Seaweed, the Food Matrix, and Iodine Bioavailability

Iodine Bioavailability Clinical Trial

— IoBio  

Official title:

Seaweed, the Food Matrix, and Iodine Bioavailability

Clinical Trial Details — Status: Not yet recruiting

Administrative data

• NCT number: NCT04867291
• Other study ID #: 200180075
• Status: Not yet recruiting
• Phase: N/A
• Start date: April 2021
• Est. completion date: November 2021

Study information

• Verified date: April 2021
• Source: University of Glasgow
• Contact: Martha L Redway, BSc
• Phone: 07510924724
• Email: m.redway.1[@]research.gla.ac.uk
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This study explores the influence of the food matrix of seaweed-containing food products on iodine bioavailability. The investigation will ascertain whether iodine bioavailability (as a percentage of the dose ingested that is excreted in urine) is comparable between seaweed sheets, seaweed powder (in capsules), pizza fortified with powdered seaweed, and potassium iodide supplements.

Description:

Iodine deficiency can have serious consequences, especially during pregnancy and lactation where the fetus is entirely dependent on its mother for the provision of iodine. There is no current iodine fortification programme in the United Kingdom, and the main sources of iodine are from dietary sources, such as dairy products and seafood. However, seaweed is also a rich source of iodine; the inclusion of iodine (via powdered seaweed) in commonly consumed foods is of potential benefit as a strategy, as it removes the need for consumers to alter their dietary behaviours, which are often culturally standardized.

Seaweed intake (via supplements) can increase the iodine status of women with habitually low-iodine diets. However, reduced bioavailability of iodine from the seaweed matrix has also been displayed, which could impact iodine intake should individuals choose to use seaweed as a dietary source of iodine.

This study tests the influence of the food matrix of seaweed-containing products on iodine bioavailability. This will be evaluated over the course of 27 days, in a randomized crossover trial design with 4 arms. Each arm will be separated by 7 washout days, and participants will follow a low iodine diet (avoiding all seafood, seaweed products, eggs, dairy, fortified plant milk and goitrogens (cabbage, soy etc.) for the 2 days preceding and the 1 day following each feed.

1. Food arm: portion equivalent to 200µg of iodine, half a pizza (Eat Balanced pizza) (consumed with ~450mL of water)

2. Seaweed sheet arm: portion equivalent to 200µg of iodine, ~10g of seaweed sheets (consumed alongside 2 slices of white bread and ~450mL of water)

3. Seaweed powder arm: portion equivalent to 200µg of iodine, 1 capsule (consumed alongside 2 slices of white bread and ~450mL of water).

4. Potassium iodide supplement arm: portion equivalent to 200µg of iodine with ~450mL of water (Piping Rock Potassium Iodide Supplement, consumed alongside 2 slices of white bread)

Iodine excretion will be monitored in urine collected during the 12 hours preceding and 36 hours following the meal. Urine will be collected in 8 timed fractions (0-1h, 1-2h, 2-3h, 3-5h, 5-8h, 8-12h, 12-24h, 24-36h) and participants will be provided with containers and instructions on how to collect their urine. A single fecal sample will also be collected before the first feed, and within 24 hours of all feeds. Participants will also keep a detailed food diary on all study days to enable iodine ingestion monitoring.

Recruitment information / eligibility

• Status: Not yet recruiting
• Enrollment: 12
• Est. completion date: November 2021
• Est. primary completion date: November 2021
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Female
• Age group: 18 Years to 48 Years

Eligibility

Inclusion Criteria:

• Healthy

• Premenopausal women

• 18-48 years old

• Signed informed consent

Exclusion Criteria:

• Pregnancy and lactation

• Past and present thyroid conditions/dysfunction

• Allergy to gluten, wheat, or dairy

• Iodine supplement consumption

• Currently taking medication (other than contraceptive)

• Diseases of the gastrointestinal tract

• Current smoker

• Current vegan (pizza contains dairy cheese)

• Having a habitual diet very low in iodine (<1 portion of dairy per day, or <1 portion of fish per week)

• Having a habitual diet very high in iodine (>4 portions of dairy per day, or >4 portions of fish per week)

Related Conditions & MeSH terms

• Iodine Bioavailability

Intervention

Dietary Supplement:
• Pizza
Portion equivalent to 200 µg of iodine (half a pizza), consumed with ~450mL of water.
• Seaweed Sheets
Portion equivalent to 200 µg of iodine (~10g), consumed with two slices of white bread and ~450mL of water.
• Seaweed Powder
Portion equivalent to 200 µg of iodine (1 capsule), consumed with two slices of white bread and ~450mL of water.
• Potassium iodide
Portion equivalent to 200 µg of iodine (1.3 tablets), consumed with two slices of white bread and ~450mL of water.

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
University of Glasgow

Outcome

Type	Measure	Description	Time frame	Safety issue
Other	Gut Bacterial Diversity	Assessed via single fecal sample	Prior to commencement of trial
Other	Seaweed Fermentation Capacity	Assessment of the capacity of participants' gut microflora to ferment seaweed polysaccharides and release iodine from the food matrix. Assessed via single fecal sample used in an in vitro fermentation model.	Prior to commencement of trial
Primary	Urinary Iodine Excretion (micrograms/L)	The percentage of iodine ingested from the test foods that is excreted in the 36 hours following test food ingestion will be measured in urine collected fractions: 1-2, 2-3, 3-5, 5-7, 7-12, 12-24, 24-36 hours	36 hours
Secondary	Fecal Iodine Excretion (micrograms/g feces)	The percentage of iodine ingested from the test foods that is excreted in a single fecal sample passed in the 24 hours following test food ingestion	24 hours