficiency

enlarged thyroid gland (goitre), tiredness, weight-gain, increased susceptibility to infections, depression, feeling cold at all times and dry and cracked skin.