The Carnivore Diet and Thyroid Autoimmunity

Note: this is the third blog post in a series of diet-related posts. Please check out my previous posts on the ketogenic diet and Paleo diet.

I’d like to begin by letting you know that I currently don’t recommend a carnivore diet to my patients, and while I do eat meat, overall I eat more of a plant-based diet.  That being said, some of the concepts behind a carnivore diet make sense.  The carnivore diet is based on the premise that animal foods are more nutrient-dense and bio-available than plant-based foods, and they also have the smallest amount of toxins.  And I will admit that the latter statement is almost definitely true, as even many proponents of a plant-based diet agree that there are potentially harmful toxins in plant-based foods.

Two examples include lectins and oxalates.  In fact, well-known cardiologist Dr. Steven Gundry recommends more of a plant-based diet, yet he realized that many plants have toxic compounds, which is what led him to write the book “The Plant Paradox”.  However, it’s also important to mention that not all plant-based foods are equivalent, and so while Dr. Gundry’s research shows that grains should probably be avoided, he does recommend certain types of nuts, as well as properly prepared legumes (i.e. pressure cooked).

What is a Carnivore Diet?

A strict carnivore diet involves eating only animal-based foods (i.e. red meat, poultry, organ meat, fish, eggs) while avoiding all plant-based foods (vegetables, fruit, nuts, seeds, grains, legumes).  The main reason why these foods are excluded is to avoid certain toxins, which include lectins, phytates, glycoalkaloids, and oxalates.  In his book “The Carnivore Code”, Dr. Paul Saladino discusses 5 different types of carnivore diets.  His “Tier one” diet involves eating mostly animal-based foods, but allows a small amount of the least toxic plant foods.  In his book he discusses the least and most toxic plant foods, although another excellent book that relates to this is “The Plant Paradox”, written by Dr. Steven Gundry.

I won’t discuss all five of the diets in Dr. Paul’s book, but I’ll mention that his “Tier five” diet excludes all plant-based foods.  Some of the foods he recommends to eat on this “Tier 5” diet include grass-fed muscle meat, connective tissue, seafood, and eggs.  It also involves eating a lot of organ meats.

Why Do People Choose To Follow a Carnivore Diet?

Many people choose to be a vegan or vegetarian because 1) they think that it’s healthier, or 2) they think it’s unethical to eat animals.  I don’t think that most people initially follow a carnivore diet because they think that all plant-based foods are unhealthy, and of course they’re not doing it because they think it’s unethical to eat plants.  The two main reasons are because 1) they are trying to lose weight and nothing else has worked, and 2) they have some type of health condition they’re looking to overcome.

How Can a Carnivore Diet Help with Graves’ Disease and Hashimoto’s?

Although I can’t say that I’ve had patients follow a strict carnivore diet, there are people with different types of autoimmune conditions who have found a carnivore diet to be life changing.   Obviously the same can be said for many other diets that involve eating whole foods, while avoiding refined foods and sugars, fast food, etc.  And while I’m sure there are people who haven’t done well on a Paleo or autoimmune Paleo (AIP) diet yet thrived on a carnivore diet, this is just proof that there is no diet that fits everyone perfectly.

An autoimmune Paleo diet involves avoiding most of the plant-based foods that are harsher on the gut and can potentially result in inflammation.  But without question there are people who don’t do well with the “allowed” plant-based foods, and thus they might do better on a carnivore diet.  It’s also worth mentioning that many of the AIP allowed foods are high in oxalates (i.e. spinach, sweet potatoes), which in some cases can cause pain, kidney stones, and other health issues. This doesn’t mean that you can never eat these foods, although it probably is a good idea to minimize your consumption of them.  For example, if you’re stuffing your smoothies with spinach like I used to do then you might want to reduce the amount of spinach you eat.

Can a Carnivore Diet Disrupt the Gut Microbiome?

In my recent blog post entitled “Can a Ketogenic Diet Benefit Those with Graves’ and Hashimoto’s?“, I discussed whether or not a ketogenic diet can negatively affect the gut microbiome.  I brought up a few different studies, and concluded that more research needs to be done, and to play it safe it might be a good idea to supplement with prebiotics when following such a diet.

Although there is no research I’m aware of that looks at the gut microbiome of people following a strict carnivore diet, one randomized controlled trial compared a vegan diet vs. a meat-rich diet, and after 4 weeks it showed that overall the gut microbiota was not remarkably altered between both diets (1).  So most of the participants showed a similar microbiota composition at the start and the end of the trial, which is encouraging for those who choose to eat mostly animal-based foods.  But of course four weeks is a short period of time.

One of the main concerns with avoiding plant-based foods is that there won’t be dietary fibers to support the flora of the gut.  Once again, this is disputed by advocates of the carnivore diet, as they claim that the body will adapt.  I’m not arguing this, but I still think more research needs to be done before we can conclude that a 100% animal-based diet won’t have any negative consequences on the gut microbiome when followed for a prolonged period of time (i.e. at least one year in duration).

Can a Carnivore Diet Cause Nutrient Deficiencies?

Advocates of the carnivore diet claim that eating a strict carnivore diet won’t result in nutrient deficiencies as long as you eat a variety of organ meats.  Although I can’t say I eat organ meats, I agree that they are very nutrient dense.  That being said, because of the lack of research demonstrating whether eating a diet consisting of 100% animal-based foods will result in nutrient deficiencies, even if one chooses to predominantly eat animal-based foods, I still think it would be wise to eat some plant-based foods as well.

Can a Carnivore Diet Increase Cardiovascular Risk?

While in the past there were some concerns about eggs increasing cardiovascular risk by raising cholesterol levels, this has been debunked (2) (3).  Currently most of the concerns with animal-based foods are with red meat, as there are numerous studies that show a relationship between red meat consumption and heart disease (4) (5).  While this might be attributed to eating unhealthy forms of red meat, one also needs to take into consideration that many people who eat “unhealthy” forms of red meat on a regular basis also incorporate other unhealthy habits.  For example, someone who eats non-organic, grain-fed beef probably is more likely to eat other lower quality foods than someone who regularly consumes grass fed/grass finished beef.

In 2015 I released an article entitled “Is Red Meat Harmful For Those With Graves Disease and Hashimoto’s Thyroidits?“.  In this article I argued that eating healthier forms of red meat (i.e. 100% grass fed beef) probably doesn’t carry the same health risks as unhealthier forms.  That being said, I can’t say that I eat red meat on a daily basis, but I’m not necessarily avoiding it on a regular basis, as I do eat it a few times per week.

Can other sources of animal-based foods increase cardiovascular risk? 

It’s important to mention that while most people who follow a carnivore diet probably eat red meat, those who follow this diet probably should eat other types of meat as well.  And the research seems to show a decreased cardiovascular risk when eating other forms of animal-based foods.  This includes poultry and fish (6) (7) (8).  Once again, none of these studies takes into account healthier forms of red meat.

Did Our Ancestors Follow a Carnivore Diet?

Although it does appear that some ancestral groups ate large amounts of animal-based foods, they didn’t exclusively eat this way.  They did eat some plant-based foods at times, and so while I do recommend more of a plant-based diet to my patients, if you eat a lot of meat I would still recommend to eat some vegetables.  You just want to try to avoid the least toxic plant-based foods while trying to restore your health.

Is It Safe To Follow a Strict Carnivore Diet Long Term?

Unfortunately I wasn’t able to find any long term studies involving people following a 100% carnivore diet.  On a short term basis it probably is fine to follow this.  But on a long term basis it is unknown.  I’m sure if you visit some of the carnivore diet Facebook groups there will be people who have followed this diet for many months, and probably some for years and who seem to be in a good state of health.  And if this describes you then please feel free to share your experience in the comments section below.

Have YOU Followed a Carnivore Diet?

If you have followed a carnivore diet, or are currently following one, then I’d love to hear from you! Whether you have followed a carnivore diet for a few weeks, months, or years, please share your experience in the comments section below.  If you followed a carnivore diet and it greatly improved your health please let me know! And if you followed a carnivore diet and you didn’t notice any improvements I’d also like to know!