Iodine helps make the thyroid hormones, which keep cells and the metabolic rate healthy. As with vitamin D, there is concern that many UK citizens, vegan or not, are not receiving adequate iodine in their diet.
- Some countries add iodine to table salt (but we realise salt is not exactly a health food!). A better, regular source of iodine can be obtained from sea vegetables or supplements.If you regularly eat seaweed (multiple times a week), you will probably get adequate iodine from the seaweed. However, the availability of iodine from seaweed is variable and it can provide too much iodine.**
- Health professionals suggest a modest iodine supplement: 75-150 µg every few days.
- Cereals and grains can also be good source of iodine, but this depends on the amount of iodine in the soil where these foods are grown. 
**Word of caution: you can consume too much iodine by eating kelp, and hijiki should be avoided as it has been found to be contaminated with arsenic.
 Rose, M, Lewis J, Langford N, et al. Arsenic in seaweed forms, concentration and dietary exposure. Food Chem Toxicol. 2007;45(7):1263-7