The single biggest hurdle I had to leap through to begin my carnivorous adventure was the fear of "low-carb induced hypothyroidism". When I began to explore research on the subject, I hit a brick wall of alarmist forum posts and erroneous pub-med articles of varied importance. But the consensus was clear, you must consume dietary carbohydrates to keep your thyroid healthy.

Over the years I learned to listen to my body and it was clearly telling me to restrict carbohydrates. I finally gave in, managed to ignore the fear mongering of conventional wisdom and dropped carbohydrates completely.

The question however is still valid.

Does a carnivorous diet positively or negatively affect the thyroid gland?

There isn't much data pertaining to the thyroid health of subjects who ate close to or a completely carnivorous diet, so I'll be dipping into ketogenic diet and fasting research. The difference being that a ketogenic diet consists of about ~50g of carbohydrates a day with the remaining calories coming from fat and protein. From here on out I will use the terms "carnivorous diet" and "ketogenic diet" interchangeably since in all likelihood they aren't much different.

First lets explore the reasons why we want a healthy thyroid. Here is a quick overview of the functions this butterfly shaped gland performs.

• Metabolic Rate - When people say "metabolism", they might as well be saying "thyroid". Within the endocrine system, the thyroid along with the adrenal glands are the biological engines that ultimately direct our hormonal metabolism.
• Setting Proteins - The thyroid can increase and decrease the rate of protein degradation.
• Creation of Thyroxine (T4) - The thyroid produces a couple of different hormones, the most important being T4 and…
• Creation of Triiodothyronine (T3) - T3 is the metabolically active version of T4. T3 is responsible for the thyroids metabolic influencing affects while thyroxine (T4) is considered to be a storage form of T3 waiting to be converted into T3 by the liver.

A carnivorous diet is very similar to the metabolic state the body is in when fasting. Without discussing too much of the technical jargon, a carnivorous diet will lower blood sugar, lower basal insulin, decrease inflammation, balance hormones, reduce oxidative stress and support the immune system. Fasting is the only other method that can match the incredible health promoting effects of a dietary decrease in carbohydrate consumption. The downside to fasting being that you have to eat sometime!

So what happens happens to our thyroid when we fast?

In short, it slows down. And it especially slows down when you decrease calories in tandem.

So what gives? Isn't the slow down of the thyroid what we're trying to avoid?

This is were the forum posting alarmists get it wrong. Fortunately the decline of serum T3 due to fasting is not associated with the disease state known as hypothyroidism. 

"Despite the fall in T3 levels, clinical hypothyroidism does not develop. Thyrotropin values do not rise, as might be expected in primary thyroid dysfunction: in fact basal TSH concentrations may decrease in short-term fasting or remain unchanged in prolonged (more than three weeks) fasting. In addition, TSH response to thyrotropin releasing hormone infusions may be blunted or unchanged."

While I'm not always a fan of his work, Lyle McDonald wrote a fantastic book on ketosis. Lyle's research echoes the study above demonstrating that while low-carb diets induce lower numbers of the thyroid hormone T3, it is not related to the disease condition known as hypothyroidism.

Hypothyroidism and euthyroid stress syndrome (ESS) There are two common syndromes associated with low levels of T3 which need to be differentiated from one another. Hypothyroidism is a disease characterized by higher than normal thyroid stimulating hormone (TSH) and lower levels of T3 and T4. The symptoms of this disease include fatigue and a low metabolic rate.

The decrease in T3 due to hypothyroidism must be contrasted to the decrease seen during dieting or carbohydrate restriction. Low levels of T3 with normal levels of T4 and TSH (as seen in ketogenic dieting) is known clinically as euthyroid stress syndrome (ESS) and is not associated with the metabolic derangements seen in hypothyroidism (1). The drop in T3 does not appear to be linked to a drop in metabolic rate during a ketogenic diet (17,52).

As with other hormones in the body (for example insulin), the decrease in circulating T3 levels may be compensated for by an increase in receptor activity and/or number (1). This has been shown to occur in mononuclear blood cells but has not been studied in human muscle or fat cells (53). So while T3 does go down on a ketogenic diet, this does not appear to be the reason for a decrease in metabolic rate.

Lyle McDonald (1998) The Ketogenic Diet: A Complete Guide for the Dieter and Practitioner (pp. 48)

The decrease in T3 during fasting is the body adapting to its metabolic condition in order to preserve muscle mass and conserve energy. Remember, the thyroid is also responsible for rate of protein catabolism. The body being as smart as it is, down regulates the thyroid to conserve fuel and protect lean mass. 

There is no better example than the steroid abusing muscle heads on the bodybuilding forums I used to frequent. Those who aggressively used Cytomel (prescription T3) for weight loss during a "cut" had less than stellar experiences. I remember vivid accounts from unhappy forum members who used Cytomel for too long and wasted away, due to excessive T3.

The Autoimmune Connection

The most common type of thyroid dysregulation is known as Hashimoto's thyroiditis. This disorder is characterized by the body becoming allergic to thyroid hormones. The body produces antibodies that begin to attack its own thyroid tissue. While little is known about the specific origins of Hashimoto's we can confidently say that ridding the diet of grains (gluten specifically) is of paramount importance. 

Gluten is a pro-inflammatory protein found in "heart healthy" whole grains as well as most processed foods. The autoimmune disease, celiac disease, is characterized by eating these foods. Can we stop a second? A disease that increases cancer, osteoporosis, thyroid disease, multiple sclerosis, rheumatoid arthritis, and neurodegenerative states is caused by eating a food that our government tells us to eat 6-11 servings of. Shocking.

Besides avoiding grains, which is done naturally on a carnivorous regime, getting adequate Vitamin D is becoming more and more important. Carnivorous subscribers don't have a bulletproof vest for this one. I don't like recommending supplements, but like Dr. Harris of the PaNu Weblog says:

"Vitamin D is replacement, not supplementation. We are trying to get our 25(OH)D levels up to paleolithic normal which will be above the Neolithic normal."

For an overview, let's head over to Animal Pharm run by the exuberant Dr. BG. If you haven't already subscribed, she is a hoot and you should immediately. 

"How to Stop the Autoimmune Process of Hashimoto's

When one of our organs is jacked how do we recover it? Can we induce our immune system to heal and restore function? Certainly! With time, appropriate nutrients and stimulus, I believe depending on the extent of the incurred damage, our bodies have the capacity to regenerate itself. With Vitamin D repletion and Wheat-Cessation, I have observed a trend of improved TSH (including my own from 1.3-1.9 to 1.0 when my 25(OH)D stays above 60 ng/ml). Why? Vitamin D interacts intimately with thyroid, vitamin A/carenoid and other steroid hormone controls, including the sex hormones.

• These below nutrients and lifestyle changes have been shown to aid the Thyroid to heal and restore functionality:
• stopping wheat which triggers our immune systems: innate+humoral
• stopping wheat which triggers genetic expression of stress responses
• stopping wheat which results in rapid rises of insulin
• stopping gluten/wheat/barley/rye
• stopping beans, peanuts, legumes (lectins)
• stopping dairy (which contain opioid-like proteins like wheat)
• stopping grains (rice, corn, etc) -- which are all grass-derived (*ha * I didn't say WEEDS but that's what I mean)
• proper nutrients which are the building-blocks of the Thyroid Gland and Thyroid Enzymes: proteins (taurine, leucine, arginine, OKG, L-carnitine, etc), minerals (IODINE, Mg, Zn, Se, Chromium, Bo, etc)
• B-vitamins (including α-lipoic acid)
• Vitamin D3 (goal 25(OH)D=70 ng/ml)
• Vitamin E (tocopherols, tocotrienols)
• Vitamin K1 K2
• Vitamin A
• Carotenoids (grassfed meat, wild seafood, Krill oil/Astaxanthin)
• EPA + DHA (ditto) -- high dose if extreme inflammation is present
• Antioxidants (Flavonoids, CoQ10, ALCAR/α-LA, Pycnogenol, etc)
• Avoid dietary and environmental toxins (nitrite preservatives, plastic, petroleum, bisphenol, heavy metals (Lead, Mercury), endocrine disrupters, pesticides, dioxins, etc)"

The Adrenal Connection

The adrenals are star-shaped endocrine glands that sit on top of our kidneys. Their main function is to regulate our stress hormones (cortisol, adrenaline) as well as produce several key sex hormones (DHEA, aldosterone).

A common analogie is as follows:

The thyroid controls the rate at which our motors run when in idle.
The adrenals control the rate at which our motors run when in gear.

If you can't function well in gear (stressed out much?) then naturally your body will slow the motor down so you don't blow a gasket (down regulation of the thyroid).

Excessive cortisol production is what we want to prevent when keeping our adrenal glands healthy. Besides leaving the Crackberry at home, getting good sleep, and having a positive outlook, we can minimize cortisol by regulating our blood sugar. 

This is of course is done by carbohydrate restriction. A surge of blood sugar induces the sympathetic nervous system into a state of over-arousal causing the adrenal glands to release adrenaline. This shifts your body into a biological state called "fight or flight". When chronically activated this response rewards us with stress induced eating, anxiety, and insomnia. Don't get me wrong, this evolutionary trait is not dangerous, but it's chronic activation with sugary foods is not what evolution intended.

Dietary fat plays a large supporting role in the health of our adrenal glands. In an experiment Hans Selye, M.D., author of The Stress of Life, exposed a large number of rats to environmental and physical stressors over long periods of time to test the resistance of the animals in repeated intervals.

This is what he wrote:  

". . . in one experiment we placed a hundred rats in a refrigerated room where the temperature was near freezing. (This causes the animals stress). Thanks to their fur during the first 48 hours they developed the typical manifestations of the alarm reaction. This was proved by killling ten animals at the end of the second day; all of them had large, fat-free adrenals, small thymuses, and stomach ulcers."  

Seyle concludes that the adrenals use large amounts of fat during stress. The reason the adrenal glands are surrounded by fat is in order to have the raw materials to synthesize hormones. When the fat is dried up, from chronic stress, we begin to deteriorate and soon after run into adrenal fatigue. Making an effort to consume plenty of essential fatty acids from grass-fed animals will go a long way in the battle of chronic stress and thyroid problems.

Nutritional Deficiencies

Scientists feed animals high carbohydrate diets to induce vitamin and mineral deficiencies. This is no different in humans. When you're body is under stress (high blood sugar, physical or mental stress) the body body will pull reserves of vitamins (vitamin B5), minerals (zinc), and amino acids (lysine, tyrosine, BCAA's) to combat the stress. Cortisol production requires tyrosine, the same amino acid needed to make thyroxine (T4). The bodies need to make cortisol in a "fight or flight" response will always trump the production of thyroid hormones. Essentially the more cortisol the body produces, the less raw materials available to make thyroid hormones.

As I have mentioned before, animal foods contain all the the amino acids, vitamins and minerals, in a bioavailable form that can sustain anyone indefinitely. Forget the vitamin pills and invest in quality meats from local grass-fed farms.

Environmental

My newest fascination has yet again found its way into my posts. Heavy metals (specifically mercury and lead) have devastating impact on adrenal and thyroid function. It has been demonstrated that mercury vapor accumulates in the adrenal cortex of animals causing a large increase in oxidative stress.

The production of steroid hormones from the adrenal glands is mediated by enzymes. Heavy metals are known to interfere with the action of many of these vital enzymes interupting the downstream of adrenal steroid production. Mercury for instance will disable the enzyme cytochrome P-450 which helps convert cholesterol into pregnenolone, a hormone used to make cortisone, aldosterone and DHEA. This enzyme disruption causes hormonal chaos and will last until measures are taken to get rid of the offending metals.

Conclusion

You cannot correct one gland without having a profound effect on another. This is why I believe that nutrition is the best medicine. Optimizing EVERY system in the body is the only way to get everything back on track. Simply treating low thyroid with medication is silly when we can clearly see that the origin can be multifaceted; rooted in stress, allergies, or even environmental pollution.

If you come away with two things from this post let them be that grains are shit and avoid stress whenever possible. A carnivorous diet poses no threat to anyones thyroid. In fact if you are hypothyroid it's likely that you already eat too many carbohydrates, seeming that most cases are autoimmune or stress related in origin. Carbohydrate consumption in the form of easily digestible sugars and gluten containing grains have a negative impact on the thyroid and adrenal glands. My recommendation would be to minimize or eliminate them completely.

Update on Wednesday, December 9, 2009 at 5:19PM by Danny Roddy

Here is a link to the updated post.

A few forum members have pointed out that very low carbohydrate diets cause an elevation in reverse T3 (inactive T3 thyroid hormone). Apparently this is the reason everyone MUST EAT 50 grams of carbohydrates a day.

I will state here, I am not an expert and I don't pretend to be. My point of interest is that zero-carbers have a high success rate. The proclaimed crashing of the metabolism due to elevated reverse T3 does not jive with the real life results. I also reject the idea that low-carbers need to take thyroid pharmaceuticals to be healthy.

Here is a snippet of the study that's being tossed around.

Starvation has a profound effect on thyroid function, causing a decrease in serumT3 concentration and a reciprocal increase in rT3 level. These changes are due to a selective inhibition of the 5’-monodeiodination of iodothyronines by peripheral tis-sues. Reduction in carbohydrate intake rather than total calorie deprivation appearsto be the determinant factor. These alterations in thyroid function are believed to re-duce the catabolic activity of the organism and thus to conserve energy in the face of decreased calorie intake. Chronic malnutrition is accompanied by similar changes.Over feeding has opposite although transient effects.

But wait, there's more.

To evaluate the effect of caloric restriction and dietary composition on circulating T3 and rT3 obese subjects were studied after 7-18 days of total fasting and while on randomized hypocaloric diets (800 kcal) in which carbohydrate content was varied to provide from 0 to 100% calories. As anticipated, total fasting resulted in a 53% reduction in serum T3 in association with reciprocal 58% increase in rT3. Subjects receiving the no-carbohydrate hypocaloric diets for two weeks demonstrated a similar 47% decline in serum T3 but there was no significant change in rT3 with time. In contrast, the same subjects receiving isocaloric diets containing at least 50 g of carbohydrate showed no significant changes in either T3 or rT3 concentration. The decline in serum T3 during the no-carbohydrate diet correlated significantly with blood glucose and ketones but there was no correlation with insulin or glucagon. We conclude that dietary carbohydrate is an important regulatory factor in T3 production in man. In contrast, rT3 concentration is not significantly affected by changes in dietary carbohydrate. Our data suggest that the rise in serum rT3 during starvation may be related to more severe caloric restriction than that caused by the 800 kcal diet.

What we have here is two seemingly good studies, in complete opposition of each other. The later was specifically conducted with individuals eating a zero carb diet.

Both of these studies do not include what the rest of the diet was composed of. Without knowing what the subjects ate, we are left guessing whether they were predominantly eating fat or protein. Dietary fat, the critical macro nutrient for maintaining the health of the adrenal glands, seems like it could potentially alter any outcome of a stress related study. 

Again, blaming the lack of the macro nutrient, that likely was the cause of the derangement in the first place is pretty silly. Those with thyroid disorders should be far more concerned with the intimate connection between insulin resistance, cortisol and reverse T3.

The stress hormone cortisol blocks production of T3 and causes an increase in the production of inactive reverse T3. Elevated levels of insulin lead to the over-arousal of the sympathetic nervous system (SNS). Chronic over stimulation of the SNS leads to the unnecessary production of cortisol, pooped adrenals, and eventually a sluggish thyroid.

HIGH BLOOD SUGAR > INSULIN > SNS HYPER-FUNCTION > ANGIOTENSIN II > ACTH ACTIVATION > UNNECESSARY CORTISOL > REVERSE T3

My stream of thought:

• Ditch the carbs.
• Eat until satisfied.
• Eat mostly fat, moderate protein.
• Get enough sleep.
• Take your vitamin D.
• Stay away from gluten.
• Call it a day.