Grace Forsythe, Health Campaigner at Viva! Health, explores vegan sources of iodine, and why it’s such an important mineral
What is iodine?
Iodine is an essential element which is used by the body to make the thyroid hormones triiodothyronine (T3) and thyroxine (T4). These hormones control the speed at which almost all cells in your body work, which in turn controls the production of proteins, bone growth, development of the central nervous system and so many more vital processes!
How much do we need?
The UK government recommend 140 micrograms (μg) per day but doesn’t mention pregnant or breastfeeding women specifically. However, the European Food Safety Authority recommends 200 μg per day for them. Many foods contain iodine including wholegrains, green beans, courgettes, kale, spring greens, watercress, strawberries and organic potatoes with skin. However, amounts tend to be low and variable so you may need to ensure you are getting enough.
The thyroid gland can store around 10-20 milligrams (a milligram is one-thousand times more than a microgram) so as long as you have a good regular source of iodine it’s okay to have some iodine-free days.
Symptoms of deficiency
Long-term deficiency of iodine can lead to swelling of the thyroid gland in the throat, which is known as a goitre. Symptoms may include a cough, tight feeling in the throat, changes to your voice or difficulty swallowing or breathing. When the body can’t produce enough thyroid hormones you may experience fatigue, depression, forgetfulness, slow thoughts, weight gain, dry skin and feel the cold more than usual.
Vegan sources of iodine
Most of the Earth’s iodine is found in the ocean and as a result, seaweed is packed full of it. Kelps such as kombu should be avoided as they generally contain too much iodine. Just one gram of kombu can be more than 2,000 per cent higher than the daily recommended amount! The iodine content of nori is much safer, with one dried snack pack containing around 50-80 per cent of the recommended amount. You can also crumble nori up and add it to noodles, stews, soups or pasta dishes. (Check out our recipe for Quinoa Maki Rolls for a tasty way to include nori in your day.)
Unlike many other countries, the UK doesn’t iodise table salt and many experts are currently calling for this to be reviewed. Cerebos is one brand of table salt available in some UK supermarkets, with a 1.5 gram serving (¼ teaspoon) providing around 30 μg, or 21 per cent of the recommended amount. Try to limit your daily salt intake to less than six grams (one teaspoon) per day.
There are now plant milks available that are fortified with iodine in the form of potassium iodide, including: Alpro Soya Original (that’s the chilled version but fortification is planned for the UHT version), Qwerkee Pea M’lk, Koko Super (enriched with eight vitamins and minerals) and Marks and Spencer’s own brand soya, oat and rice milks. A 250ml glass of these can provide around 60-70 μg of iodine – around 50 per cent of the recommended amount. If you don’t have other vegan sources of iodine, try switching to one of these drinks.
Many multivitamins don’t contain iodine so if you don’t have any seaweed or fortified milk in your diet, switch to one that does contain it. Kelp supplements should be avoided as the iodine content can vary greatly from what is claimed on the label. Iodine has a very high absorption rate so supplements containing more than 140 μg aren’t necessary and could be harmful. Iodine can interfere with the function of some medications, so it’s best to talk to your doctor before taking supplements, especially if you have an existing thyroid condition.
Some people get their iodine from dairy, sea fish and shellfish. But bear in mind that most fish are contaminated with polychlorinated biphenyls, dioxins and mercury and these increase the risk of cancer and endocrine disruption. This is a particular problem with fish that the government encourages people to eat, such as salmon. Raw fish can also contain harmful parasites, viruses and bacteria. Iodine is not a natural component of cow’s milk and comes from supplemented cattle feed and iodine-containing disinfectant teat washes.
Iodine deficiency during pregnancy carries serious risks for both mother and baby. During the first 14-16 weeks of pregnancy, the foetus is entirely dependent on the mother’s thyroid hormones until he or she can produce their own, which is why pregnant women require additional iodine. Sufficient iodine levels are important during pre-conception and breastfeeding also to ensure healthy brain formation in the foetus and thyroid hormone production in the infant. Women who enter pregnancy with adequate stores of iodine are at least partially protected but it’s important to maintain iodine intake throughout pregnancy in case stores run low. Iodine deficiency is the most common cause of mental impairment in children and can cause congenital iodine deficiency syndrome, previously known as cretinism.
Recent studies looking at the iodine status of pregnant women in the UK suggest that many are mildly-to-moderately deficient and that these women were more likely to give birth to children with lower IQ.
The importance of iodine is generally not well known and certain groups, including pregnant women, may be at risk of deficiency. There are reliable vegan sources of iodine, and you can help spread the word by ensuring that your friends and family have a good source in their diets.
• Viva! Health is part of the charity Viva!, Europe’s largest vegan campaign group. We monitor scientific research linking diet to health and provide accurate information on which you can make informed choices about the food you eat – vivahealth.org.uk