Iodine: what is the safest level to consume
Iodine
is an essential mineral the body needs to synthesize thyroid hormones and for
proper thyroid function. Iodine deficiency can cause goiters, which are enlarged
thyroid glands. However, consuming too much iodine can cause gastrointestinal
issues and, in severe cases, acute toxicity. Since consuming too little iodine
and too much iodine both pose consequences, there is an ongoing debate about
what the recommended level of iodine intake should be per day. With iodine
inadequacy on the rise in the US, many are suggesting that it needs to be
raised; others say that raising the recommended amount would put more people at
risk for acute toxicity and other issues. According to the American Thyroid Association, adults should
consume about 150 mcg per day and not exceed 1,100 mcg per day, which is the
established tolerable limit. This raises the question of where do we draw the
line?
Iodine has been removed from many sodium sources in the American
diet. One major area is highly processed foods; consumption has risen
exponentially in recent years. According to the CDC, individuals 1 year of age
and older obtain 55% of their calories from processed foods. Sodium is a major
ingredient in many processed foods, but iodized salt costs more than
non-iodized salt, so companies choose the cheaper option, removing a source of
iodine from our diets. Eating non-iodized salt won't cause an iodine deficiency.
While most Americans aren’t severely deficient, iodine inadequacy is increasing.
A study published in the Journal of Nutrition examined iodine inadequacy in the
United States from 2001 to 2018 and found that it doubled. They found that
iodine intake decreased by 24% in females and 22% in males, suggesting people
are not ingesting enough iodine to maintain normal levels and contributing to
the growing rate of iodine inadequacy in the United States (Lieberman et al.,
2025). This will continue to rise as companies opt for non-iodized salt and use
specialty salts without iodine. People are also changing their diets to low
sodium, low cholesterol, low fat, low carb, and so on. These dietary choices
directly affect how much iodine you consume. One great source of iodine is
eggs; fewer people eat eggs because they want to lower their fat and
cholesterol intake. Another great source of iodine is cow’s milk; people have
either gone non-dairy or just have started consuming dairy at much lower rates.
Eggs contain roughly 31 mcg per egg, and milk contains 84 mcg per cup. These
are excellent sources of iodine and would get everyone to roughly 115 mcg at
the start of the day.
Iodine deficiency was once thought to
be eradicated in the US, but as inadequacy levels rise, it may soon return.
This is one major reason people want to raise the required iodine intake; they
believe it doesn't account for iodine loss from our diets. They also believe
this low level is a reason for the rise of thyroid-related diseases in the US.
Where this level once was believed to cover all the bases for thyroid health,
it is now believed to lower only the risk of developing a goiter. It is now
thought that people need more iodine in their diets to support proper thyroid
function, brain function, and development.
The
way some people combat this loss is through unregulated supplement use. They
take high-dose iodine supplements, which typically contain 150 mcg according to
the American Thyroid Association, or eat sea moss every morning, believing they
are doing something good for their health. People take sea moss as a natural
seaweed supplement because it’s been marketed as a “superfood.” That’s all it is:
marketing. Ingesting sea moss can have more negative side effects than positive
ones, including acute iodine toxicity if you don't monitor your daily iodine
intake. According to an article posted by Organics Nature, a serving of sea
moss gel can range from 56 mcg to 98 mcg; this range depends on the type of sea
moss you are ingesting and how it was processed. Taking sea moss or an iodine
supplement on top of your normal iodine intake can cause problems, especially
if you don't track how much iodine you are ingesting throughout the day. Overconsumption
of iodine is just as bad as iodine underconsumption; it is a balancing act.
As someone whose family uses pink Himalayan salt instead of iodized salt and rarely cooks with salt in general, I believe there is enough evidence to warrant looking into raising the recommended level to ensure everyone gets the right amount of iodine in their diet. The recommended intake may meet people’s needs, but it may not be sufficient for everyone. Dietary changes and the rising rate of iodine inadequacy suggest people need more iodine than they realize. Instead of recommending supplements, efforts should focus on encouraging people to eat iodine-rich foods. I believe we can add it back into food without harming people, and it can also help prevent inadequacy and deficiency. So, if it can help keep people safe, why not add it back into food and raise the recommended daily level?
By Lillian Meier, A Master's of Medical Science student at the University of Kentucky
References
https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/
https://www.webmd.com/diet/health-benefits-sea-moss
https://experiencelife.lifetime.life/article/why-is-iodine-controversial/
Khudair A, Khudair A, Niinuma SA, Habib H, Butler AE.
Beyond thyroid dysfunction: the systemic impact of iodine excess. Front
Endocrinol (Lausanne). 2025 Apr 2;16:1568807. doi: 10.3389/fendo.2025.1568807.
PMID: 40241991; PMCID: PMC11999837.
Lieberman,
H. R., Mathews, R. S., & Fulgoni, V. L., III. (2025). Iodine inadequacy
is prevalent and has continuously increased from 2001 to 2018 in the United
States. The Journal of Nutrition, 155, 3886-3895. https://doi.org/10.1016/j.tjnut.2025.09.017
https://www.cdc.gov/nchs/products/databriefs/db536.htm
AI was used to edit for clarity and create citations.
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