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Dr. Peat's thoughts about Thyroid Disease

Updated: Mar 31, 2023

An Interview With Dr. Raymond Peat who offers his thoughts about Thyroid Disease


Mary Shomon: Why do women with treated hypothyroidism frequently still have inappropriately high levels of cholesterol and high triglycerides, and what can they do to help lower these levels?

Dr. Ray Peat: Often it’s because they were given thyroxine, instead of the active thyroid hormone, but hypertriglyceridemia can be caused by a variety of things that interact with hypothyroidism. Estrogen treatment is a common cause of high triglycerides, and deficiencies of magnesium, copper, and protein can contribute to that abnormality. Toxins, including some drugs and herbs, can irritate or stimulate the liver to produce too much triglyceride. T3, triiodothyronine, is the active thyroid hormone, and it is produced (mainly in the liver) from thyroxine, and the female liver is less efficient than the male liver in producing it, as is the female thyroid gland.

The thyroid gland, which normally produces some T3, will decrease its production in the presence of increased thyroxine. Therefore, thyroxine often acts as a “thyroid anti-hormone,” especially in women. When thyroxine was tested in healthy young male medical students, it seemed to function “just like the thyroid hormone,” but in people who are seriously hypothyroid, it can suppress their oxidative metabolism even more. It’s a very common, but very serious, mistake to call thyroxine “the thyroid hormone.”

High cholesterol is more closely connected to hypothyroidism than hypertriglyceridemia is. Increased T3 will immediately increase the conversion of cholesterol to progesterone and bile acids. When people have abnormally low cholesterol, I think it’s important to increase their cholesterol before taking thyroid, since their steroid-forming tissues won’t be able to respond properly to thyroid without adequate cholesterol.

Mary Shomon: You feel that progesterone can have anti-stress effects, without harming the adrenal glands. Is progesterone therapy something you feel is useful to many or most hypothyroid patients? How can a patient know if she needs progesterone? Do you recommend blood tests? And if so, at what point in a woman’s cycle?

Dr. Ray Peat: Estrogen blocks the release of hormone from the thyroid gland, and progesterone facilitates the release. Estrogen excess or progesterone deficiency tends to cause enlargement of the thyroid gland, in association with a hypothyroid state. Estrogen can activate the adrenals to produce cortisol, leading to various harmful effects, including brain aging and bone loss. Progesterone stimulates the adrenals and the ovaries to produce more progesterone, but since progesterone protects against the catabolic effects of cortisol, its effects are the opposite of estrogen’s. Progesterone has antiinflammatory and protective effects, similar to cortisol, but it doesn’t have the harmful effects. In hypothyroidism, there is a tendency to have too much estrogen and cortisol, and too little progesterone.

The blood tests can be useful to demonstrate to physicians what the problem is, but I don’t think they are necessary. There is evidence that having 50 or 100 times as much progesterone as estrogen is desirable, but I don’t advocate “progesterone replacement therapy” in the way it’s often understood. Progesterone can instantly activate the thyroid and the ovaries, so it shouldn’t be necessary to keep using it month after month. If progesterone is used consistently, it can postpone menopause for many years.

Cholesterol is converted to pregnenolone and progesterone by the ovaries, the adrenals, and the brain, if there is enough thyroid hormone and vitamin A, and if there are no interfering factors, such as too much carotene or unsaturated fatty acids. Progesterone deficiency is an indicator that something is wrong, and using a supplement of progesterone without investigating the nature of the problem isn’t a good approach. The normal time to use a progesterone supplement is during the “latter half” of the cycle, the two weeks from ovulation until menstruation. If it is being used to treat epilepsy, cancer, emphysema, migraine or arthritis, or something else so serious that menstrual regularity isn’t a concern, then it can be used at any time. If progesterone is used consistently, it can postpone menopause for many years.

Mary Shomon: What supplements do you feel are essential for most people with hypothyroidism? Dr. Ray Peat: Because the quality of commercial nutritional supplements is dangerously low, the only supplement I generally advocate is vitamin E, and that should be used sparingly. Occasionally, I will suggest limited use of other supplements, but it is far safer in general to use real foods, and to exclude foods which are poor in nutrients. Magnesium is typically deficient in hypothyroidism, and the safest way to get it is by using orange juice and meats, and by using epsom salts baths; magnesium carbonate can be helpful, if the person doesn’t experience side effects such as headaches or hemorrhoids.

Mary Shomon: Do you feel that there are any special considerations, issues, or treatments for men with hypothyroidism?

Dr. Ray Peat: Thyroid supplements can be useful for prostate hypertrophy and some cases of impotence and infertility. Occasionally, a man who can’t put on a normal amount of weight finds that a thyroid supplement allows normal weight gain. Leg cramps, insomnia and depression are often the result of hypothyroidism. Heart failure, gynecomastia, liver disease, baldness and dozens of other problems can result from hypothyroidism.

Mary Shomon: Many people describe how they are clinically hypothyroid, with elevated TSH levels, but have extremely high pulse rates. Do you have any thoughts as to what might be going on in that situation?

Dr. Ray Peat: In hypothyroidism, thyrotropin-release hormone (TRH) is usually increased, increasing release of TSH. TRH itself can cause tachycardia, “palpitations,” high blood pressure, stasis of the intestine, increas of pressure in the eye, and hyperventilation with alkalosis. It can increase the release of norepinephrine, but in itself it acts very much like adrenalin. TRH stimulates prolactin release, and this can interfere with progesterone synthesis, which in itself affects heart function.

I consider even the lowest TSH within the “normal range” to be consistent with hypothyroidism; in good health, very little TSH is needed. When the thyroid function is low, the body often compensates by over-producing adrenalin. The daily production of adrenalin is sometimes 30 or 40 times higher than normal in hypothyroidism. The adrenalin tends to sustain blood sugar in spite of the metabolic inefficiency of hypothyroidism, and it can help to maintain core body temperature by causing vasoconstriction in the skin, but it also disturbs the sleep and accelerates the heart.

During the night, cycles of rising adrenalin can cause nightmares, wakefulness, worry, and a pounding heart. Occasionally, a person who has chronically had a heart rate of 150 beats per minute or higher, will have a much lower heart rate after using a thyroid supplement for a few days. If your temperature or heart rate is lower after breakfast than before, it’s likely that they were raised as a result of the nocturnal increase of adrenalin and cortisol caused by hypothyroidism.

Mary Shomon: You have written that for some people, there is a problem converting T4 to T3, but that diet can help. You recommend a piece of fruit or juice or milk between meals, plus adequate protein, can help the liver produce the hormone. Can you explain a bit more about this idea and how it works?

Dr. Ray Peat: The amount of glucose in liver cells regulates the enzyme that converts T4 to T3. This means that hypoglycemia or diabetes (in which glucose doesn’t enter cells efficiently) will cause hypothyroidism, when T4 can’t be converted into T3. When a person is fasting, at first the liver’s glycogen stores will provide glucose to maintain T3 production. When the glycogen is depleted, the body resorts to the dissolution of tissue to provide energy. The mobilized fatty acids interfere with the use of glucose, and certain amino acids suppress the thyroid gland. Eating carbohydrate (especially fruits) can allow the liver to resume its production of T3.

Mary Shomon: You have recommended if supplemental T3 is used, a thyroid patients “nibble on a 10-15 mg Cytomel tablet throughout the day.” Can you explain why? Would compounded time-released T3 as available in some compounding pharmacies do the same? Dr. Ray Peat: Most hypothyroid people can successfully use a supplement that contains four parts of thyroxine for each part of T3, but some people need a larger proportion of T3 for best functioning. The body normally produces several micrograms of T3 every hour, but if a large amount of supplementary thyroid is taken in a short time, the liver quickly inactivates some of the excess T3. Taking a few micrograms per hour provides what the body can use, and doesn’t suppress either the liver’s or the thyroid’s production of the hormone.

I have only rarely talked to anyone who had good results with the so-called time-release T3, and I have seen analyses of some samples in which there was little or no T3 present. It is hard to compound T3 properly, and the conditions of each person’s digestive system can determine whether the T3 is released all at once, or not at all. I don’t think there is a valid scientific basis for calling anything “time-release T3.”

I have been told that the company which now owns the Armour name and manufactures “Armour thyroid USP” has added a polymer to the formula, and I think this would account for the stories I have heard about its apparent inactivity. Some people have found that the tablets passed through their intestine undigested, so I think it’s advisable to crush or powder the tablets.

Mary Shomon: You feel that excessive aerobic exercise can be a cause of hypothyroidism. Can you explain this further? How much is too much? Dr. Ray Peat: I’m not sure who introduced the term “aerobic” to describe the state of anaerobic metabolism that develops during stressful exercise, but it has had many harmful repercussions. In experiments, T3 production is stopped very quickly by even “sub-aerobic” exercise, probably becaue of the combination of a decrease of blood glucose and an increase in free fatty acids. In a healthy person, rest will tend to restore the normal level of T3, but there is evidence that even very good athletes remain in a hypothyroid state even at rest. A chronic increase of lactic acid and cortisol indicates that something is wrong. The “slender muscles” of endurance runners are signs of a catabolic state, that has been demonstrated even in the heart muscle. A slow heart beat very strongly suggests hypothyroidism. Hypothyroid people, who are likely to produce lactic acid even at rest, are especially susceptible to the harmful effects of “aerobic” exercise. The good effect some people feel from exercise is probably the result of raising the body temperature; a warm bath will do the same for people with low body temperature.

Mary Shomon: You feel that chronic protein deficiency is a common cause of hypothyroidism. How much protein should people get (as much as 70-100 grams a day?) and what types of protein, in order to prevent hypothyroidism? Dr. Ray Peat: The World Health Organization standard was revised upward by researchers at MIT, and recently the MIT standard has been revised upward again by military researchers; this is described in a publication of the National Academy of Sciences (National Academy Press, The Role of Protein and Amino Acids in Sustaining and Enhancing Performance, 1999). When to little protein, or the wrong kind of protein, is eaten, there is a stress reaction, with thyroid suppression. Many of the people who don’t respond to a thyroid supplement are simply not eating enough good protein. I have talked to many supposedly well educated people who are getting only 15 or 20 grams of protein per day.

To survive on that amount, their metabolic rate becomes extremely low. The quality of most vegetable protein (especially beans and nuts) is so low that it hardly functions as protein. Muscle meats (including the muscles of poultry and fish) contain large amounts of the amino acids that suppress the thyroid, and shouldn’t be the only source of protein. It’s a good idea to have a quart of milk (about 32 grams of protein) every day, besides a variety of other high quality proteins, including cheeses, eggs, shellfish, and potatoes. The protein of potatoes is extremely high quality, and the quantity, in terms of a percentage, is similar to that of milk.

Mary Shomon: You talk about darkness and shorter days of winter as a stress. It’s known that more thyroid hormone is needed by some patients during colder weather. Are there other things you recommend patients do to “winterproof” their metabolism?

Dr. Ray Peat: Very bright incandescent lights are helpful, because light acts on, and restores, the same mitochondrial enzymes that are governed by the thyroid hormone. In squirrels, hibernation is brought on by the accumulation of unsaturated fats in the tissues, suppressing respiration and stimulating increased serotonin production. In humans, winter sickness is intensified by those same antithyroid substances, so it’s important to limit consumption of unsaturated fats and tryptophan (which is the source of serotonin). When a person is using a thyroid supplement, it’s common to need four times as much in December as in July.

Mary Shomon: You have reported that pregnenolone can be helpful for Graves’ patients with exophthalmus. Can you explain further?

Dr. Ray Peat: Graves’ disease and exophthalmos can occur with hypothyroidism or euthyroidism, as well as with hyperthyroidism. Pregnenolone regulates brain chemistry in a way that prevents excessive production of ACTH and cortisol, and it helps to stabilize mitochondrial metabolism. It apparently acts directly on a variety of tissues to reduce their retention of water. In the last several years, all of the people I have seen who had been diagnosed as “hyperthyroid” have actually been hypothyroid, and benefitted from increasing their thyroid function; some of these people had also been told that they had Graves’ disease.

Mary Shomon: You are a proponent of coconut oil for thyroid patients. Can you explain why?

Dr. Ray Peat: An important function of coconut oil is that it supports mitochondrial respiration, increasing energy production that has been blocked by the unsaturated fatty acids. Since the polyunsaturated fatty acids inhibit thyroid function at many levels, coconut oil can promote thyroid function simply by reducing those toxic effects. It allows normal mitochondrial oxidative metabolism, without producing the toxic lipid peroxidation that is promoted by unsaturated fats.

Mary Shomon: Do you have any thoughts for thyroid patients who are trying to do everything right, and yet still can’t lose any weight? Dr. Ray Peat: Coconut oil added to the diet can increase the metabolic rate. Small frequent feedings, each combining some carbohydrate and some protein, such as fruit and cheese, often help to keep the metabolic rate higher. Eating raw carrots can prevent the absorption of estrogen from the intestine, allowing the liver to more effectively regulate metabolism. If a person doesn’t lose excess weight on a moderately low calorie diet with adequate protein, it’s clear that the metabolic rate is low. The number of calories burned is a good indicator of the metabolic rate. The amount of water lost by evaporation is another rough indicator: For each liter of water evaporated, about 1000 calories are burned.

Mary Shomon:You have talked about internal malnutrition as a problem for many thyroid patients, due to insufficient digestive juices and poor intestinal movements. Are there ways patients who are treated for hypothyroidism can help alleviate this problem.

Dr. Ray Peat: The absorption and retention of magnesium, sodium, and copper, and the synthesis of proteins, are usually poor in hypothyroidism. Salt craving is common in hypothyroidism, and eating additional sodium tends to raise the body temperature, and by decreasing the production of aldosterone, it helps to minimize the loss of magnesium, which in turn allows cells to respond better to the thyroid hormone. This is probably why a low sodium diet increases adrenalin production, and why eating enough sodium lowers adrenalin and improves sleep. The lowered adrenalin is also likely to improve intestinal motility.

Mary Shomon: You’ve mentioned eggs, milk and gelatin as good for the thyroid. Can you explain a bit more about this? Dr. Ray Peat: Milk contains a small amount of thyroid and progesterone, but it also contains a good balance of amino acids. For adults, the amino acid balance of cheese might be even better, since the whey portion of milk contains more tryptophan than the curd, and tryptophan excess is significantly antagonistic to thyroid function. The muscle meats contain so much tryptophan and cysteine (which is both antithyroid and potentially excitotoxic) that a pure meat diet can cause hypothyroidism. In poor countries, people have generally eaten all parts of the animal, rather than just the muscles==feet, heads, skin, etc.

About half of the protein in an animal is collagen (gelatin), and collagen is deficient in tryptophan and cysteine. This means that, in the whole animal, the amino acid balance is similar to the adult’s requirements. Research in the amino acid requirements of adults has been very inadequate, since it has been largely directed toward finding methods to produce farm animals with a minimum of expense for feed. The meat industry isn’t interested in finding a diet for keeping chickens, pigs, and cattle healthy into old age.

As a result, adult rats have provided most of our direct information about the protein requirements of adults, and since rats keep growing for most of their life, their amino acid requirements are unlikely to be the same as ours.

Mary Shomon: Do you think the majority of people with hypothyroidism get too much or too little iodine? Should people with hypothyroidism add more iodine, like kelp, seaweeds, etc.?

Dr. Ray Peat: 30 years ago, it was found that people in the US were getting about ten times more iodine than they needed. In the mountains of Mexico and in the Andes, and in a few other remote places, iodine deficiency still exists. Kelp and other sources of excess iodine can suppress the thyroid, so they definitely shouldn’t be used to treat hypothyroidism.

Mary Shomon: What are your thoughts for Graves’ disease/hyperthyroidism patients? Should they move ahead quickly to get radioactive iodine treatment, or are there natural things they might be able to try to temporarily or even permanently get a remission? Dr. Ray Peat: Occasionally, a person with a goiter will temporarily become hyperthyroid as the gland releases its colloid stores in a corrective process. Some people enjoy the period of moderate hyperthyroidism, but if they find it uncomfortable or inconvenient, they can usually control it just by eating plenty of liver, and maybe some cole slaw or raw cabbage juice. Propranolol will slow a rapid heart. The effects of a thyroid inhibitor, PTU, propylthiouracil, have been compared to those of thyroidectomy and radioactive iodine. The results of the chemical treatment are better for the patient, but not nearly so profitable for the physician.

Besides a few people who were experiencing the unloading of a goiter, and one man from the mountains of Mexico who became hypermetabolic when he moved to Japan (probably from the sudden increase of iodine in his diet, and maybe from a smaller amount of meat in his diet), all of the people I have seen in recent decades who were called “hyperthyroid” were not. None of the people I have talked to after they had radioiodine treatment were properly studied to determine the nature of their condition. Radioiodine is a foolish medical toy, as far as I can see, and is never a proper treatment.

raymond peat thyroid health illness


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