Bioavailability of Iodine in Cow's Milk in Swiss Adults (BICOM)

Iodine deficiency remains a global problem impairing health and development in affected populations. Although there has been remarkable global progress against iodine deficiency, mild and moderate iodine deficiency remain common globally, including European countries. Besides salt, milk and dairy products are important iodine sources in many industrialized countries, with varying contributions depending on the milk iodine concentration and the amount of milk and dairy consumed.

Iodine absorption in humans depends on the iodine species and possibly on the iodine status of the person. Very little data is available on iodine absorption or bioavailability from different dietary sources including milk. Inorganic iodide is thought to be absorbed almost completely (>90%). In contrast, only about two-thirds of some forms of organically-bound iodine are absorbed. The absorption of iodine from milk has not been quantified in humans. In this balance study, the investigators want to quantify the absorption of iodine in cow's milk in male and female adults and compare with the bioavailability from an iodine water solution (potassium iodide). The results of this study will inform on the bioavailability rate of iodine from cow's milk. Knowing the actual iodine bioavailability from milk is critical because milk and dairy products are major iodine sources in many industrialized countries.

The primary objective of this randomized, cross-over design study is to assess iodine bioavailability (measured using excretion in urine) from whole cow's milk delivering an iodine level of about 600 µg/L and compare them with a control iodine solution. The investigators will test three drinks within one subject: 1) a milk with an intrinsic iodine concentration of about 600 µg/L; 2) a milk with a naturally low iodine concentration and an added amount of potassium iodide (extrinsic iodine in milk matrix) to reach a level of about 600 µg/L (adapted to the intrinsic concentration in 1)); and 3) control iodine solution (extrinsic iodine in water matrix) with the same iodine concentration.

Study Overview

• Status: Completed
• Conditions: Iodine Bioavailability
• Intervention / Treatment: Dietary supplement: extrinsic iodine in milk; Dietary supplement: intrinsic iodine in milk; Dietary supplement: water iodine solution

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Zürich, Switzerland, 8092
    • ETH Zurich

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 41 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Aged between 18 and 45 years
2. BMI 19-25 kg/m2
3. Current use of iodized salt at home
4. Signed informed consent

Exclusion Criteria:

1. Inadequate iodine status (defined as UIC <70 µg/L or >300 µg/L and assessed during screening from 5 urine spot samples)
2. Exposure to iodine-containing X-ray/ computed tomography contrast agent
3. Use of iodine-containing disinfectants (betadine)
4. History of thyroid disease (according to the participants own statement)
5. Any metabolic, gastrointestinal or chronic disease such as diabetes, hepatitis, hypertension, or cancer (according to the participants own statement)
6. Chronic use of medications (except for contraceptives)
7. Use of iodine containing supplements within 1 month prior to study start
8. Pregnancy (according to the participants own statement but confirmed by a pregnancy test with the first urine spot sample from screening)
9. Breast feeding
10. Vegan diet
11. Drug abuse
12. Extensive alcohol intake, defined as more than 3 (men) or 2 (women) standard drinks per day (i.e. 3dl beer, 1dl wine, 3-4cl liquor), with less than 2 days per week without alcohol consumption

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: bioavailability iodine milk (extrinsic); 300 ml whole cow's milk delivering ≈ 200 µg iodine (extrinsic iodine in milk, low protein-bound fraction)	Dietary supplement: extrinsic iodine in milk; 300 ml whole cow's milk delivering ≈ 200 µg iodine (extrinsic iodine, low protein-bound fraction) The whole cow's milk will be produced in an experimental barn feeding supplementary iodine to reach a final iodine concentration of ≈ 50 µg/L. The iodine content of the extrinsically labelled milk will be adjusted to the required concentration (same as intrinsic iodine milk) by adding iodine in form of potassium iodide.
Other: bioavailability iodine milk (intrinsic); 300 ml whole cow's milk delivering ≈ 200 µg iodine (intrinsic iodine in milk, high protein-bound fraction)	Dietary supplement: intrinsic iodine in milk; 300 ml whole cow's milk delivering ≈ 200 µg iodine (intrinsic iodine, high protein-bound fraction) The whole cow's milk will be produced in an experimental barn feeding supplementary iodine to reach a final iodine concentration of ≈ 600 µg/L. This concentration will define final supplemental iodine given to the participants (adapting the total portion size).
Other: bioavailability water iodine solution; 300 ml water iodine solution delivering ≈ 200 µg iodine (water iodine solution)	Dietary supplement: water iodine solution; 300 ml water delivering ≈ 200 µg iodine (control)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Iodine concentration in urine	measured by Sandell-Kolthoff method, mikrograms per liter To calculate iodine absorption, excretion and retention.	Days 1, 2, 3, 8, 9, 10, 15, 16 and 17

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
TSH	thyroid function test at baseline	day 1
T4	thyroid function test at baseline	day 1
iodine content of standardized diet	the quantitative assessment of iodine content in the participants' standardized diet	prior to study start

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Age	Age in years	at screening
BMI	BMI calculated from measured weight and height	at screening

Collaborators and Investigators

• Sponsor: Isabelle Herter-Aeberli
• Investigators: Principal Investigator: Isabelle Herter-Aeberli, Dr., University of Zurich

Publications and helpful links

General Publications

• van der Reijden OL, Galetti V, Burki S, Zeder C, Krzystek A, Haldimann M, Berard J, Zimmermann MB, Herter-Aeberli I. Iodine bioavailability from cow milk: a randomized, crossover balance study in healthy iodine-replete adults. Am J Clin Nutr. 2019 Jul 1;110(1):102-110. doi: 10.1093/ajcn/nqz092.

Study record dates

Study Major Dates

• Study Start (Actual): June 18, 2018
• Primary Completion (Actual): September 27, 2018
• Study Completion (Actual): September 27, 2018

Study Registration Dates

• First Submitted: May 30, 2018
• First Submitted That Met QC Criteria: July 5, 2018
• First Posted (Actual): July 18, 2018

Study Record Updates

• Last Update Posted (Actual): March 8, 2019
• Last Update Submitted That Met QC Criteria: March 7, 2019
• Last Verified: January 1, 2019

More Information

Terms related to this study

• Keywords: bioavailability; milk; iodine
• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Anti-Infective Agents, Local; Anti-Infective Agents; Trace Elements; Micronutrients; Iodine; Cadexomer iodine
• Other Study ID Numbers: BICOM 2018-00130

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: Undecided

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No