Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency

[helvella]

A rather complicated picture emerges from supplementing with 60 micrograms of selenium a day. At least in pregnancy.

Eur J Nutr. 2014 Dec 19. [Epub ahead of print]

Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency.

Mao J1, Pop VJ, Bath SC, Vader HL, Redman CW, Rayman MP.

Author information

1Department of Nutritional Sciences, Faculty of Health and Medical Sciences, University of Surrey, Guildford, GU2 7XH, UK.

Abstract

PURPOSE:

Selenium is an essential trace mineral and a component of selenoproteins that are involved in the production of thyroid hormones and in regulating the immune response. We aimed to explore the effect of low-dose selenium supplementation on thyroid peroxidase antibody (TPO-Ab) concentration and thyroid function in pregnant women from a mild-to-moderate iodine-deficient population.

METHODS:

Samples and data were from a secondary analysis of Selenium in PRegnancy INTervention (SPRINT), a double-blind, randomized, placebo-controlled study that recruited 230 women with singleton pregnancies from a UK antenatal clinic at 12 weeks of gestation. Women were randomized to receive 60 µg/day selenium or placebo until delivery. Serum thyroid peroxidase antibodies (TPO-Ab), thyrotropin (TSH) and free thyroxine (FT4) were measured at 12, 20 and 35 weeks and thyroglobulin antibodies (Tg-Ab) at 12 weeks.

RESULTS:

93.5 % of participants completed the study. Se supplementation had no more effect than placebo in decreasing TPO-Ab concentration or the prevalence of TPO-Ab positivity during the course of pregnancy. In women who were either TPO-Ab or Tg-Ab negative at baseline (Thy-Ab-ve), TSH increased and FT4 decreased significantly throughout gestation (P < 0.001), with no difference between treatment groups. In women who were Thy-Ab+ve at baseline, TSH tended to decrease and was lower than placebo at 35 weeks (P = 0.050). FT4 fell more on Se than placebo supplementation and was significantly lower at 35 weeks (P = 0.029).

CONCLUSIONS:

Low-dose selenium supplementation in pregnant women with mild-to-moderate deficiency had no effect on TPO-Ab concentration, but tended to change thyroid function in Thy-Ab+ve women.

PMID:

25524327

[PubMed - as supplied by publisher]

ncbi.nlm.nih.gov/pubmed/255...

Rod

[PR4NOW]

Rod, it would be nice to see them check levels for pre-conception planning and supplement accordingly. PR

[Clutter]

I thought selenium was supposed to improve thyroid function? It appears to make it worse in the positive antibody group.

[helvella Administrator Thyroid UK in reply to Clutter]

I think there has been too much assumption around selenium.

I have long been unhappy at recommendations that people take 400 micrograms (sometimes even more), long term.

Certainly, if we have not got enough selenium to make the various selenoproteins, we have a problem. But we really don't need very much.

[Spareribs]

if iodine deficient... it all works together - no matter how many brazil nuts at Xmas!

whereas Vit D would definately help....

nhs.uk/start4life/Pages/vit...

[davidhammond]

Perhaps those who were supplemented with selenium were then able to more efficiently convert FT4 to FT3, ( as selenium is required for one of the deiodinase enzymes) resulting in lower levels of FT4. Unfortunately researchers did not measure the levels of FT3.

[helvella Administrator Thyroid UK in reply to davidhammond]

That is certainly one reason I am sceptical that simply supplementing selenium is appropriate. Certainly we need adequate levels.

There is also onward conversion of T3 (and rT3) to T2...

[Hidden]

I have been on a high dose of selenium since i started managing my own health. My antibodies are down by over two thirds as a result

[helvella Administrator Thyroid UK in reply to Hidden]

How do you know that it was due to the selenium?