Download HOW THE THYROID GLAND REGULATES METABOLISM

NEW BEGINNINGS Nutrition & Fitness
How Well Do You Know Your Thyroid?
DIET AND THYROID FUNCTION
There is a direct relationship between nutrition and hormones. The foods we eat
and the vitamins, minerals, and nutrients available to the body regulate the synthesis and
utilization of thyroid hormones. At the same time, thyroid hormones influence the rate of
metabolism of fuel sources from food: fats, proteins, and carbohydrates. Thyroid
hormones increase the rate of energy released from carbs, increase the rate of protein
synthesis, and stimulate the breakdown of fats. Low thyroid function slows the
metabolism of these foods, leading to depleted energy and a slower metabolic rate and
weight gain. In the presence of too much thyroid hormone, food is turned to energy with
high speed and efficiency, increasing the basal metabolic rate and leading to excessive
weight loss.
The digestive and endocrine systems are dependent upon each other for the
optimal absorption of nutrients from foods and the utilization of nutrients for hormone
synthesis. Hypothyroidism results in weight gain, despite a poor appetite, constipation,
pernicious anemia, poor utilization of fatty acids, and inadequate conversion of beta
carotene to vitamin A. Hypothyroidism is also associated with insufficient production of
hydrochloric acid by the parietal cells of the stomach. For those who don't know what
HCA does, it provides the proper pH environment for the digestion of proteins by the
enzyme pepsin. Without HCA, the amino acid phenylalanine cannot be obtained from
food, and tyrosine is unavailable in adequate amounts for the production of thyroxin (T4).
A cycle of hypothyroidism can be created in this interplay between digestion and thyroid
function. Hyperthyroidism can cause diarrhea, weight loss, and deficiencies in fat
soluble vitamins and calcium. Additionally, hyperthyroidism can increase metabolic rates
by as much as 200%, requiring an increased proportional intake of calories.
CONDITIONS ASSOCIATED WITH THYROID DYSFUNCTION
The thyroid gland, with the help of the pituitary, is the most important organ in
the body for controlling weight and body fat. Thyroid hormones define the rate of
cellular metabolism. If the thyroid gland is functioning properly, and enough thyroid
hormone is getting to the cells, the energy from food is properly utilized. If there is a
problem with the gland itself or if something is interfering with the thyroid hormone's
ability to bind to its target cells, metabolism alters, slowing down or speeding up every
process in the body, which in turn can cause many recurring problems.
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FATIGUE AND FREE-RADICAL DAMAGE
Fatigue can be directly related to problems with the thyroid. The process by
which energy from food is released and transferred to useable energy by the cells is a
complex chain of chemical reactions known as cellular respiration. Some energy is
released from food in the absence of oxygen (anaerobic respiration), but most is derived
in the mitochondria of the cells in the presence of oxygen (aerobic respiration). In the
mitochondria, aerobic respiration produces cellular energy in the form of ATP (a large
energy molecule). T3 and T4 are needed to utilize oxygen during aerobic respiration. If
T4 or T3 levels are low, cellular respiration and energy are depleted, excess oxygen
builds up in the cells, and oxidative, or free-radical, damage occurs. When these levels
are low, the number of mitochondria in our cells actually begins to decrease.
CARDIOVASCULAR DISEASE
The metabolism of fats and absorption of essential fatty acids (EFAs) are
important functions of the thyroid. Insufficient T4 to stimulate fat metabolism can lead
to Hyperlipidemia, or elevated cholesterol. Without the benefit of cardio protective
nutrients from essential fatty acids, you may be at an increased risk of cardiovascular
disease. If you have a high cholesterol reading, be sure to have your thyroid function
evaluated before beginning medication. T3 is necessary for the utilization of oxygen by
the mitochondria during cellular respiration. Inadequate T3 in the cells has a negative
effect on oxygen consumption. Excess oxygen results in an increase in the oxidation of
lipids (fats) and free radical damage. Increased oxidation of the low-density lipoprotein
(LDL) form of cholesterol, often referred to as "bad" cholesterol, has been identified in
hyperthyroidism and hypothyroid states.
INSULIN RESISTANCE
T4 also influences how quickly glucose (sugar) is absorbed from the intestines
and then taken up by the cells. T4 stimulates the conversion of proteins and fats to
glycogen when blood sugar is high and the transformation of glycogen to glucose when
blood sugar is low. The thyroid gland assists the pancreas and liver in maintaining stable
blood sugar. In other words, T4 increases insulin response.
STRESS AND THYROID FUNCTION
Chronic stress affects the thyroid and endocrine function in a number of ways.
The pituitary gland, the bodies "master gland," stimulates and controls the function of the
adrenal cortex by secreting adrenocorticotropic (ACTH). If required to maintain a
constant level of cortisol (the primary stress hormone), the pituitary gland may over
work. An overproduction of ACTH may divert the pituitary from manufacturing other
tropic hormones such as TSH, FSH, and LH.
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Cortisol production requires tyrosine, the same amino acid needed for the synthesis of
T4. Excess cortisol production can deplete tyrosine levels, prohibiting the thyroid gland
from producing thyroid hormones. Stress depletes other important nutrients for T4
production, namely chromium and zinc. Excessive cortisol production from chronic
stress also inhibits the conversion of T4 to T3 and the secretion of TSH.
HERE ARE SOME SYMPTOMS:
HYPOTHYROIDISM
behavior and mood...depression, fatigue, sleepiness, poor concentration
cardiovascular.........slow pulse rate (<70bpm)
cholesterol..............elevated cholesterol
features..................coarse voice, stunted growth, enlarged thyroid
Gastrointestinal........slowed digestion, bloating, heartburn, poor appetite
metabolism..............decreased basal metabolic rate, weight gain
muscles and reflexes. Muscle aches, cramping, numbness in hands and feet
respiratory...............breathing slows, poor ventilation
Tolerance to temp..... Intolerance to cold.
HYPERTHYROIDISM
behavior and mood...nervousness, irritability, insomnia, exhaustion
cardiovascular.........heart palpitations, rapid pulse
cholesterol..............decreased cholesterol
features.................bulging eyes, enlarged thyroid
gastrointestinal........diarrhea, increased appetite
metabolism..............increased basal metabolic rate, weight loss
muscles and reflexes. Muscle weakness, tremors
respiratory..............hyperventilation
tolerance to temp.....intolerance to heat.
HOW WELL DO YOU KNOW YOUR THYROID?
The BBT is a highly sensitive and accurate measure of low thyroid function,
perhaps exceeding the reliability of available blood tests. The late Broda Barnes, MD., a
pioneer in the diagnosis and treatment of thyroid disorders, developed this test and
successfully diagnosed and treated many patients from it.
The BBT test was developed as a simple measure of detecting hypothyroid conditions. It
is based on the observation that hypothyroid patients typically run lower than normal
body temperatures.
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This makes sense, since body temperature (heat output) is a direct measure of the amount
of fuel (food and oxygen) being burned by the cells.
In terms of the most accurate measurement of the thyroid function--that is, determining
the ability of thyroxin to enter the cells and influence metabolism--the BBT test is the
most logical assessment tool. The BBT should be taken immediately upon awakening.
To check your basal body temp, follow these simple steps:
1. Keep a thermometer by your bedside so you can take your temperature before getting
out of bed in the morning. (It is important to move as little as possible while taking your
temp.)
2. Shake down the thermometer to read less than 92.0 deg (unless you have a digital,
which I recommend.)
3. Upon awakening, take your auxiliary (armpit) temp for at least ten minutes.
4. Record your temp.
Repeat these steps for four days. (Menstruating women should record their temp
on the second, third, fourth, and fifth days of their periods.) Calculate your average temp
for four days. A normal metabolic rate will produce a waking temp of between 97.8 and
98.2 deg F. Temp below 97.8 may indicate, at the very least, subclinical hypothyroidism.
Temperatures higher than 98.6 may reflect hyperthyroidism.
HOW THE THYROID GLAND REGULATES METABOLISM
Within the endocrine system, the thyroid is the biological engine that ultimately
directs hormonal function and, therefore, metabolism. The thyroid gland produces the
hormones that make the body burn calories. Thyroid hormones are what drive your basal
metabolic rate (the energy required for internal or cellular work when the body is at rest),
or metabolism.
The thyroid is a large, butterfly-shaped gland with two lobes connected by a body
(or isthmus) over the trachea. Embedded within the thyroid gland are four masses of
tissue called the parathyroid glands. The thyroid produces and secretes three major
hormones: thyroxin, triiodothyronine, and calcitonin. Thyroid hormones influence
almost every cell of the body. The thyroid gland serves a crucial role in metabolism, fat
burning, and oxygen utilization, as well as in gastrointestinal and neuromuscular
function. That's why prolonged symptoms of heartburn or extended muscle aches are a
sign of low thyroid function.
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Just as importantly, T4 (define T4) increases the metabolic rate of almost every
tissue in the body. Its effects on metabolism are astonishing. For example, a person
whose thyroid gland reduces the production of T4 will experience as much as a 40% drop
in metabolism, or basal metabolic rate (the rate at which the body spends energy for
maintenance activities). Meanwhile, overproduction of T4 can increase normal metabolic
activity by 100%. T4 increases the basal metabolic rate (BMR) by impacting the rate of
ATP (energy) production in the mitochondria (the energy producing component of cells).
The thyroid uses much of this energy to convert caloric energy to heat in a process called
thermogenesis. In other words, how your body uses food determines your metabolism.
Thyroid hormone increases the utilization of carbohydrates and fat from food,
along with the rate of protein synthesis. It stimulates the appetite and the movement of
food through the digestive tract. In the presence of your thyroid hormone, muscle
catabolism increases, which increases the resting metabolic rate (muscle burns more
energy than fat). Thyroid hormone also increases the sensitivity of skeletal muscle to
impulses from the spinal cord. (An excess of thyroid hormone is known to cause tremors,
and a deficiency results in sluggish muscle response.) Thyroid hormone increases the
uptake of oxygen into the cells, which speeds aerobic respiration. Finally, thyroid
hormone actually increases the number of mitochondria within the cells.
As mentioned, the endocrine glands are in constant communication, not only with
each other, but also with the nervous and immune systems. In conjunction with the
pituitary gland, thyroid hormones influence almost every function in the body, as
metabolism establishes the official temperature at which systems operate. Because the
thyroid gland's work involves interaction with many body systems, it is particularly
sensitive to influences that can disrupt its proper functioning (this is key for those
supplementing with thyroid meds).
A FINAL NOTE ON THYROID FUNCTION
Many physicians now recognize the problems with thyroid regulation. In fact, the
window for acceptable TSH levels has just recently been changed by the American
Society of Endocrinologists to ensure that more people get diagnosed with
hypothyroidism and are provided with the help they need. Hopefully the use of T3 and
T4 as drug therapy will become more popular and, in addition, the various influencers of
thyroid metabolism such as stress and nutrient abnormalities will begin to become more
recognized in the coming decade. Healthy thyroid function is not only crucial for
improving one’s body composition, but just as important for graceful and vital aging.
Remember, the importance of your thyroid gland is critical, so please think before
treating it harmfully and taking thyroid meds. If you haven't already, take the basal body
temperature (BBT) test and see how your thyroid measures. Be responsible and your
body will thank you for it.
Copyright NEW BEGINNINGS NUTRITION & FITNESS®, 2005; All Rights Reserved