· By GUUDIES Editorial Team
Sea Moss and Iodine: How Much Is Safe? A UK Guide Using NHS Limits
By the GUUDIES Editorial Team · Published 26 October 2026 · Sources listed at the end.
Disclosure: GUUDIES sells a daily pouch that includes a sea moss gummy and a multivitamin gummy containing iodine. This guide is about safety, so we include our own numbers.
The short answer: adults in the UK need 140 micrograms (µg) of iodine a day. The NHS says taking 500µg or less a day from supplements is unlikely to cause harm. The risk with sea moss is not that it contains iodine but that you often cannot tell how much: seaweed iodine varies hugely between species and batches, and kelp can contain far more than you need in a small amount.
Iodine numbers at a glance
| Measure | Amount per day | Source |
|---|---|---|
| What adults need (UK) | 140µg | NHS |
| Nutrient reference value used on labels | 150µg | GB food labelling rules |
| Supplement amount unlikely to cause harm | 500µg or less | NHS |
| Tolerable upper intake level (all sources) | 600µg | European Food Safety Authority |
Why iodine matters
Iodine contributes to the normal production of thyroid hormones and normal thyroid function, and to normal cognitive function and energy-yielding metabolism. These are authorised health claims for iodine in Great Britain. In the UK, most people get iodine from milk, dairy, white fish and eggs. People who eat little of these, including many vegans, may get less than they need.
Why sea moss is hard to dose
Seaweeds absorb iodine from seawater, but the amount depends on the species, where and when it was harvested, and how it was dried and prepared. A study of commercially available seaweeds found iodine levels varied many times over between products, with brown kelps far higher than red seaweeds such as Irish moss (Teas et al., 2004). Soaking and boiling can also remove some of it.
That means a spoonful of home-made sea moss gel could provide very little iodine or quite a lot, and you would not know which. Kelp is the bigger concern: a small amount of some kelp products can exceed the upper limit.
What happens if you have too much iodine?
The NHS says taking high doses of iodine for a long time could change the way your thyroid gland works, which can cause symptoms such as weight gain. Too much and too little iodine can both affect the thyroid. Signs of a thyroid problem should always be checked by a GP rather than treated with supplements.
Who should check with a GP before taking sea moss?
- Anyone with a diagnosed thyroid condition, or taking levothyroxine or other thyroid medicine
- People who are pregnant, trying to conceive or breastfeeding
- Anyone already taking kelp, another seaweed or a high-iodine supplement
- Anyone taking regular prescription medication
How to keep your total iodine sensible
- Add up the iodine stated on every supplement you take each day.
- Prefer products that state iodine per serving over raw gel or unlabelled powders.
- Do not combine kelp with other seaweed supplements unless your GP agrees.
- Look for brands that test each batch for heavy metals, as seaweed can also take up arsenic and other metals. The Food Standards Agency advises against eating hijiki seaweed for this reason.
How much iodine is in a GUUDIES pouch?
The Daily Greens+ gummy provides 38µg of iodine as potassium iodide. The Sea Moss gummy contains 40mg of Irish sea moss extract (50:1, equivalent to 2,000mg of raw seaweed); we do not currently state a separate iodine amount for it. If you take other iodine-containing supplements, include the 38µg in your total, and speak to your GP if you have a thyroid condition.
Common questions
How much iodine do I need a day?
The NHS says adults need 140µg a day, and most people can get this from a varied diet.
How much iodine is too much?
The NHS says 500µg or less a day from supplements is unlikely to cause harm. The European Food Safety Authority sets the upper limit from all sources at 600µg a day for adults.
Does sea moss gel contain a lot of iodine?
It can, but the amount varies widely between batches and species, so you usually cannot tell how much you are getting.
Can I take sea moss with a thyroid condition?
Speak to your GP first, particularly if you take thyroid medication.
Is sea moss safe in pregnancy?
Iodine needs change in pregnancy and both too little and too much matter, so check with your midwife or GP before taking any seaweed supplement.
Sources
- NHS. Iodine. nhs.uk
- European Food Safety Authority. Tolerable upper intake levels for vitamins and minerals. efsa.europa.eu
- Teas J et al. Variability of iodine content in common commercially available edible seaweeds. Thyroid 2004. PubMed
- Food Standards Agency. food.gov.uk
- Great Britain nutrition and health claims register. gov.uk