Archive for the ‘Iodine’ Category

Arsenic in Kelp Supplements

Friday, October 26th, 2012

Just updated the Iodine page of regarding arsenic in kelp supplements:

“Most iodine supplements are simply tablets made from kelp. Being a seaweed, kelp likely contains at least small amounts of arsenic. There are some very rare cases in which people taking kelp supplements have developed symptoms of arsenic toxicity (8). A survey of kelp supplements in the U.S. found that eight out of nine batches contained some level of arsenic (8). Another survey in the UK of imported seaweed found very little arsenic in kelp, and no detectible amounts of inorganic arsenic, which is the harmful type (9).

“It is very unlikely that, taken at recommended amounts of 150 µg every other day, arsenic toxicity is likely to occur from kelp supplements. However, if you are concerned, at least one company makes iodine tablets that appear not to come from kelp: Nature’s Plus Potassium Iodide.”

Some additional notes:

The highest level of arsenic found in U.S. supplements was 65.5 mg/kg (8). My iodine supplement contains 225 µg of iodine in 45 mg of kelp. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has set a tolerable intake of 15 µg/kg of body weight per week (9). For a 140 pound person, that would be 953 µg per week. Supplementing three times per week with these tablets, at the highest toxicity level found, arsenic exposure would be 8.8 µg per week, well below the 925 µg level.

Wakame, kombu, and arame are all types of kelp.


8. Amster E, Tiwary A, Schenker MB. Case report: potential arsenic toxicosis secondary to herbal kelp supplement. Environ Health Perspect. 2007 Apr;115(4):606-8. Epub 2007 Jan 18.   |   Link | Follow-up letters to the editor.

9. Rose M, Lewis J, Langford N, Baxter M, Origgi S, Barber M, MacBain H, Thomas K. Arsenic in seaweed–forms, concentration and dietary exposure. Food Chem Toxicol. 2007 Jul;45(7):1263-7.   |   Link

Iodine and Acne

Friday, November 11th, 2011

Today’s post on the possible B12/acne link prompted me to ask if you’ve ever reviewed any literature on a link between iodine and acne. I began supplementing with iodine a few months ago–thanks to Vegan For Life, I realized I must be terribly deficient!–and I noticed a few weeks later that my skin was absolutely freaking out. I’ve dealt with adult acne pretty consistently for years but had things well under control with topical medication, and it seemed like something was really aggravating my skin all of a sudden. After googling around, I found a number of people claiming a link between iodine and acne, but I can’t tell whether any well-done studies have confirmed this. I’m well aware something else might have been causing my skin to flare, but I stopped taking the iodine and waited for my skin to calm down (which it has), and I plan to start with a very low dose of iodine and see if it happens again. I would love to know whether any good research supports a connection.

I had not previously reviewed the literature, as I had never heard of this before, but I reviewed it today (click for list of studies). Like B12 and acne, there is very little recent information. I was able to get copies of a couple letters from the Journal of the American Academy of Dermatology (Arbesman, 2005; Danby, 2007) in which there was a discussion about whether iodine in dairy could cause acne and they cited papers from the 1960s and 70s as evidence that iodine can cause skin problems.

A 1990 review of iodine toxicity reports says “…iodine intakes less than or equal to 1.000 mg/day are probably safe for the majority of the population, but may cause adverse effects in some individuals (Pennington, 1990).” The RDA is 150 micrograms per day.

It seems safe to say that iodine supplements could cause acne (or acne-like) skin problems for some people.

Iodine is not like B12 in that you should not try to catch up with a low iodine intake in the past. If your iodine intake was so low that you have hypothyroidism or a goiter, then you should see a doctor for supervision. But in terms of starting to supplement for optimal health, do not start with amounts more than we recommend in Vegan For Life or on, which is 75 – 150 micrograms every few days. Some iodine supplements have as much as 225 micrograms per tablet; in those cases I’d either break it in half or take it once every two three days.

So, I am scared to wonder what other supplement recommended for vegans might cause acne in some people. Vitamin D? Luckily, a quick search finds people claiming vitamin D cleared up their acne, rather than caused it!

(I do not know if the claims that vitamin D can clear up acne have any validity.)


Arbesman H. Dairy and acne–the iodine connection. J Am Acad Dermatol. 2005
Dec;53(6):1102.   |   Link

Danby FW. Acne and iodine: reply. J Am Acad Dermatol. 2007 Jan;56(1):164-5.   |   Link

Pennington JA. A review of iodine toxicity reports. J Am Diet Assoc. 1990
Nov;90(11):1571-81. Review.   |   Link Update: Iodine

Monday, November 7th, 2011

Can you get a blood test to determine if you have enough iodine in your system?

No, there is no common test to determine how much iodine you have in your body. The American Thyroid Association discusses this in their article Iodine Deficiency.

I added a link to that article from the Iodine page on

If you have no idea if you get enough iodine, please check out the links!

Iodine in Vegans

Tuesday, June 28th, 2011

Just updated the Iodine page at The important new info (thanks, Lisa!) is this study:

In a 2011 cross-sectional study from the Boston area, urinary iodine levels of 78 lacto-ovo vegetarians and 62 vegans were measured (1). People with previously diagnosed thyroid problems were excluded from the study. According to the authors, “Population iodine sufficiency is defined by median urinary iodine concentrations 100 µg/l or greater in adults and 150 µg/l or greater in pregnancy.” Median urinary iodine concentration of vegans (79 µg/l; range 7 – 965 µg/l) was significantly lower than vegetarians (147 µg/l; range 9 – 779 µg/l). Markers of thyroid function were similar in both groups and in the normal range; one vegan and no vegetarians had abnormal thyroid function. Most of the vegans were making no effort to insure adequate iodine intake.

So, it appears that vegans have not yet gotten the message about the importance of iodine (or most are not taking heed). It’s a good thing that only one showed abnormal thyroid function given how low the average was.

My recommendations are to take 75 to 150 µg of iodine every few days.


If you are interested in bodybuilding, Vegan Bodybuilding & Fitness is a great read! It is written by Vegan Outreach supporter, activist, and The World’s Most Recognized Vegan Bodybuilder, Robert Cheeke.


1. Leung AM, Lamar A, He X, Braverman LE, Pearce EN. Iodine Status and Thyroid Function of Boston-Area Vegetarians and Vegans. J Clin Endocrinol Metab. 2011 May 25. [Epub ahead of print] Link

Hair Loss and Iodine

Thursday, March 31st, 2011

Personal update: I have, for all intents and purposes, finished the article on soy that I worked on for over 3 months. But, it is not yet live. I’m hoping it will be soon. In the meantime, I’m getting to the back log that built up during the time I was working on it.

And without further ado, here is some information on hair loss and iodine:

QuasiVegan’s post Hair Loss on the Vegan Diet, brought my attention to the fact that thyroid problems can cause hair loss, something that I was not aware of previously.

I have updated the article, Hair Loss, with the following:

Summary: Occasionally, women who become vegetarian or vegan report experiencing hair loss. If there is a dietary cause, the most likely are rapid weight loss, thyroid problems, or iron deficiency. Zinc deficiency and not getting enough of the amino acid lysine could also be culprits.

According to Mayo Clinic, an overactive or underactive thyroid gland can lead to hair loss. Upon going vegetarian or vegan, people might increase their soy intake. Soy can affect the thyroid, especially when iodine levels are not adequate or someone is predisposed to thyroid problems. Making sure you get enough iodine, by taking 75 to 150 µg per day from a supplement, should prevent any hair loss problems that could be due to iodine or soy. If you are predisposed to thyroid problems, limiting soy might also help.