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The Thyroid Gland: Metabolic Power Throttle


"Although extremely common, low thyroid is largely an unsuspected illness. Even when suspected, it is frequently undiagnosed. When it is diagnosed, it often goes untreated. When it is treated, it is seldom treated optimally".

THYROID POWER: 10 Steps to Total Health
Richard Shames, M.D. (2001)

Shaped like a butterfly, the thyroid gland consists of two lobes that lie on each side of the trachea located just below the Adam's apple. It's one of the largest endocrine glands in the body and is also one of the most sensitive. This unique mass of specialized tissue produces the thyroid hormones thyroxine (T4) and triiodothyronine (T3), the primary regulators of human metabolism. The numbers 4 & 3 after the "T" designate the number of iodine atoms they each contain. Both hormones are classified as Biogenic Amines and are derived from the amino acid tyrosine.

Thyroid hormones accelerate cellular reactions and increase oxidative metabolism. By stimulating enzymes that control active transport pumps, demand for cellular oxygen increases, and as ATP production goes up, heat is produced. This creates a thermoregulatory effect, which increases body temperature. Basal metabolic rate (BMR) is directly influenced by thyroid hormone chemistry. Thyroid hormones can target, influence and alter the metabolism of virtually every cell in the body. They affect mood, bodyweight, stamina and even fertility.

Thyroid hormones stimulate protein synthesis and increase the rate at which triglycerides are broken down (lipolysis). This is why they are used by some athletes in sports where the appearance of the physique is judged, especially during the final stages of pre-contest dieting. Basically, they help preserve muscle and reduce body fat, but when used incorrectly and/or excessively, they are highly catabolic to muscle.

Synthetic forms of pure thyroxine (Synthroid, Levothroid, Levoxyl) rate high on the list of drugs most frequently prescribed by physicians. They can stimulate appetite, speed metabolic rate and help people lose weight, but if abused or used incorrectly, they can also cause serious heart problems, muscle weakness and muscle wasting. Alternatives to T4 alone include synthetic T3 (Cytomel) and desiccated animal gland extracts that contain both T4 & T3 (Armour, Naturthroid, Westroid). All forms may be useful depending on the individual and thyroid condition; the trick is to determine the best dose, form and combination.

The thyroid secretes about ten times as much T4 as T3; however, T3 is roughly 2-3 times more potent. Thyroxine is converted into the more active triiodothyronine with the selenium dependent enzyme 5'-deiodinase. Thus, some thyroid disorders are simply a consequence of consuming a diet that lacks sufficient selenium. T3 and T4 are lipid-soluble and combine with special transport proteins upon release into the serum, called thyroxine-binding globulins (TBG). Less than 1% of thyroid hormones travel unattached in their free state.

During growth, thyroid hormones provide an anabolic influence on protein metabolism. This is due to their influence on insulin secretion. T4 and insulin also connect in the liver, where they mutually affect IGF activity. IGF (Insulin Growth Factors) are powerful muscle building control agents. In the absence of adequate levels of thyroid hormones, human growth hormone (hGH) also loses its growth-promoting action and is not secreted normally.

Iron Influences Thyroid Function

Anemia induced through iron deficiency has been shown to significantly reduce circulating levels of T4-5'deiodinase in rats, resulting in suppression of the conversion of T4 to T3. Beard et al. also showed a connection between iron deficiency anemia and low plasma T4 levels in human subjects. After 12 weeks of iron supplementation, the iron deficiency was corrected, and both T4 levels and the subjects' ability to thermoregulate their body temperature following exposure to cold improved. (Beard, J.L. Impaired thermoregulation and thyroid function in iron-deficiency anemia. Am. J. Clin. Nutr. 52:813-819, 1990).

Who Has Problems With Thyroid Health?

Thyroid problems are incredibly common in North America, especially among women. As a RULE, when all else fails and you can't figure out what's wrong, suspect low thyroid and get it tested ASAP. Many experts believe this epidemic is caused by excess chemicals in our food, air and water, all of which stress the immune system leading to a high incidence of autoimmune illness. Common symptoms of low thyroid include unusual fatigue, susceptibility to feeling cold, trouble with weight management, prominent bags under eyes, muscle and joint aches and pains, problems with digestion, mental sluggishness, dry skin, depression, migraines and waking up feeling tired.

Instead of feeling refreshed after a morning workout, you might feel like going back to bed (even though it's only 10am). Or, after work instead of heading to the gym, you head straight home because you feel completely drained. Athletes with low thyroid do not perform well when the ambient temperature drops below 50º F. The synovial fluid in the joints also tends to "thicken", thus reducing joint motility and increasing risk of injury.

Women typically under consume protein, especially low-fat, non-denatured animal protein, which provides a strong source of the essential amino acid phenylalanine. Tyrosine is known as the "anti-stress" amino, and is greatly depleted after hard workouts and exhausting sport competition. Thyroid hormones depend on ample pools of tyrosine, which is dependent on phenylalanine intake. Fortunately, tyrosine can be taken directly in supplement form.

The Thyroid Basal Temperature Test

Body temperature is a useful sign for measuring metabolic rate, and according to Dr. Broda Barnes, author of Hypothyroidism: The Unsuspected Illness, "More information can be brought to the physician with only the aid of an ordinary thermometer, than can be attained with all other thyroid function tests combined".

Before retiring in the evening, place a mercury basal thermometer on your bedside table. As soon as you wake-up, place the thermometer in the centre of your armpit and then lay still for about 10 minutes. Record your body temperature and repeat this procedure for 3 consecutive days. Women should do this test during the first few days after menstruation begins.

Add the three temperatures together and divide by 3. This figure represents your average basal metabolic temperature, which is reflective of thyroid hormone output. A normal temperature is approximately 37° C (98° F). Although "normal" does vary from person to person, a reading 1° or more below this range could indicate a problem with your thyroid.

What Dietary Supplements Are Useful?

Tyrosine, EFAs, Whey Protein Isolate, Selenium, Iron, Thyroid Glandular (desiccated thyroid with active ingredients removed), Glutamine & Lipoic Acid are specific to the problem at hand. Protein shakes are advised both before and after exercise. This is also a good time to add 1-2 tsp. of The Sport Oil, which helps ensure a reliable source of alpha-linolenic acid (omega-3). EFAs and whey protein isolate make a perfect pair to support nourishment of the entire endocrine gland system.

Recommended Self-Help Steps

1. Read THYROID POWER: 10 Steps to Total Health
2. Measure your Basal Body Temperature
3. Seek out an understanding health practitioner
4. Suggested Panel of Thyroid Tests

o TSH
o Basal Temperature Test
o T4 Panel (Total T4, T3 Uptake, Free Thyroxine Index)
o T3 Total
o Antiperoxidase (microsomal) antibody

5. Avoid trans-fats (hydrogenated vegetable oils, fried foods), salt, sugar, peanuts, soy, raw cruciferous vegetables
6. Eat fresh organic whole food and high quality proteins
7. Move to Hawaii (hang loose Brah!)