Iodine in our Diets and Cancer Risk

Unfortunately, most Americans are not getting enough Iodine. It is important to get the correct amount because it affects your thyroid function therefore your metabolism. Plus Iodine may help reduce the risk of our most frequent cancers: breast and prostate. (1)

Prior to 1920’s, around the Great Lakes, Appalachians and Northwest were known as the “goiter belt.” People had significant iodine deficient. 30-40% of the population had goiters as a result. (2) This decreased significantly when iodine was added to table salt.

Thereafter, Americans are getting most of their dietary iodine from table salt. 1/4 teaspoon of iodized table salt contains about 71 mcg iodine along with 575mg of sodium. We now tell people to reduce/avoid salt for health reasons.(4) Plus if your salt has been sitting around, the iodine added to your salt has an expiration date of 5 years from manufacturing date.

The amount of iodine you need each day depends on your age and health circumstance. Average Recommended Daily Allowance (RDA) amounts are listed below in micrograms (mcg). (3)

Life StageRecommended Amount
Birth to 6 months110 mcg
Infants 7-12 months130 mcg
Children 1-8 years90 mcg
Children 9-13 years120 mcg
Teens 14-18 years150 mcg
Adults150 mcg
Pregnant teens and women220 mcg
Breastfeeding teens and women290 mcg

Besides iodized table salt, other sources of Iodine in diet are: (mcg of iodine)(5)(6)(7)

  • Iodized salt: 1/4 tsp 71mcg
  • Kelp, 1/4 cup wet: 415 mcg or more. Amount is highly variable
  • Seaweed, dried, 1 ounce: up to 18,000 mcg. Amount is highly variable
  • Oysters (per 100gms): 160mcg
  • Canned salmon (per 100gms): 60mcg
  • Bread (except organic) (per 100gms): 46 mcg
  • Haddock, 3 ounces: 104-145 mcg
  • Cod, 3 ounces: 99 mcg
  • Shrimp, 3 ounces: 21-37 mcg
  • Processed fish sticks: 17 mcg per piece
  • Tuna, canned, 3 ounces: 17 mcg
  • Milk, 1 cup: 55-60 mcg
  • Cottage cheese, 1/2 cup: 25-75 mcg
  • Egg, 1 large: 18-29 mcg
  • Turkey breast, cooked, 3 ounces: 34 mcg
  • Ground beef, cooked, 3 ounces: 8 mcg

Other sources

  • Vitamins (prenatal, labelled content per daily serving): 75–200 μg4
  • Amiodarone (per 200 mg): 75,000 μg
  • Iodinated contrast (free iodine content, per CT scan): 13,500 μg
  • Topical iodine (povidone iodine): variable, usually 1–5%
  • Expectorants, mouthwashes, vaginal douches: variable
  • Saturated solution of potassium iodide (per drop): 50,000 μg

Not getting enough Iodine can be related to cancer. But so can too much. The Japanese have less breast and prostate cancer than Americans. (8) A possible explanation is that they consume a lot foods originating from the ocean. They consume up 10-100 times more iodine in their diet than Americans. (9)(10) Now I am not saying we should eat that much. The upper limits of Iodine ingestion is maximum 1,100 mcg of iodine per day. (3)

When you consume too little or too much, it likely will cause thyroid dysfunction and poorer health outcomes. How your thyroid is going to react is not predictable. There have been some cases of thyroid cancer in Japanese who consume too much iodine. (11)

The upper limits for iodine by age and health circumstance are listed below. These levels do not apply to people who are taking iodine for medical reasons and or under the care of a doctor.

Life StageUpper Limit
Birth to 12 months:Not established
Children 1-3 years:200 mcg
Children 4-8 years:300 mcg
Children 9-13 years:600 mcg
Teens 14-18 years:900 mcg
Adults:1,100 mcg

When consuming natural forms of iodine from diet, the amount consumed can’t be exact because nature is not exact. For example, Dulse flakes, a 3 gram (one tablespoon) serving equals 330% RDA, meaning a one teaspoon amount is all you should take per day. Hard to know how much exposure you get to heavy metals when eating things from the sea. Consuming it with cilantro and garlic may reduce the absorption of some of these heavy metals.

How your thyroid reacts to too much iodine is not predictable. Getting the Recommended Daily Amount is important.

(1) Pearce, E.N. (2015, Winter). Is Iodine Deficiency reemerging in the United States? Retrieved from https://journals.aace.com/doi/pdf/10.4158/EP14472.CO

(2) Meletis, C.D. and Zabriskie, N. (2007, Jun 29). Iodine, a Critically Overlooked Nutrient. Retrieved from https://www.liebertpub.com/doi/abs/10.1089/act.2007.13309?journalCode=act

(3) NIH, (2016, Feb 17). https://ods.od.nih.gov/factsheets/Iodine-Consumer/

(4) Leonard, J. (2018, Jul 30). Does pink Himalayan salt have any health benefits? Retrieved from https://www.medicalnewstoday.com/articles/315081.php

(5) Leung, A.M. and Braverman, L.E. (2013, Dec 17). Consequences of excess iodine. Retrieved from http:// https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3976240/

(6)Diet Health, Inc. Retrieved from https://www.diet.com/g/iodine

(7)Food Standards. (2019). Retrieved from http://www.foodstandards.gov.au/consumer/nutrition/iodinefood/Pages/default.aspx

(8) Kargar, S. and Shiryazdi, S.M. et al. (2017). Urinary Iodine Concentrations in Cancer Patients. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5464505/

(9)Rappaport, J. (2017, Jan 13). Changes in Dietary Iodine Explains Increasing Incidence of Breast Cancer with Distant Involvement in Young Women. Retrieved from http://www.jcancer.org/v08p0174.htm

(10) Zava, T.T. and Zava, D.T. (2011, Oct 5). Assessment of Japanese iodine intake based on seaweed consumption in Japan: A literature-based analysis. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204293/

(11) Michikawa, T. et al. (2012, May). Seaweed consumption and the risk of thyroid cancer in women: the Japan Public Health Center-based Prospective Study. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/22414981

American Thyroid Association. (2013, Jun 5). ATA Statement on the Potential Risks of Excess Iodine Ingestion and Exposure. Retrieved from https://www.thyroid.org/ata-statement-on-the-potential-risks-of-excess-iodine-ingestion-and-exposure/

https://www.veggiechallenge.com/concerns/vegetarians-veganssalt-high-blood-pressure-iodine-and-soy/

Advertisements

1 thought on “Iodine in our Diets and Cancer Risk”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s