LIVING NATURALLY with Olwen Anderson

"I'M SO tired” is a comment I often hear from women.

There's tiredness that's relieved by a good sleep.

Then there's a different kind of fatigue, that won't ease no matter how many hours you spend with your eyes closed.

Women seem particularly vulnerable to this kind of exhaustion thanks to our tendency to anaemia (iron deficiency) and hypo- thyroidism (underactive thyroid gland).

But one influences the other: did you know that anaemia can be what's behind your under- functioning thyroid?

Here's how each of them works: Your thyroid largely determines how much energy your cells will generate, but it's a complex process through producing thyroid prohormone T4, converting it to the active T3, and ensuring not too much reverse rT3 thyroid hormone is produced.

Then there's the input from your endocrine system supervisors, the hypothalamus and pituitary, which decide, based on feedback, how hard to push your thyroid gland to work.

Iron is the mineral we all need to enable blood cells to absorb and transport oxygen. But iron plays a big part in other body processes too, including thyroid hormone production. Scientists discovered this through a novel experiment I'm glad I didn't participate in. University students were recruited and lowered into a warm bath, which was then cooled down. The participants spent enough time in the cold water to watch a movie the scientists thoughtfully provided to keep them entertained.

Imagine spending your afternoon immersed in a cold bath, while researchers periodically check your temperature and draw blood. Ah, the things we'll do for science. Their study concluded being deficient in iron does affect your thyroid hormones. There's an iron-reliant enzyme that converts the prohormone T4 to the active thyroid hormone T3. Insufficient iron stores means the larger quantity of thyroid hormone needed when things get cold just isn't available because the raw materials aren't on hand to create it.

Curiously, it's the ferritin form of iron that impacts thyroid hormone production. There are two different types of iron in your body - serum iron, which is what's available for immediate use; and ferritin, which is stored iron which has to be converted to serum iron to be useful. A blood test reveals how much of each you have. So if you've got an underactive thyroid, it's advisable to check your iron levels as well.

Olwen Anderson is a naturopath and counsellor and a regular columnist with the Tweed Daily News. Visit www.olwenanderson.com.au