Thyroid for Dummies (33 page)

Thinking about food safety

Properly refrigerating foods that spoil quickly, such as meat, fish, and poultry, is essential. Keeping your fridge temperature below 5 degrees C (and freezer temperature below –18 degrees C) is ideal. Keep your hands clean when you handle these foods. And make sure that cutting boards and knives are cleaned well after you use them for cutting raw meats. Keep pets away from food preparation areas, and cover food to help keep flies at bay. The use of a mild bleach solution to cleanse cutting boards and kitchen surfaces is a good idea.

Always cook foods thoroughly. After you cook food, if you want to save it for a later time, keep it in the refrigerator. Leaving it at room temperature allows bacteria to grow and produces toxins that can cause food poisoning even if the food is thoroughly reheated to piping hot.

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Clarifying the Thyroid–Weight

Connection

Certain misconceptions exist about how your thyroid reacts to weight loss, and how your weight reacts to a change in your thyroid function. This section helps to dispel these misconceptions as it explains how your thyroid and your weight really interact.

Does my metabolism slow

when I lose weight?

People who lose weight on a diet often regain the weight after a time. You may have heard that the reason you can’t keep weight off is because your thyroid and metabolism slow down after you’ve lost some pounds, so weight comes back on more easily. This reasoning implies that your body establishes a ‘set point’ weight and tries to maintain it through changing your thyroid function and your metabolism whenever you move away from that weight.

The idea is that if you lose weight, your metabolic rate falls because your thyroid function declines. Researchers have studied this idea to determine its validity.

In a study in the
American Journal of Clinical Nutrition
, 2000, researchers tested thyroid function and metabolic rates for 24 overweight women in the process of losing weight. When actively losing weight, the women’s resting metabolic rates and free T3 hormone levels declined. But after reaching their normal weight, their free T3 levels and resting metabolic rate remained normal. This study contradicts the idea of a ‘set point’ weight.

If you are having trouble keeping off the weight you lose and your thyroid is functioning normally, this study shows that your thyroid is not to blame. You may want to take a closer look at your exercise and eating habits instead.

If I’m treated for hyperthyroidism,

am I doomed to gain weight?

Many people who are treated for hyperthyroidism with radioactive iodine complain that they cannot lose weight after they become hypothyroid and are placed on thyroid hormone replacement. If this describes your situation, you should consider a number of possible explanations: 21_031727 ch15.qxp 9/6/06 10:47 PM Page 188

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ߜ Perhaps you’re not taking enough thyroid hormones to replace your deficit. Importantly, check that your thyroid-stimulating hormone (TSH) is in the normal range, and ideally less than 2.5.

ߜ You may need to take T3 hormone replacement as well as T4, even if your TSH is normal (refer to Chapter 4), although this treatment is controversial in the United Kingdom.

ߜ Perhaps you’re eating foods that interfere with thyroid hormone absorption, such as soy protein, around the time you take the thyroid hormone tablet.

Then again, it’s possible that none of the above can explain your weight gain.

A study in the
Journal of the American College of Nutrition
in 1999, attempted to address this issue. The authors studied 10 people treated with radioactive iodine for hyperthyroidism. The researchers looked at the participants’ total food energy intake; their T4, T3, and TSH levels; and their height and weight at the time of treatment and at 1, 2, 3, 6, and 12 months afterwards.

The participants’ thyroid hormone levels declined in the first months of treatment but increased later. Even when thyroid hormone levels increased, the participants continued to gain weight.

Interestingly, the average weight of the participants before the development of hyperthyroidism was about 170 pounds; at the time of treatment, 148

pounds; and after a year, about 168 pounds. Their final average weight was actually lower than their average weight before hyperthyroidism developed.

The study concludes that weight gain after treatment of hyperthyroidism is initially due to a fall in the metabolic rate that accompanies the drop in thyroid hormone but later is due to food intake or lifestyle choices.

Another study, in the
Journal of Clinical Endocrinology and Metabolism
in 1998, showed where weight gain occurs in the body when hyperthyroidism is treated. Most of the weight gain in the first three months occurs as fat in the waist area and in muscle tissue, whereas weight gain later on is in the fat under the skin. This study shows very clearly that the weight loss occurring before treatment for hyperthyroidism is loss of lean tissue, the muscle mass.

(Therefore, further proof that using excess thyroid hormone for weight loss leads to loss of muscle.)

Many people treated for hyperthyroidism gain more weight than they want to after treatment. In most cases, this occurs either because their thyroid hormone levels are not in the ideal range, or because they do not alter their eating and exercise habits after treatment. If you’re in this situation, keep in mind that you probably increased your food intake and decreased your activity level when hyperthyroid. You need to make lifestyle adjustments after treatment in order to bring your body back to its healthy weight.

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The thyroid and coeliac condition

Coeliac condition is an autoimmune disease of

A study in the American Journal of Gastro-

the small intestine that results in poor absorp-

enterology in March 2001, found that out of 241

tion of fat, protein, carbohydrates, iron, and vit-

people with coeliac condition, 31 (13 per cent)

amins A, D, and K. The consequences of coeliac

also had hypothyroidism. Of the 31, 29 had sub-

condition are diarrhoea, osteomalacia (poorly

clinical hypothyroidism with an elevation in TSH

mineralised bone), signs of vitamin deficiency,

but a normal T4. After avoiding gluten in their

and anaemia. Studies show that as high as 21

diet for a year, the coeliac condition was cured,

per cent of people with coeliac condition also

and the thyroid abnormalities disappeared in all

have autoimmune hypothyroidism, and 3 per

of them as well.

cent of people with thyroid disease have coeliac

Thyroid disease is so commonly associated

condition.

with coeliac condition that everyone suffering

The treatment for coeliac condition is to remove

from it should have a thyroid function test. If

gluten from the diet. Gluten is found in wheat,

present, both the coeliac condition and the thy-

barley, and rye, and as a filler in many prepared

roid disorder may respond to gluten withdrawal.

foods and medications. When gluten is removed

from the diet, not only does coeliac condition dis-

appear, but the thyroid disease is cured as well.

Considering Iodine in Your Diet

Because iodine is a key element of thyroid hormones, iodine is a necessary part of your everyday diet (refer to Chapter 3). However, the consequences of not having enough iodine are dramatic and devastating to your health.

(Refer to Chapter 12 for the vastness of the problem in many countries and why this deficiency occurs.) This section shows you how to include iodine in your daily diet if you don’t eat animal products, and the occasions when you shouldn’t take too much of it.

Getting enough iodine in a vegetarian diet

Vegetarians, and especially vegans, do not eat key foods that contain iodine, such as fish, seafood, eggs, meat, and milk. You need to have sufficient iodine in your diet for good thyroid health. A study of vegetarians published in the
British Journal of Medicine
in December 1998, found that 63 per cent of the females and 36 per cent of the males had inadequate iodine intake.

If you follow a vegetarian diet, consider taking iodised salt or iodine supplements. A slice or two of bread also helps to take care of your iodine needs as a vegetarian.

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Avoiding iodine before thyroid studies

The results of thyroid uptake studies are more

ߜ Use only non-iodised salt

valuable if you avoid foods that contain iodine

ߜ Avoid milk and milk products

for a time before the test. The purpose of most

such studies is to determine the size and shape

ߜ Avoid commercial vitamin preparations

of your thyroid and whether or not a given

unless they definitely do not contain iodine

abnormality of the thyroid takes up iodine.

ߜ Steer clear of eggs

If you are having tests for hyperthyroidism, you

ߜ Don’t eat seafood, fish, shellfish, seaweed,

don’t need to avoid iodine. In fact, avoiding

and kelp

iodine may confuse the diagnosis because the

test is looking for abnormally high uptake of

ߜ Avoid cured and corned foods (for example,

iodine, and you do not want to artificially

ham, smoked fish, and tinned corned beef)

enhance the test results by following a low-

ߜ Don’t use bread products made with iodine

iodine diet.

dough conditioners

If you’re having a thyroid scan for reasons other

ߜ Avoid foods that contain Red Dye # 3, choco-

than hyperthyroidism, follow a low-iodine diet

late, molasses, and soy

for several days:

Exercising for Your Thyroid

If tests show that you have normal thyroid function, you can exercise as much as you want. Just ensure that you listen to your body and slow down if you feel you’re overextending yourself. The best form of activity is aerobic exercise, in which your heart is forced to beat faster, to keep your circulation healthy and your body fat under control. Also aim to do some strength training to retain and build muscle.

If tests show that your thyroid function is not yet within the normal range, you need to take special considerations regarding exercise, which are discussed in this section.

Recognising the natural

consequences of ageing

Don’t confuse the natural effects of ageing with the consequences of having thyroid disease. As you get older, your ability to do aerobic exercise is going to decrease, as is your strength. If you go to the gym for the first time in years 21_031727 ch15.qxp 9/6/06 10:47 PM Page 191

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and find you can’t last as long on the treadmill as you used to, chances are that your thyroid isn’t the culprit.

Your ability to take in oxygen is a measure of your physical condition. Your oxygen uptake peaks around the age of 25, and after that, it steadily declines no matter what you do to prevent it. Your strength also seems to peak around the same time, but it remains more or less the same until around age 40, when it starts to decline steadily. We lose about 25 per cent of our maximum strength by age 65. We also lose flexibility with ageing – our tendons, ligaments, and joint capsules become stiffer.

You have almost certainly heard the old saying, ‘You’re only young once.’

Unfortunately: It’s true.

At any age, exercise can maximise your strength, your stamina, and your flexibility, however. To achieve this benefit, aim for at least 30 minutes exercise, at least 5 times a week, and preferably every day.

Working out with hypothyroidism

When you have an underactive thyroid, your ability to exercise is limited by the fatigue that accompanies this condition. After you have begun taking the proper replacement dose of thyroid hormone, you can usually start to exercise normally. If you still can’t exercise because of fatigue, consider the two most common reasons:

ߜ Perhaps you’re not receiving sufficient thyroid hormone so your TSH is between 0.5 and 2.5 mU/ml (microunits per millilitre). If your symptoms linger even after taking the hormone replacement, don’t settle for a TSH

of 3 mU/ml or higher.

ߜ You may need to take T3 hormone in addition to T4 to fully replace your missing thyroid function (although this treatment is controversial in the United Kingdom).

Hypothyroidism does affect the functioning of your heart, which is often apparent during exercise. If you’re receiving treatment with thyroid hormone, your heart function should return to normal (assuming that you don’t have any other heart conditions).

Heart function during exercise is often a greater issue for people with subclinical hypothyroidism (where your TSH is elevated but your free T4 is normal), because this condition is often not treated with thyroid hormone. (Refer to Chapter 14 for a detailed discussion of the debate over treatment.) Subclinical hypothyroidism is associated with mild abnormalities in the heart, which are 21_031727 ch15.qxp 9/6/06 10:47 PM Page 192

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not measurable when you are resting but are detected when you exercise.

The normal ability of your heart to adapt to effort is diminished in subclinical hypothyroidism. Subclinical hypothyroidism also results in a rise in the form of cholesterol that leads to heart attacks and a fall in the form that is protective against heart attacks. Some thyroid specialists believe that these subtle changes are reason enough to treat subclinical hypothyroidism with thyroid hormone.