iodine

rda of iodine

m & f: 150 mcg/d

preg: 220 mcg/d

lac: 290 mcg/d

food sources of iodine

marine life/seafood

dairy foods: cow's milk

kelp/kombu/brown seaweed algae

how much seaweed should be consumed/limited to, especially for pregnant women and children

1 serving/week

where is iodine mainly absorbed

stomach/duodenum

what is iodines absorption rate

\>90% (greater than 90%)

t/f: kidneys have no mechanism to conserve iodine

true

thyroid gland functions

influences:

\-metabolism

\-protein synthesis

t/f: T4 and vitamin A play a big role in transcription of certain genes

false, T3 and vit A

what is dietary iodine typically bound to

amino acids, or found free

names of the thyroid hormones

T3: triiodothyronine

T4: thyroxine

functions of thyroid hormones

they help to regulate body functions

T3

triiodothyronine

T4

thyroxine

t/f: iodine cannot be absorbed through the skin

false

what happens if iodine is bound to amino acids

iodine is released

t/f: iodine is capable of entering through all tissue

true

t/f: free iodine appears in the bloodstream

true

where is iodine mainly found

in the thyroid gland

TRH

thyrotropin releasing hormone

TSH

thyrotropin/thyroid stimulating hormone

what hormone does the hypothalamus release

thyrotropin releasing hormone (TRH)

what hormone does the pituitary gland release

thyrotropin/ thyroid stimulating hormone (TSH)

how does t3 and t4 move throughout the body

in the blood bound to proteins

what proteins bind to t3 and t4 to transport them

thyroxine binding globulin

albumin

transthyretin (prealbumin)

t/f: transthyretin (prealbumin) is a transporter of iodine and vitamin A

true

what is transthyretin

prealbumin, a transporter of iodine and vit a

actions of thyroid hormones

regulation of body temp

brain maturation (fetal neurodevelopment)

protein synthesis (tissue growth)

enhances lipolysis

free fatty acid (FFA) metabolism

glycolysis

glycogenesis

transcription

where does thyroglobulin originate

thyroid gland

what is thyroglobulin

a protein made by the thyroid gland

what other nutrients does iodine interact with

vitamin A, iron(Fe), selenium (Se)

why is vit a important related to iodine

important for the uptake of iodine into the thyroid gland

why is iron and selenium important related to iodine

they aid in the production of thyroid hormones

what hormone aids in the production of thyroid hormones related to iron

thyroid peroxidase

what hormone aids in the production of thyroid hormones related to selenium

5-deiodinase

selenium rda

m&f 14-70: 55 mcg/d

food sources of selenium

brazil nuts (90)

tuna (55)

shrimp (42)

beef (33)

chicken (26)

what are goitrogens

substances that interfere with iodine metabolism to INHIBIT thyroid hormonogenesis, can be food.

what can goitrogens affect

iodine uptake by the gland

production of thyroid hormones t3 and t4

hormone release from the thyroid cells

examples of goitrogens

glucosinolates

goitrin

lithium

examples of glucosinolates

cruciferous vegetables/brassica (types of plants)

cabbage

broccoli

kale

cauliflower

collard greens

brussel sprouts-high intake of these may cause hypothyroidism

goitrin

found in cassava and is consumed largely in 3 world countries

lithium

used in medications for severe depression or bipolar disorder when others don't work

populations that may be deficient in iodine

vegans

low salt diet

lactose deficient

preg/lac

certain areas of the world

t/f iodine status in the us is considered sufficient

true

t/f some studies have indicated that 1/3 of all preg women in the us have iodine deficient diets

false, 1/2

t/f the iodine content of prenatal mvi is mandated in the us

false, they are not mandated-it is estimated only 1/2 of marketed prenatal vitamins in the us contain iodine

what do thyroid hormones influence in fetus development

metabolism

expression of genes

what physiological functions do thyroid hormones influence in fetal development

embryogenesis

growth and development of the body

neurological and cognitive function

what does t3 regulating cell differentiation and gene expression impact

it impacts:

neuronal proliferation

neuronal migration

neuronal organization

\-this affects the multiplication, migration, and myelination of glial cells (nervous cells together)

how were iodine deficiency disorders defined

they were made to encompass ALL the effects of iodine deficiency

iodine deficiency problems

hypothyroidism

goiter

impaired cognitive development (fetus)

cretinism (learning disabilities, foolishness, or stupidity)

\-cretinism is the extreme end of a continuum of iodine deficiency

what are symptoms of cretinism

hypotonia (loss of muscle)

thick, increased tongue

poor feeding habits

short physique

what is hypothyroidism

the thyroid is unable to produce enough thyroid hormone

what are indicators of hypothyroidism

high levels of TSH and low levels of thyroid hormone

symptoms of hypothyroidism

slower speech or movement

swollen thyroid gland

hoarse voice

puffy face

heavy menstrual bleeding or irregular periods

muscle joint/pain

difficulty thinking and focusing

feeling depressed

forgetfulness\*\*

low energy

muscle weakness

constipation

brittle fingernails

swollen legs, ankles, or feet

weight gain\*

the influence of diet on thyroid hormone regulation

people are dissatisfied with traditional treatment and causes them to explore other options, this can lead them to find inaccurate information not helping their condition or even worsening it

scientific findings of considerations for diet interventions

get adequate se, fe, and I intake

avoid fasting-leads to decreased t3 levels

calorie/cho intake inc. t3 production

high intake of cruciferous veggies can inhibit iodine uptake

iodines upper level/limit (UL)

m&f 19+: 1100 mcg/d

\-could be higher, this rec is on the conservative side.

what does the American Thyroid Association recommend regarding supplements

they are against the ingestion of an iodine or kelp daily supplement containing \>500 mcg of iodine for all individuals except for certain medical conditions

symptoms of acute iodine toxicity (one big dose)

burning of the mouth, throat, and stomach

nausea, diarrhea, vomiting and fever(schmidts story)

chronic iodide toxicity (accumulating over time)

may inc. the risk of thyroid disorders

iodine induced goiter

thyroid autoimmunity

hypothyroidism

hyperthyroidism