Testosterone and Iodine
I recently got the following question on the
Peak Testosterone Forum:
"OK, [I have not] done this but on [the cure zone] they have a group that has been painting iodine on there scrotum
- and they swear by it for libido and T levels. Now I have to say that there
is iodine information on that site along with links is very intriguing.
Supposedly 20mg a day (building up to it) is optimum and is close to what the Okinawa people consume.
Any thoughts on this?" 
I joked with the guy about this being a little tribal, but, in reality, it is
possible for iodine to help with both testosterone and libido a little and I'll
explain why below. But first, let's look at just what these men are
actually doing, i.e. their "protocol:" For example, one early senior-aged
man claimed massive improvements with his morning erections by doing the following:
Painted half his scrotum with 20 drops of iodine
The next night painted the other half with 20 drops of iodine
Take 15 mg Vitamin K (MK4)
Another guy on the same thread claimed to have increased his testosterone by 60% by taking 100 mg of iodine per day.
I'll cover dosing below, but this is a MASSIVE amount of iodine.
Now why would iodine increase testosterone? It turns out that the
well-known thyroid hormones, T3 and T4, contain iodine. In fact, T3
has three iodine molecules and T4 has four. And since some people are
actually low in iodine, i.e. have an iodine deficiency, this can lead to
hypothyroidism, since the thyroid gland lacks sufficient substrate. The
thyroid itself often enlargens as well, a condition called goiter. (Goiter
can also be caused by excess iodine, something we will discuss below.)
However, the interest in iodine comes from the fact that hypothyroid patients
have been found to have signficantly lower testosterone - perhaps by as much as
36%. And, what undoutedly caught the attention of the iodine fans, is that
fact that high dosages of T3 and T4 can bring testosterone back to a normal
level quite often. 
Somewhere along the way, someone got the idea that that taking a lot of iodine
would increase thyroid output and get rid of any hypothyroidism and, therefore,
increase testosterone. And, apparently, this actually works in some cases.
But is it safe?
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Potential Dangers of Excess Iodine
There are two primary concerns with consumption of excess iodine:
- Elevated TSH. Overconsumption of iodine has been shown to elevate TSH. Of course, TSH is the signaling hormone from the pituitary that
triggers the thyroid to release its hormones. A classic sign of hypothyroidism is
- Goiter. A goiter is basically an enlarged thyroid gland and is associated
with hypothyroidism, hyperthyroidism and in some cases probably thyroid cancer.
Now those taking extra iodine or painting the scrotum with iodine would argue
that they are not taking enough to trigger iodine-thyroid issues. This
idea would would seem debatable, because the RDA for iodine (in an adult male) is actually a very
small number: 150 mcg/day. Those using iodine are definitely
megadosing. And, what they seem to be ignoring, is the fact that a
number of studies show that TSH levels begin to rise at relatively low iodine levels
in the 1,700 mcg/day range. 
I am not trying to be insensitive toward someone trying to boost their
testosterone through what they see as a reasonable alternative, but I just do
not see the wisdom here. For example, let's take a hypogonadal male that has
total testosterone of 300 ng/dl who starts megadosing iodine. He might get
a boost up to 450 ng/dl. Now that increase is a nice increase, but it is
probably not going to make that much of a difference for him. And he is
risking hypothyroidism and goiter for this relatively small boost.
So why do iodine fans do it then? Well, there is some grey and
poorly understood areas of the research. In fact, the evidence seems to
point that some people can consume extra iodine and be affected less than one
might expect. In fact, there is even one study of northern Japanese
seaweed workeers, who consume a lot of seaweed - between 50 and 200 mg/day!  Of course, this is
about a 1,000 times the RDA and yet the prevalence of goiter is only about
6-12%. Of course, that is a high rate of goiter, but pro-iodine advocates like
out that hypothyroidism is not common there, a fact that has baffled the
Again, though, there is ample research that megadosing iodine can cause problems.
For example, a number of studies that show high iodine levels in the diet
can really causes problems. One study of Peace Corp
volunteers in Ghana found that 44% had goiter from excessive iodine in their
water filters. When this was taken care of, their "mean serum iodine
decreased from 293 ± 306 to 84 ± 46 μg/liter."  And, correspondingly, their
TSH dropped from a high 4.9 to a very sound 1.8 mU/liter.
So, to me it seems like risky business to consume extra iodine. One of the partipants in
the above-mentioned forum had her rheumatoid arthritis flare up when she took 15 mg per day.
It got worse from there:
"At about 20 mg per day, my throat starting closing in. I didn't know it at the
time but it was a goiter developing. At 30 mg per day, I experienced very scary
double vision, heart palpitations, light headedness, cold tingly numbness in my
head and nausea" 
Better safe than sorry...
Kenneth L Becker 2001, Principles and Pracice of Endocrinology and Metabolism,
4) The Journal of Clinical Endocrinology & Metabolism December 1, 2002 vol. 87
no. 12 5499-5502, "Effects of Chronic Iodine Excess in a Cohort of Long-Term
American Workers in West Africa"
7) Journal of Andrology, May-Jun 1988, 9(3):215-219, "Serum Levels of Total
Testosterone and Sex Hormone Binding Globulin in Hypothyroid Patients and Normal
Subjects Treated with Incremental Doses of L-T4 or L-T3"