Lab-tested kelp iodine supplements in the UK and EU: heavy metals and iodine dose (2026)

Q: Which kelp supplement has the lowest heavy metals?

Among the lab-verified kelp capsules we list, VitaMoment Jod (aus Kelp) has the lowest measured lead (0.074 mg/kg), cadmium (0.12 mg/kg) and mercury (<0.010 mg/kg) (GBA report, batch L70014B, Nov 2025). naturalie Natur Jod has the lowest inorganic arsenic (0.090 mg/kg) but the highest total arsenic (36 mg/kg), mostly in organic forms. All values are well under the EU 2023/915 supplement limits: lead 3.0, cadmium 1.0 (3.0 for supplements of at least 80% dried seaweed) and mercury 0.10 mg/kg.

Q: What is the best iodine supplement in the UK?

We only rate seaweed (kelp) iodine supplements, not potassium iodide tablets, and the lab report decides the order, not the brand. None of the three lab-verified kelp capsules has a UK seller in our data. The only kelp iodine product with a UK seller we list is Sunday Natural Organic Iodine 250 (£12.90 for 120 capsules, about £0.11 a day, checked 26 Oct 2026). Its GBA certificate (Oct 2026) says the batch passed but gives no values, so we label it “Partial report”. It declares 250 µg a day, above BfR’s 100 µg advice. We have not checked whether the German shops deliver to the UK.

Q: How much iodine should a kelp supplement contain?

The EU reference intake (NRV) is 150 µg a day. Germany’s BfR recommends no more than 100 µg per daily supplement dose (150 µg in pregnancy and breastfeeding), and the EU adult upper limit is 600 µg a day from all sources. In our list, edubily declares 100 µg, VitaMoment and natural elements 150 µg, naturalie 200 µg and Sunday Natural 250 µg per capsule. Only one report measured iodine: VitaMoment, 218 µg per capsule against 150 µg declared. Not medical advice: if you have a thyroid condition, are pregnant or take thyroid medicine, ask a doctor or pharmacist first.

Q: Does kelp contain arsenic?

Yes. Seaweed usually has a lot of total arsenic, mostly in organic forms. Inorganic arsenic is the more toxic form, and there is no EU limit for arsenic in supplements. Measured inorganic arsenic in our lab-verified kelp capsules: naturalie 0.090, VitaMoment 0.44 and edubily 0.84 mg/kg.

Q: Are spirulina and chlorella the same as kelp?

No. Spirulina and chlorella are microalgae, not kelp, and they are not sold as iodine sources. We compare their lead, cadmium, mercury and arsenic results separately on the spirulina and chlorella (greens) page.

Short answer:

Three kelp iodine capsules in our directory are lab verified, with measured heavy-metal results for a named batch from GBA, an accredited German lab: VitaMoment Jod (lead 0.
074, cadmium 0.
12 mg/kg, Nov 2025), naturalie Natur Jod (lead 0.
11, cadmium 0.
29 mg/kg, Jul 2025) and edubily Iod Kapseln (lead 0.
14, cadmium 0.
79 mg/kg, Aug 2026).
All three are within the EU 2023/915 supplement limits and all three are sold only by German shops.
Lowest lead, cadmium and mercury: VitaMoment.
Lowest declared iodine: edubily at 100 µg a capsule, the only one within BfR’s 100 µg advice.
VitaMoment’s report measured 218 µg of iodine per capsule against 150 µg declared.
For UK buyers, the only kelp iodine product with a UK seller in our data is Sunday Natural Organic Iodine 250 (sunday-natural.
co.
uk): its certificate gives pass/fail without values (“Partial report”) and it declares 250 µg a day.

Guide: iodine and heavy metals in seaweed, kelp and sea moss supplements →

Lab-tested sea moss in the UK: the honest answer (one partial report so far) →

Data from published lab reports only; updated 2026-11-01. Not medical advice. Testing status can’t be bought.

Full seaweed comparison: sortable table of every product →

Lab results

Product	Seller	Lab-test status	Pb	Cd	Hg	As	Price	Red flags
VitaMoment Jod (aus Kelp) iodine from kelp, 120 capsules	VitaMoment (vitamoment.de, DE) · EU	Lab verified3 Nov 2025Report	0.074 (well under the EU limit or below detection)	0.12 (well under the EU limit or below detection)	<0.010 (well under the EU limit or below detection)	7.6 (no EU limit)	€19.97 / 120 capsules ≈ €0.17 per day at 1 capsule (calculated, checked 26 Oct 2026). EU seller (Germany); no UK seller found.	⚠ 3 red flags Iodine measured at 218 µg per capsule, 45% above the 150 µg on the label and more than twice the 100 µg per daily dose Germany’s BfR recommends for supplements. Total arsenic 7.6 mg/kg (inorganic arsenic, the more toxic form, 0.44 mg/kg). The sample was sent in by the brand: check the batch number on your pack.
edubily Iod Kapseln (organic kelp iodine) 180 capsules	edubily (edubily.de, DE) · EU	Lab verified12 Aug 2026Report	0.14 (well under the EU limit or below detection)	0.79 (near the EU limit)	0.021 (well under the EU limit or below detection)	NT (not tested)	€19.95 / 180 capsules ≈ €0.11 per day at 1 capsule (calculated, checked 26 Oct 2026). EU seller (Germany); no UK seller found.	⚠ 3 red flags Cadmium 0.79 mg/kg, the highest in this list: 79% of the 1.0 mg/kg limit the lab applied. No total arsenic result (inorganic arsenic 0.84 mg/kg, the highest inorganic value in this list), and iodine was not measured for this batch. The sample was sent in by the brand: check the batch number on your pack.
naturalie Natur Jod Kapseln (organic kelp iodine) 180 capsules	naturalie (naturalie.de, DE) · EU	Lab verified31 Jul 2025Report	0.11 (well under the EU limit or below detection)	0.29 (well under the EU limit or below detection)	0.014 (well under the EU limit or below detection)	36 (no EU limit)	€22.99 / 180 capsules ≈ €0.13 per day at 1 capsule (calculated, checked 26 Oct 2026). EU seller (Germany); no UK seller found.	⚠ 4 red flags Iodine per capsule is above the 100 µg per daily dose that Germany’s BfR recommends as the maximum for supplements (150 µg in pregnancy and breastfeeding); ask a doctor or pharmacist first if you have a thyroid condition. Total arsenic 36 mg/kg, the highest in this list (inorganic arsenic only 0.090 mg/kg). Report dated 31 Jul 2025 (about 15 months old) and iodine was not measured. The sample was sent in by the brand: check the batch number on your pack.
Sunday Natural Organic Iodine 250 µg from kelp, 120 capsules	Sunday Natural (sunday-natural.es, EU) · EU + Sunday Natural (sunday-natural.co.uk) · UK	Partial reportReport	Pass* (certificate states compliance, no figure)	Pass* (certificate states compliance, no figure)	Pass* (certificate states compliance, no figure)	Tested† (tested, but the certificate gives no figure or verdict)	€12.90 / 120 capsules ≈ €0.11 per day at 1 capsule on sunday-natural.es; £12.90 / 120 capsules ≈ £0.11 per day on sunday-natural.co.uk (calculated, checked 26 Oct 2026). € and £ prices are separate sellers, not converted.	⚠ 3 red flags Pass/fail certificate only: it states compliance with EU limits but gives no measured values, so we list it as a partial report. Iodine per capsule is above the 100 µg per daily dose that Germany’s BfR recommends as the maximum for supplements (150 µg in pregnancy and breastfeeding); ask a doctor or pharmacist first if you have a thyroid condition. The sample was sent in by the brand: check the batch number on your pack.
natural elements Jod aus Bio-Kelp (organic kelp iodine) 365 capsules	natural elements (naturalelements.de, DE) · EU	Partial reportReport	Pass* (certificate states compliance, no figure)	Pass* (certificate states compliance, no figure)	Pass* (certificate states compliance, no figure)	Pass* (certificate states compliance, no figure)	€23.99 / 365 capsules ≈ €0.066 per day at 1 capsule (calculated, checked 26 Oct 2026). EU seller (Germany); no UK seller found.	⚠ 3 red flags Pass/fail certificate only: it states compliance with EU limits but gives no measured values, so we list it as a partial report. Contains maltodextrin as a filler and sulphites. The sample was sent in by the brand: check the batch number on your pack.
Mighton’s Plain Sea Moss Gel (St Lucian gold sea moss) 300 ml	Mighton’s Organic (mightons.co.uk, UK) · UK	Partial reportReport	0.07 (well under the EU limit or below detection)	0.72 (near the EU limit)	0.01 (well under the EU limit or below detection)	5.78 (no EU limit)	£9.99 / 300 ml (500 ml £14.99), plus £4.99 chilled postage (seen 26 Oct 2026). No daily serving is stated, so we can’t calculate a daily cost. UK seller; no EU seller found.	⚠ 3 red flags No batch number on the certificate, and all four metal tests are marked as subcontracted outside the lab’s UKAS accreditation (the brand’s page describes the testing as accredited). Cadmium 0.72 mg/kg and total arsenic 5.78 mg/kg; arsenic was not split into inorganic and organic forms, so the brand’s statement that it is mostly harmless organic arsenic is not shown by this report. No iodine result and no daily serving on the label page.

Heavy-metal colours: Well under the EU limit (below half) or below detection Near the EU limit (half the limit up to the limit) Over the EU limit Grey: no EU limit (arsenic), not tested, or the lab’s reporting limit is above the EU limitEU 2023/915 limits for food supplements: lead (Pb) 3.0, cadmium (Cd) 1.0, mercury (Hg) 0.10 mg/kg. Values in mg/kg. NT = not tested; c = calculated by us from µg per serving.

EU 2023/915 limits for food supplements: lead 3.0, cadmium 1.0, mercury 0.10 mg/kg. “Pass (no value)” means the certificate states compliance without a measured figure. “—” means no readable report on file.

About Seaweed

What it is: Brown seaweeds such as kelp (Laminaria species) and knotted wrack (Ascophyllum nodosum, often sold as “Norwegian kelp”), dried and sold in capsules mainly as a natural source of iodine; and sea moss (Irish moss or gold sea moss, red seaweeds), usually sold as a gel.
Common forms: Capsules of dried seaweed powder standardised to an iodine dose, or fresh sea moss gel in a refrigerated jar.
Typical label doses: Kelp capsules in our directory declare 100–250 µg iodine per daily capsule. The sea moss gel we list states no daily serving.
Note: Seaweed concentrates iodine and can take up cadmium, lead and arsenic from seawater. Iodine varies hugely between seaweeds and batches, so a measured iodine value matters as much as the metals. Germany’s BfR recommends no more than 100 µg iodine per daily dose in supplements (150 µg in pregnancy and breastfeeding). If you have a thyroid condition, are pregnant or take thyroid medicine, ask a doctor or pharmacist before taking iodine supplements.

Seaweed and sea moss have no authorised EU or GB health claims of their own. Iodine has authorised claims, but they only apply to products that provide at least 15% of the iodine reference intake per daily portion, so we don’t repeat them on these comparison pages and we make no benefit claims for sea moss.

Information only, not medical advice. Food supplements are not intended to diagnose, treat, cure or prevent any disease. Speak to a healthcare professional before use, especially if pregnant or on medication.

FAQ

Which kelp supplement has the lowest heavy metals?

Among the lab-verified kelp capsules we list, VitaMoment Jod (aus Kelp) has the lowest measured lead (0.074 mg/kg), cadmium (0.12 mg/kg) and mercury (<0.010 mg/kg) (GBA report, batch L70014B, Nov 2025). naturalie Natur Jod has the lowest inorganic arsenic (0.090 mg/kg) but the highest total arsenic (36 mg/kg), mostly in organic forms. All values are well under the EU 2023/915 supplement limits: lead 3.0, cadmium 1.0 (3.0 for supplements of at least 80% dried seaweed) and mercury 0.10 mg/kg.

What is the best iodine supplement in the UK?

We only rate seaweed (kelp) iodine supplements, not potassium iodide tablets, and the lab report decides the order, not the brand. None of the three lab-verified kelp capsules has a UK seller in our data. The only kelp iodine product with a UK seller we list is Sunday Natural Organic Iodine 250 (£12.90 for 120 capsules, about £0.11 a day, checked 26 Oct 2026). Its GBA certificate (Oct 2026) says the batch passed but gives no values, so we label it “Partial report”. It declares 250 µg a day, above BfR’s 100 µg advice. We have not checked whether the German shops deliver to the UK.

How much iodine should a kelp supplement contain?

The EU reference intake (NRV) is 150 µg a day. Germany’s BfR recommends no more than 100 µg per daily supplement dose (150 µg in pregnancy and breastfeeding), and the EU adult upper limit is 600 µg a day from all sources. In our list, edubily declares 100 µg, VitaMoment and natural elements 150 µg, naturalie 200 µg and Sunday Natural 250 µg per capsule. Only one report measured iodine: VitaMoment, 218 µg per capsule against 150 µg declared. Not medical advice: if you have a thyroid condition, are pregnant or take thyroid medicine, ask a doctor or pharmacist first.

Does kelp contain arsenic?

Yes. Seaweed usually has a lot of total arsenic, mostly in organic forms. Inorganic arsenic is the more toxic form, and there is no EU limit for arsenic in supplements. Measured inorganic arsenic in our lab-verified kelp capsules: naturalie 0.090, VitaMoment 0.44 and edubily 0.84 mg/kg.

Are spirulina and chlorella the same as kelp?

No. Spirulina and chlorella are microalgae, not kelp, and they are not sold as iodine sources. We compare their lead, cadmium, mercury and arsenic results separately on the spirulina and chlorella (greens) page.

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