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"Some seaweeds, most notably
the kelps, may have very high levels of iodine."
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Not all algae are equally
beneficial. Microcystin toxins are a health hazard, and have been detected
in some blue-green algae supplements. (21) In our study, we used spirulina
(Earthrise Nutritionals), grown under carefully maintained culture tanks
and known to be free of Microcystin. Some seaweeds, most notably the kelps,
may have very high levels of iodine. (22) In a previous study, we determined
that wakame (Undaria) had the lowest iodine content of the commercially
available edible brown seaweeds. Our seaweed, Undaria pinnatifida, was
from Tasmania (provided by Marinova), and had been tested for iodine content
(22 - 53 µg/g). Thus our dose of 5 grams of seaweed provided 110
- 265 µg of additional iodine. |
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The Lowest-Observed-Adverse-Effect
Level (LOAEL), based on increases in serum Thyroid Stimulating Hormone
(TSH), is 1,700 µg/day (U.S. and Canadian RDI Committee). (23) When
seaweed is eaten as food, the normal preparation and cooking methods greatly
reduce iodine and differences among seaweeds become much less important.
For people who are allergic to iodine (seafood or shellfish allergies),
seaweed should be avoided. The kind of seaweed in a capsule would be important,
as all the iodine present would be released in the stomach. It is therefore
best to only use wakame (Undaria) supplements, but any of the common edible
brown seaweeds would be safe if cooked.
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