iThyroid.com

SMOKING

Smoking affects the thyroid through the production of many chemicals, but the overwhelming evidence is that the long-term effects of smoking on thyroidal function are due to cadmium toxicity. All green leafy plants including tobacco accumulate cadmium in the leaves and their consumption by eating or inhaling the smoke can greatly increase body levels of cadmium. The evidence is that cadmium suppresses thyroidal function. In Graves' Disease there is ample evidence to indicate that smoking increases the risk of both getting the disease and of getting ophthalmopathy (Thyroid Eye Disease).

Some people who quit smoking have had an increase in their hyper symptoms. My suspicion is that the cadmium in tobacco smoke suppresses thyroidal function in this way: cadmium is a direct antagonist to zinc which we know stimulates thyroidal production. Also cadmium uses up selenium which is essential for converting T4 to T3. I've always thought of smoking as an antidote to a high meat diet. There are extremely few vegetarian smokers. 

A high meat diet increases zinc intake and the cadmium from smoking competes with zinc and thereby prevents the stimulating effect that the zinc would have on the thyroid. In this way smoking relaxes the person by limiting the levels of thyroid hormone. Many people think that smoking is so addictive because of the nicotine. I think that what is overlooked is the drive to acquire cadmium to suppress zinc levels to prevent the jitters and stimulating effects of high thyroid hormone that zinc causes.

The cadmium from smoking also reduces copper which is needed to break down the thyroid hormones and thus get excess hormone out of the blood stream. So when you smoke, your thyroid production of T4 and conversion to T3 are suppressed, but you copper is suppressed also leading to a precarious balance of low hormone with low breakdown. Also as the cadmium builds up, the risk of Thyroid Eye Disease increases, along with an increased cancer growth rate because of the decreased selenium. While smoking is probably a compensation for over-stimulation from excessive zinc intake, it is not a good strategy for health.

Zinc should naturally be balanced by an increased intake of high copper foods. If more of the dietary intake of protein is in the form of nuts, seeds, and beans, then less zinc-containing meat will be consumed. Also the drive to smoke will be less, because of lower levels of zinc. One of the home remedies for quitting smoking is eating lots of sunflower seeds, which are a good source of copper to balance zinc.

Once you quit smoking, the problem is getting rid of the excess levels of cadmium. Cadmium is a heavy metal with a long half-life in the body. However, certain foods and supplements can help the body excrete cadmium and protect the body from the destructive effects of excess cadmium. Selenium and vitamin E work together to eliminate cadmium. Both copper and zinc compete with cadmium for transportation in the body, so they will also reduce cadmium levels. However, hypers should use copper rather than zinc to reduce cadmium because of zinc's stimulating effects on the thyroid. Hypos can use more zinc. Alpha lipoic acid is another supplement reported to help with cadmium removal.

Foods that are reported to help with cadmium detoxification are: chlorella, seaweed such as kelp, and cilantro. There are also some chelators such as EDTA, DMPA and BAL which are reported to remove cadmium from the body.

There is a tendency of people who quit smoking to increase their chocolate intake. Chocolate is another source of excessive cadmium, so this substitution is probably the result of the drive to get cadmium to balance zinc.

Other food sources of cadmium that should be restricted to lower cadmium levels are: all green leafy vegetables such as lettuce and spinach, carrots, liver and kidney, milled flour, rice, sugar, milk and other dairy products (contact with galvanized milk cans which contain cadmium), dried fruits (often dried on galvanized chicken wire, which contains zinc and cadmium), coffee, and tea.

Whenever you think about smoking, read the cadmium page. The evidence that cadmium from smoking and other sources is the largest single cause of thyroid disease is very convincing. 

Smoking Associated With Thyroid Disease

The following study shows that cadmium levels are about twice as high in the hair of smokers as in the hair of nonsmokers. Also higher are cobalt, arsenic, chromium, lead, and nickel. It makes you wonder if one of the reasons people smoke is to acquire their essential trace elements, but suffer because toxic elements are also ingested.

Sci Total Environ 1994 Dec 1;156(3):235-42

Heavy metals in human hair samples from Austria and Italy: influence of sex and smoking habits.

Wolfsperger M, Hauser G, Gossler W, Schlagenhaufen C

Institute of Nutrition, University of Veterinary Medicine, Vienna, Austria.

Hair samples from 79 young healthy adults from Vienna (Austria) and Rome (Italy) were analyzed for As, Cd, Co, Cr, Ni and Pb by ICP-MS. No differences were found between the two locations except for chromium, which was significantly higher in the Viennese population (P < 0.001). In both cities male hair contained higher arsenic (P < 0.001) and lower cadmium (P < 0.05) levels than female hair, and in Vienna lead concentrations were lower in males (P < 0.05). Striking differences appeared when smokers were compared with non-smokers. Geometric means (micrograms/g) of smokers versus non-smokers were: arsenic 0.081 vs. 0.065, cadmium 0.075 vs. 0.038 (P < 0.05), cobalt 0.025 vs. 0.010 (P < 0.05), chromium 0.84 vs. 0.72 (P < 0.05), lead 3.42 vs. 1.47 (P < 0.001) and nickel 0.64 vs. 0.32 (P < 0.005). Consideration of a large number of biological and behavioural factors minimizes bias inherent in unmatched sample composition.

Smoking And Menopause
Here's another reason for women to quit smoking: besides all the
other health problems it causes, smoking may trigger early
menopause.  A study published in the online version of Nature
Genetics finds that chemicals found in cigarette smoke may trip
the genetic signals that cause ovarian cells to die.  This
premature ovarian cell death may contribute to infertility in
women in their late thirties, according to a story in The Boston
Globe.  In the study, researchers from Massachusetts General
Hospital exposed mice to polycyclic aromatic hydrocarbons (PAHs),
which are found in cigarette smoke and other air pollutants, over
a six-year period.  The exposure triggered early menopause in the
mice, the Globe reports.  Then, the researchers grafted human
ovarian cells under the skin of the mice, and these cells too
died after exposure to the PAHs, the newspaper says.  The
researchers say that besides showing that cigarette smoking can
affect fertility, their study also suggests that menopause might
be delayed by blocking activation of the genetic signals that
shut down ovaries.