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Iodide, antioxidant function and omega-6 and omega-3 fatty acids: a new hypothesis of a biochemical cooperation?
Iodide, antioxidant function and omega-6 and omega-3 fatty acids:
a new hypothesis of a biochemical cooperation?
Cocchi M. and Venturi S.
Progress in Nutrition. 2000;2, 1:15-19

Introduction.

There is evidence in the most recent scientific literature (1,2,3) that iodide plays two different roles:

1. antioxidant
2. hormonal

Both biological functions seem to coexist in the superior animal cells.

Iodide is, also, strictly connected with two of the most important polyunsaturated fatty acids, Arachidonic Acid (AA, omega-6) and Docosahexaenoic Acid (DHA, omega-3), to forms specific iodolipids. Iodide, AA and DHA are determinant factors in brain development (4,5,6), having common metabolic pathways to guarantee brain growth and function. Those substances find a common denominator in the biochemical process which protect brain and nervous cells from peroxidative damage (7,8).

In order to explain the biochemical hypothesis we must consider the phylogenetic and embryogenetic role of iodide and the modern explanation of AA and DHA during brain development and chemical maturation (9,10,11). Iodine is the richest in electrons among the element required in the diet. In nature, iodine exists as iodide ions (I-) and in this form is taken into the cells. Inorganic iodides are necessary for all living vegetal and animal cells, but only the Vertebrates have thyroid gland and its iodinated hormones.

In humans, total amount of iodine is about 30.000 -50.000 mcg, and less than 20% are present in thyroid hormones and gland. About 60-80% og total iodine is non-hormonal and it is contentrated in non-thyroid tissues. The biological role of non-thyroid inorganic iodine is still unknown. Recently it has been hypothesized (2,12,13) that iodide might have, phylogenetically and evolutionistically, an ancient antioxidant role in all iodide-concentrating cells. Into these cells iodide acts as an electron donor in the presence of H2O2 and peroxidase (14). The remaining iodine readily iodinates the tyrosine and (more slowly) the histidine or some specific lipid, and so, neutralizes its owv high oxidant power.

In fact, three billion years ago, Algae, which contain a high amount of iodine, were the first living cells to produce oxygen (which was toxic at that time) in terrestrial atmosphere. So, algal cells required a protective antioxidant action in which iodides might have had a specific role. Our hypothesis has now been confirmed experimentally in Algae by a recent study carried uot by Kupper et al. (15), and we....

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