In this project, the investigators propose an intervention design testing the efficacy of a food reformulated with seaweed as an ingredient in meal, capsules against placebo and no intervention controls. The randomised control trial (supplementation) will last 24 weeks. The aim is to study the effect of the food matrix on variables associated with iodine nutrition: iodine status and thyroid function.
This study is a randomized, double-blind, placebo-controlled trial conducted in Glasgow, United Kingdom. Inclusion criteria are as follows: healthy premenopausal women aged 18 - 60 years who would remain a resident in Glasgow for 24 weeks; who were self-reported low iodine consumers consuming milk less than once per day and non-oily fish less than once per week. Those with a history of thyroid dysfunction, taking medications other than the contraceptive pill or smoking, as well as pregnant or lactating women and those planning to conceive, were excluded. Those taking dietary supplements containing iodine would also excluded and there was no restriction related to body mass index (BMI). Participants are recruited via social media and advertisements displayed around the Greater Glasgow area. Interested parties are screened and, if eligible, invited to a 30-minute appointment at which participants were randomly assigned through a web-based randomisation service to one of four groups after consent is obtained; reformulated pizza, control pizza, iodine capsules, or placebo capsules. During this initial meeting anthropometric measurements, blood pressure and a venous blood sample are collected, and participants are also asked to complete a sociodemographic questionnaire and an iodine specific food frequency questionnaire (FFQ). Participants are provided with instructions and equipment to record a 3-day estimated food diary and to collect 12 spot urine samples at different times of day over 2-7 days. Upon returning the spot urine samples, participants were given either the pizzas or supplements to begin the intervention. Participants are asked to consume one pizza or supplement three times a week for 24 weeks. Participants are asked to collect a further 10-12 sample spot urine samples at week 2 of the intervention. Participants are asked to attend another 30-minute appointment at 12 and 24 weeks in which baseline measurements are repeated along with a change to diet questionnaire.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
96
Reformulated food with 400ug of iodine per meal, three times per week (to achieve 122% of weekly recommended intakes - average 140ug/day).
Control (placebo) meal to consume thrice weekly (no iodine supplementation).
Capsules containing seaweed extract, the iodine-rich ingredient in the reformulated pizza, 400ug iodine per capsule, to be consumed three times per week (122% of weekly recommended intake).
University of Glasgow
Glasgow, United Kingdom
Change in urinary iodine concentration (UIC)
Change in UIC assessed in pooled spot urine samples at 12 weeks, from baseline
Time frame: 0, 12 weeks
Change in urinary iodine concentration (UIC)
Change in UIC assessed in pooled spot urine samples at 24 weeks, from baseline
Time frame: 0, 24 weeks
Changes in body weight
Changes in body weight assessed from baseline at 12 and 24 weeks
Time frame: 0, 12, 24 weeks
Changes in body mass index
Changes in body mass index assessed from baseline at 12 and 24 weeks
Time frame: 0, 12, 24 weeks
Changes in waist circumference
Changes in waist circumference assessed from baseline at 12 and 24 weeks
Time frame: 0, 12, 24 weeks
Concentration of thyroid stimulating hormone
measured by immunoassay
Time frame: 0, 12, 24 weeks
Concentration of thyroglobulin
measured by immunoassay
Time frame: 0, 12, 24 weeks
Concentration of Free Triiodothyronine
measured by immunoassay
Time frame: 0, 12, 24 weeks
Concentration of Thyroxine
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Empty capsules (placebo)
measured by immunoassay
Time frame: 0, 12, 24 weeks
Dietary iodine intake
estimated by food frequency questionnaire (FFQ)
Time frame: 0, 12, 24 weeks
Change in urinary iodine concentration (UIC)
Change in UIC assessed in pooled spot urine samples at 2 weeks, from baseline
Time frame: 0, 2 weeks