Iodine and seaweeds

Iodine is a metalloid, belonging to the group of halogens with Chloride, Fluor... It is considered as a micro-nutrient for humans.

Iodine is a component of seaweeds. 

https://www.healthline.com/nutrition/iodine-rich-foods 

Iodine can help people with iodine deficiency but could be deleterious in excess. https://www.ncbi.nlm.nih.gov/books/NBK501850/




"This is the reason why in 2002, EFSA's Scientific Committee on Food (SCF) suggested a tolerable upper intake level (UL) for adults of 600 μg iodine/day and adjusted this for the remaining age groups based on differences on body surface area (body weight0.75) (European Commission, 2002). "

Table 1

Average (±SD) and range levels (μg/g fdw) of iodine, total arsenic, mercury, lead and cadmium

	No. samples	Iodine		Total arsenica		Mercury		Lead		Cadmium
		Average (± SD)	Range (min–max)	Average (± SD)	Range (min–max)	Average (± SD)	Range (min–max)	Average (± SD)	Range (min–max)	Average (± SD)	Range (min–max)
Phaeophyta (brown algae)
Saccharina latissima	16	2,302.5 (1,098.18)	333.0–4,782.2	38.324 (8.713)	22.504–54.117	0.016 (0.005)	0.007–0.023	0.257 (0.222)	0.072–0.708	0.682 (0.216)	0.231–0.966
Fucus vesiculosus	27	274.9 (75.87)	137.8–451.2	28.379 (19.690)	10.358–116.677	0.012 (0.007)	0.003–0.042	0.897 (1.730)	0.189–9.601	0.780 (0.372)	0.299–1.969
Fucus spiralis	1	209.52	–	8.940	–	0.019	–	0.956	–	0.464	–
Fucus evanescens	1	394.16	–	14.084	–	0.008	–	0.506	–	0.520	–
Fucus serratus	14	366.46 (197.92)	105.2–961.4	30.269 (9.579)	21.457–56.277	0.009 (0.003)	0.005–0.015	0.465 (0.177)	0.236–0.865	1.044 (0.339)	0.628–1.561
Chlorophyta (green algae)
Ulva lactuca	2	18.97 (2.52)	17.2–20.8	3.399 (0.293)	3.192–3.606	0.007 (0.002)	0.005–0.008	0.078 (0.019)	0.064–0.092	0.038 (0.030)	0.0168–0.059
Cladophora sp.	1	140.27	–	7.069	–	0.007	–	1.447	–	0.782	–

SD: standard deviation.

aData on inorganic arsenic is in preparation.

Table 2

Estimated average and 95th percentile exposure to iodine (μg/day), mercury, lead and cadmium (μg/kg bw per day) due to the consumption of a single serving size of 5 g fdw of seaweed, considering each species individually and altogether. For species with only one representative sample, the total content was considered for exposure calculation

	Iodine (μg/day)		Mercury (μg/kg bw per day)		Lead (μg/kg bw per day)		Cadmium (μg/kg bw per day)
	Average	95th percentile	Average	95th percentile	Average	95th percentile	Average	95th percentile
Species‐specific exposure
Fucus vesiculosus	1,374.6	274.9	0.00100	0.0015	0.0747	0.14424	0.0650	0.0928
Fucus serratus	1,832.2	2,523.2	0.00099	0.0010	0.0387	0.05998	0.0870	0.1217
Fucus spiralis	1,047.6	–	0.00161	–	0.0796	–	0.0387	–
Fucus evanescens	1,970.8	–	0.00069	–	0.0421	–	0.0433	–
Saccharina latissima	11,512.3	18,677.2	0.00135	0.0018	0.0214	0.05380	0.0568	0.0772
Ulva lactuca	94.9	86.0	0.00055	0.0004	0.0065	0.00536	0.0031	0.0014
Cladophora sp.	701.3	–	0.00062	–	0.1205	–	0.0652	–
Population of samples
	4,052.7	13,631.1	0.0010	0.0016	0.0521	0.0786	0.0652	0.1194

bw: body weight.

"On the other hand, intake of iodine due to a single serving of seaweed might easily exceed the UL for iodine (600 μg/day for adults and 200 μg/day for children), as observed for all of the species of brown algae and particularly for Saccharina latissima (average > 11,000 μg/day and 95th percentile > 18,000 μg/day). In general, consumption of brown seaweeds rich in iodine, namely Saccharina latissima, once a week would not represent a problem for the general healthy population. However, when considering at high risk subgroups: pregnant women (due to the importance of thyroid hormones in fetal development), children and individuals with thyroid dysfunction, a more careful evaluation regarding the species, amount and frequency of seaweed consumed should be done. Species with lower iodine content should be selected and iodine‐rich species should be avoided due to lack of knowledge on the long‐term exposure effects in fetus and children."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015483/

"3.3.3. Iodine

A 7700 inductively coupled plasma mass spectrometer (ICP-MS) from Agilent Technologies, equipped with nickel sampler and skimmer cones and a collision/reaction cell, was used for iodine determination. Rh was used as the internal standard. TMAH extracts were conveniently diluted before ICP-MS measurement and the dilution was varied from 1:5 to 1:20. Isotope of 127I was analyzed, with 3.0 mL/min of He as the reaction gas to avoid interferences on this mass. The limit of detection (LOD) and the limit of quantification (LOQ) of the ICP-MS measurements were 0.5 and 1.3 μg/L, respectively, for I. The accuracy of our method was validated by Seronorm TM trace elements Blood L2 standard reference material. The CRM determination value for I was 86.6 ± 5.8 ng/g, while the reference value on the certificate was 107 ± 22 ng/g."

https://www.mdpi.com/1420-3049/24/18/3408/htm