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[A1CR]

OK, time to send everyone into a panic again ...

So I went for an annual lab test a while back, including a partial thyroid panel. The archetypal thyroid hormonal pattern for CR is that TSH should be more or less normal, with low or normal T4 and low T3. This is what I've previously had. But now, all of a sudden I've got a skyrocketing TSH. This is not good!

Now, TSH typically becomes elevatd as the body screams out for thyroid hormones which are not being produced. CR folks have low thyroid hormones (esp T3), but TSH shoudl NOT be elevated, because this low T3 is a REGULATED downregulatioin -- the body doesn't WANT more T3 (tho' cold-handed CR folk might disagree). But there are of course other, PATHOLOGICAL causes of low T3 & high TSH.

Iodine deficiency is one of them, because the body needs iodine to make thyroid hormones; indeed, folks who've been with us for more than a few months will recall that Dean had had a high TSH and had solved his problem with an iodine supplement. I used to take one of these with my multi, but I haven't taken a multi for years because they're all in some sense IMO quite bad for one (bone-toxic (>1500 IU) doses of retinol/retinyl esters; synthetic beta-carotene; excessive Zn:Cu (which, ironically, is exactly what I *personally* need); and (on a paranoid-speculative basis, based on the work on sirtuins) niacinamide (which directly inhibits sirtuins -- as vs niacin)).

Even quite conservative nutritional authorities recognize that "Vegetarians... or persons on low salt diet are liable to develop dietary iodine deficiency and therefore need iodine supplements." (1) I thought that my iodine was adequate because I've been consuming kombu (true kelp). Unfortunately, I've never had any way to be quite sure how much iodine this gives me, as there's no entry for iodine in kelp in the USDA database. Plus, I consume a lot of cruciferous vegetables, which contain isothiocyanates, which are at once anticarcinogens & potentially goitrogenic compounds, & it ocurred to me that since my last thyroid panel I've been cooking these vegetables less & taking more care to cut them up & let 'em rest first -- steps which increase the liberation of same from their bound (glucosinolate) forms in the cell.

But I was reluctant to just start popping an iodine supplement with no idea as to how mch I was already getting from food, on the basis that I might do myself some harm from EXCESS iodine. As was mentioned by Al a while ago, it is possible to get high TSH as a result of overstimulation from excess iodine, tho' it's not clear exactly how this happens. I did a fair amount of reading on this, & I won't post the whole massive mess of stuff, but the gist is delivereed in this comment from the Linus Pauling Institute:

"excess iodine intake is most commonly associated with elevated blood levels of thyroid stimulating hormone (TSH), hypothyroidism, and goiter. ... [E]levated TSH levels have been found at iodine intakes between 1,700 and 1,800 mcg/day. In order to minimize the risk of developing hypothyroidism, the Food and Nutrition Board (FNB) of the Institute of Medicine set a tolerable upper level of intake (UL) for iodine at 1,100 mcg/day for adults."

http://lpi.oregonstate.edu/infocenter/minerals/iodine/

Folks wanting fairly extensive documentation can review the "Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Iodine" for the EU Commission (1), available online. I can also email folks an edited bunch of highlights from this document I'd prepared along the way as I read.

Initially, these numbers encouraged me to think that I had plenty of wiggle room: the UL is nearly 8 times the DRI -- & my only recognized major source was just this one. I actually started calling around town looking for a stand-alone iodine supplemetn accordingly. But then, in the course of the above research, I came across the fact that goiter has historically been endemic in areas of high seaweed consumption in Japan -- due to excess iodine intake.

See eg. (5), which is primarily about goiter due to iodine DEFICIENCY, mentions the normal ANTI-iodine goitrogens, but lists seaweed among goitrogenic compounds. See also (6), where coastal Japanese populations consuming "a diet containing kombu" wound up consuming "a daily intake of more than 28 mg/day of iodine," apparently leading to "iodine-induced thyrotoxicosis"; see also discussion of the phenomenon in (1), and the brief mentions in popular articles (7).

So I went looking with renewed vigor for proper data on my likely iodine exposure from kombu-type kelp. I had a rather frustrating time at this, having found quite a few alleged numbers online, which cover an irritatingly wide range, giving one no confidence in any one of them. But it rapidly became obvious that in all probability I've been poisoning myself with the stuff for years.

I've been putting 2 strips of kombu into each of my various stew meals except the Mulligatawny, so that (since each such recipe makes 6 servings) I consume ~1/3 of a strip -- or 1.16 g -- every day. This is in fact roughly what Dr. Walford recommends for use in stews, perhaps on the assumption that people would rarely consume same (_Anti-Aging Plan_, pg 95) -- yet it is placed in a section of "Nutrient Super-Chargers", "nine foods that easily boost every recipe they are added to," (pg 94) suggesting that they're appropriate to be a regular dietary staple at this dose. ('Course, he also lists dry milk, soybeans, tofu, and wheat germ among the favored 9 ... brr!).

The problem is to determine how much I this is. There's no USDA database entry for this, & I found an irritatingly wide range of values on the Web (I've appended a bunch of snippets at the very end of this email, after the ferences, for interested parties). The only peer-reviewed source I found was (2), which says unhelpfully that "Edible seaweed contained I levels of between 4300 and 2,660,000 micrograms/kg"; this would then be between just 5 to as much as 3103 micrograms/day.

In an email from the International Council for the Control of Iodine Deficiency Disorders < http://www.people.virginia.edu/~jtd/iccidd/ > I was told that "Seaweeds vary greatly in their iodine content. An older reference states that Kombu contains 0.8 to 4.5 g iodine per kg dried material (Hiroshi, in Stanbury and Hetzel Endemic Goiter and Endemic Cretinism, Wiley, 1980, pg. 244)." So this could be anywhere from an already-borderline 928 to an astounding 5220 mcg every day for years, now.

And I got confirmation of the HIGH end of this range from a worman from the Nutrition Division of the UK Food Standards Agency (which I emailed) cited (3) for the following information: "Seaweed, kombu, dried, raw" iodine value of 440 670 mcg/100g. This evidently authoritative source would thus peg my iodine intake at a whopping 5111 mcg/day!

In light of this, Walford's casual endorsement, & the common advice to veg(etari)ans to use kelp as a regular iodine source, is ignorance or madness. Anything more than a little crumble in a dish is likely to cause you problems. Even the Vegan Society's advice that "because they are both so high in iodine, a half ounce of kombu or three and a half ounces of hijiki should last you about a year" < http://www.findarticles.com/cf_dls/m1594/5_12/77749311/print.jhtml >

... which I read early on in my hunt & thought alarmist at the time, is in fact more than you need to eat the RDA of iodine every day for the entire year (0.5 oz ~ 14 g to moderns). (Hell, I've been eating my way thu' several 50 g packages a year!).

Yes, this is nuts. Right now, I've got what looks like a bad scenario: low T3 (which is hard to disentangel from CR) but also low T4 (wich isn't NECESSARILY to be taken as just normal for CR), & v. high TSH (definitely not normal for humans under CR, & a likely step along the way to Bad Things). One cannot even solve the problem in existing foods by picking out the kombu: "Ninety-nine % of the iodine was found in water after 15 min boiling." (4) For existing food, you either have to throw it out, or perhaps put it aside and consume maybe one such 'contaminated' dish a WEEK until it's gone.

Some are more vulnerable to the problem than others: "Individuals with underlying autoimmune thyroid disease, those with a previous history of postpartum thyroiditis or subacute thyroiditis, or patients who have undergone partial thyroidectomy have all been shown to be prone to iodine-induced goiter and hypothyroidism" (8 ).

While it's reasonably clear why iodine DEFICIENCY can lead to hypothyroidism (I is the limiting factor for the synthesis of T4, which is then converted peripherally to T3), the explanations given in various sources for thyroid dysfunction related to EXCESS iodine are much vaguer. "[A]lthough the natural history of thyroid dysfunction related to acute excess iodine ingestion has been well characterized, the effects of chronic iodine excess remain poorly understood."(8 ) "[T]he mechanism for goiter formation remains unclear. It has been suggested that an increase in lymphoid infiltration or a mild chronic rise in TSH may be responsible. " (8 )

There are several possible hazards to the thyroid which can follow from iodine toxicity (8 ): "Previously published reports have described both subclinical and overt thyroid dysfunction as a result of excess iodine ingestion. Goiter, hypothyroidism, and/or a rise in serum TSH values have been reported to result from ingestion of excess iodine". (8 ) "Acute excess iodine ingestion has long been known to result in a transient decrease in iodine organification [ie, organic binding & incorporation of same into T4], termed the acute Wolff-Chaikoff effect." (8 )

"There was a high prevalence of goiter among Peace Corps volunteers in this study at baseline in both euthyroid and hypothyroid individuals." (8 ) However, excess iodine "resulted in a VARIETY of thyroid abnormalities [my emphasis]. During the prolonged excess iodine exposure there were marked increases in serum total iodine concentrations, and the prevalence of goiter, elevated serum TSH values, and elevated serum TPO antibody values increased". Anti-TPO is a bad thing, indicating autoimmune attack on the thyroid, & this is the grimmest possibility."In one histological study of the thyroid glands of 28 Japanese patients chronically exposed to excess dietary iodine, 13 had lymphocytic infiltration, and 25 had moderate to marked follicular hyperplasia" (8 ) -- agin, lymphocyte infiltration would be amarker of autoimmune attack.

"Although individuals with underlying autoimmune thyroid disease are more likely to develop complications of excess iodine ingestion, it is unclear whether excess iodine ingestion itself can lead to autoimmune disease. Animal studies have suggested that excess iodine exposure predisposes to the development of autoimmune thyroid disease [ref]. However, controversy exists about whether there is a relationship between excess iodine ingestion and the development of Hashimoto’s thyroiditis in humans [ref]. It has been observed that in areas of Japan where dietary iodine intake is high, the incidence of Hashimoto’s thyroiditis is higher than in areas of low to normal dietary iodine intake [ref]. An increase in lymphocytic infiltration often occurs after iodine repletion in iodine-deficient regions[ref]. However, other studies have failed to show a relationship between increased iodine intake and autoimmunity [refs]". (8 )

So, what's the prognosis? In the case of the ACUTE problem of the Wolff-Chaikoff effect, "With sustained excess iodine exposure ... most individuals’ thyroid glands ... resume synthesis of normal amounts of T4 and T3. The mechanism responsible for this escape or adaptation to the iodine load probably involves a decrease in the Na+/I- symporter protein, resulting in a decrease in thyroid iodide content[ref]. In some individuals this escape phenomenon does not occur, and those patients develop iodine-induced hypothyroidism. Such hypothyroidism generally is reversible when the source of excess iodine exposure is removed."

This sounds optimistic -- except that I imagine that this adaptation may be why my previous tests have come out OK; the current rocketing of my TSH suggests the disturbing possiblity that this metabolic adaptation has failed -- perhaps in a manner analogous to type 2 diabetes, where the body adapts to the initial insulin resistance by compensatory increases in insulin secretion, which temporarily sustains glucose in the normal range, but which ultimately fails when the overburdened pancreas finally gets burned out.

In the Peace Corps volunteers in (8 ), "The prevalence of all abnormalities decreased after removal of excess iodine from the drinking water system." "In this study some Peace Corps volunteers had anti-TPO antibodies during excess iodine exposure. These abnormal TPO antibody titers decreased in some, but not all, subjects when excess iodine was eliminated. This suggests that excess iodine ingestion may induce thyroid autoimmunity in an otherwise healthy young population."

Yikes. Yes, I'm getting an anti-TPO test in a couple of months.

Anyway: people should know about this. One simply must either not use this stuff at all, or put just a tiny fragment of the stuff into a multi-serving recipe. I tell ya, between thyroid damage from kombu, dementia from tofu, possible autoimunity from wheat germ ... I begin to identify with the gits I talk to who are always arguing that the findings of nutritional science are so inconsistent that one may as well just eat whatever the hell appeals to one. It's not true, but (a) the reality of "swallow the whole pill" is much more difficult to explain to people, and (b) one DOES certainly have to have the basic TOXICOLOGICAL data to hand -- as in this case or the retinol/bone fracture thing.

Grr.

-MR

1: "Opinion of the Scientific Committee on Food on the Tolerable Upper Intake Level of Iodine" for the EU Commission. http://europa.eu.int/comm/food/fs/sc/scf/out146_en.pdf

This link was toast last time I checked, but the Google cache was working fine:

http://www.google.ca/search?q=cache:4sgg0rQGTzIJ:europa.eu.int/comm/food/fs/sc/scf/out146_en.pdf+ul+iodine+t3+t4+tsh+references&hl=en&ie=UTF-8

2. Lee SM, Lewis J, Buss DH, Holcombe GD, Lawrance PR. Iodine in British foods and diets. Br J Nutr. 1994 Sep;72(3):435-46. PMID: 7947658 [PubMed - indexed for MEDLINE]

3. The Vegetables, Herbs and Spices supplement to the 4th edition includes an entry for Seaweed, kombu, dried, raw and gives an iodine value of 440 670mcg/100g.

3. Food Standards Agency (2002) McCance and Widdowson's The Composition of Foods, Sixth summary edition. Cambridge: Royal Society of Chemistry. Price: £45. ISBN 0-85404-428-0.

4. Ishizuki Y, Yamauchi K, Miura Y. [Transient thyrotoxicosis induced by Japanese kombu] Nippon Naibunpi Gakkai Zasshi. 1989 Feb 20;65(2):91-8. Japanese. PMID: 2744193 [PubMed - indexed for MEDLINE]

5. Lisboa HR, Gross JL. Ultrasonographic determination of goiter prevalence in southern Brazilian schoolchildren. Braz J Med Biol Res. 2002 Oct;35(10):1147-52. Epub 2002 Oct 13. PMID: 12424486 [PubMed - indexed for MEDLINE] http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2002001000006&lng=en&nrm=iso

6. "Goiter induced by high iodine intake has also been documented in Japan, where seaweeds rich in iodine (up to 4.5 mg/g dry weight) are consumed. Some individuals there consume as high as 50-80 mg iodine/day." http://www.naturalhealthnotebook.com/Health_Problems/Goiter.htm

7. " Excessive intake of iodine may result in a condition known as "iodine goiter." This type of goiter is characterized by an enlargement of the thyroid gland and might be erroneously diagnosed as goiter resulting from insufficient iodine intake. This condition is prevalent in Hokkaido, and island in norther Japan, where dietary intake of iodine rich seaweed and kelp are far in excess of RDA standards." http://www.springboard4health.com/notebook/min_iodine.html

8. Pearce EN, Gerber AR, Gootnick DB, Khan LK, Li R, Pino S, Braverman LE. Effects of chronic iodine excess in a cohort of long-term American workers in West Africa. J Clin Endocrinol Metab. 2002 Dec;87(12):5499-502. PMID: 12466344 [PubMed - indexed for MEDLINE] http://jcem.endojournals.org/cgi/content/full/87/12/5499

Here are some figures for iodine in kombu/true kelp from the Web:

" For a reference point of the iodine content of sea veggies, a 1/4 ounce serving (equal to 7 grams) of dulse contains about 430 mcg. iodine, 1/4 ounce serving of nori contains 110 mcg., and a single gram of kelp contains up to 5,000 mcg of iodine!" http://www.goodfoods.coop/goodfoods042003.html

" Seaweed is best known for its high amounts of iodine, containing 62,000 mcg of iodine per hundred grams of seaweed, " http://www.healthrecipes.com/dulse_and_kelp.htm

"Two 6-inch strips of dried kelp (about 10 g) pack ... Iodine 1440 mcg" http://www.naturalhealthmag.com/flash/3?page=3

"Consumption of more than 100g/year (by dried weight) of most seaweeds carries a significant risk of thyroid disorder due to iodine intakes in excess of 1000 micrograms per day." http://www.purifymind.com/Iodine.htm

"Consumption of more than 100g/year (by dried weight) of most seaweeds carries a significant risk of thyroid disorder due to iodine intakes in excess of 1000 micrograms per day." http://www.vegansociety.com/html/food/nutrition/iodine.php

... which implies that kelp contains > 3650 mcg/g.

"Whole leaf kelp (Laminaria longicruris) has approximately 450 mcg. (micrograms or parts per million) iodine per gram. Our milled kelp (Laminaria digitata), sold in bulk and in our Sea Seasonings, has even higher amounts, about 5000 mcg. " http://www.seaveg.com/faq3.html

Kelp/Kombu, Whole Plant - Organic, 2 oz. "Certified Organic Kelp. Serving Size: 1/3 cup (7 g) Nutrient Amount %DV Iodine 2114%" http://www.organickingdom.com/co196.html

... which would mean just 453 mcg/g.

"a member of the Vegan Society's Council of Trustees ..., offers the following guide lines: Several sheets of nori seaweed could be eaten every day without any problems. By contrast, "because they are both so high in iodine, a half ounce of kombu or three and a half ounces of hijiki should last you about a year." http://www.findarticles.com/cf_dls/m1594/5_12/77749311/print.jhtml