Iodine Status and Thyroid Function of Vegans versus Non-Vegan AdultsKristen, Tony, Kelly, and Kelsie

Overview and Physiology

Essential for normal development and metabolism Controlled by thyroid gland

Major component of thyroid hormones (T3 & T4) BMR Macronutrient metabolism Muscle contraction Developmental growth Sexual maturation

Low hormone TSH release overstimulation of thyroid increased gland size (goiter)

Iodine Deficiency Symptoms:

Apathy Reduced mental functioning Lack of physical energy

During pregnancy: Spontaneous abortion Increase infant mortality Cretinism Cognitive defects

“Single most important preventable cause of brain damage worldwide” –World Health Organization

Dietary SourceFairly limited…

Table salt Sea-grown plants and animals Dairy products Some bread products Vegetables grown in soil w/ high iodine levels

Significance

Lack of primary research regarding US iodine status

Damaging effects of iodine deficiency Can be easily prevented with adequate intake

Our study will: Expand current findings Increase understanding of iodine status Study relationship between dietary choice

and iodine status Raise awareness of iodine status in developed

countries (US)

Significance

Hypothesis

Healthy vegan (diet excluding meat and dairy) adults aged 20-45 years will have poorer iodine status than non-vegan adults of similar age, gender and BMI.

This population may be at risk for negative subclinical effects on metabolic rate.

Objectives

Recruiting subjects from Missouri, we will test the above hypothesis by comparing iodine status and metabolic rate between young adult vegans and non-vegans.

Observational study

Specific Aims

24 hour urine iodine excretion Anthropometrics (body weight, height, waist

circumference, body composition) Fasting serum T3 and T4 levels Basal metabolic rate (indirect calorimetry) Dietary intake (24 hr diet record, food frequency

questionaire) Physical activity (Int’l Physical Activity

Questionaire)

Subjects Sample size =133 per group (between 20-45yrs old) Vegan: actively and consciously avoiding meat/dairy/eggs

and meat derivatives of any kind including fish and shellfish. For at least 6 months prior to study selection.

Non-Vegan: standard Midwestern diet (no required or voluntary dietary restrictions of meat, eggs, or milk food sources.

Location: Recruitment will occur in the city of Columbia, Missouri. Lab and anthropometric testing will occur in the McKee research laboratory site under supervision of professionals.

Recruitment/Selection

Flyers posted at local grocery stores and college campuses

$20.00 monetary incentive per subject upon completion

Testing will be in the winter College students would be gone in the summer Milk has more iodine in the winter due to shift from

grass feeding to iodine-enriched grain feeding of livestock

Gives opportunity to exacerbate any differences between the two groups

Exclusion Criteria

Vegan subject doesn’t meet all of criteria of vegan diet for at least 6 months prior to recruitment

Standard diet subject self imposes dietary restrictions of meat, eggs, or milk (or had in last 6 months)

Subject is diagnosed with a thyroid or iodine related illness in the last 5 yrs

Subject using vitamin/mineral supplementsFemale subjects who are pregnant or lactating

Screening/Methods

Baseline assessment (signing consent document) Answer food/medical history questions

Food frequency questionnaire

Height, weight, waist circumference, DXA, BMR (indirect calorimeter), International PA Questionnaire, 10mL blood draw (fasting serum T3 and T4 levels)

Subject will consume an iodine supplement, take home a 24hr urine iodine loading kit, and return after a recorded supplement ingestion time

24hr dietary recall using 5-step, multi-pass approach

Expected Results

Hypothesis: “Healthy vegan adults aged 20-45 years will have poorer iodine status than non-vegan adults of similar age and gender; and thus may be at risk for subclinical malnutrition”

Expected Results

Related Studies:1. Thomas Remer, Annette Neubert and Friedrich

Manz. British Journal of Nutrition 19992. Pearce EN, Pino S, He X, et al. Journal of

Clinical Endocrinology and Metabolism 20043. Swanson CA, Zimmermann MB, Skeaff S, et al.

Journal of Nutrition 2012

Limitations/ Confounders

Sample will come from Columbia, MO and may not be representative of total population

Urinary iodine test efficacy depends on adherence by subjects

Self-reporting subjectivity/ inaccuracy is possible