If you drink coffee or consume other forms of caffeine (i.e. green tea, dark chocolate), then I think you’ll find this blog post to be interesting. I’ll be discussing five things about caffeine, with an emphasis on coffee. And while not all five points will relate to thyroid health, I do think those who drink coffee daily or consume other forms of caffeine will find the information in this post to be valuable.
So let’s get started…
1. Caffeine is the most widely consumed psychostimulant substance. This is why many people with thyroid and autoimmune thyroid conditions love their morning coffee. And as a result of this, there are many people who are willing to give up gluten and dairy, but refuse to give up drinking coffee. Others are willing to give up coffee, but it’s a major struggle. This of course brings up the question “does everyone with a thyroid or autoimmune thyroid condition need to give up coffee?”
The truth is that everyone is different, and some people are able to get away with drinking coffee, while others aren’t. But the same thing holds true with other foods, including eggs, nightshades, nuts and seeds, grains, etc. But because it’s hard to predict whose health will improve while continuing to drink coffee, and who won’t progress while drinking it, in most cases I will recommend for my patients to take a break from it while trying to restore their health.
2. Caffeine might benefit the immune system of those with Graves’ Disease and Hashimoto’s Thyroiditis. This might sound exciting for those who have an autoimmune thyroid condition, as there is research which shows that caffeine can decrease both Th1 and Th2 cytokines (1)  (2) . Hashimoto’s Thyroiditis is typically characterized by an increase in Th1 cytokines, while most cases of Graves’ Disease involve an increase in Th2 cytokines. This doesn’t mean that drinking a few cups of coffee will suppress the autoimmune component, although it suggests that drinking coffee, green tea, or eating dark chocolate won’t exacerbate the autoimmune response.
I’ll add that there was also a 2017 journal article where the authors mentioned that while coffee consumption may exert a protective role against multiple sclerosis, primary sclerosing cholangitis, and ulcerative colitis, it might increase the risk of developing rheumatoid arthritis and type 1 diabetes mellitus (3) . However, when I did research on rheumatoid arthritis and coffee consumption I came across a few studies which showed that there was no significant association between coffee consumption (caffeinated or decaffeinated) and rheumatoid arthritis (4)  (5) . And I also wasn’t able to find evidence that coffee consumption increased the risk of type 1 diabetes, although there were numerous studies which showed that coffee and caffeine might significantly reduce the risk of developing type 2 diabetes (6)  (7) .
3. Instant coffee can cause an increase in gluten antibodies. A study showed that significant immune reactivity was observed when gliadin antibodies were applied to cow’s milk, milk chocolate, milk butyrophilin, whey protein, casein, yeast, oats, corn, millet, instant coffee, and rice (8) . Gliadin is a protein found in gluten, and what I mentioned here is an example of something called cross-reactivity.
This study was conducted by Dr. Aristo Vojdani, who is the Chief Scientific Advisor of Cyrex Labs. And this research is the basis behind the Cyrex Labs Gluten-Associated Cross-Reactive Foods and Foods Sensitivity test, which is also known as their Array #4. It’s also important to mention that in the study they used instant coffee, and according to Dr. Vojdani, if you drink a good quality organic coffee then you probably don’t have to be concerned about this cross reacting with gluten.
4. Coffee can interfere with the intestinal absorption of thyroid hormone replacement. Studies show that drinking coffee can decrease the intestinal absorption of thyroxine (9)  (10) . Although these studies used levothyroxine, which is synthetic T4, if you are taking natural thyroid hormone replacement (i.e. Armour, Nature-Throid, WP-Thyroid) it still is a good idea not to drink coffee at the same time. As for how long should you wait to drink coffee after taking thyroid hormone replacement, the research suggests to wait one hour. Just to be clear, these studies were specific to coffee, and not caffeine in general. And so for those who drink caffeinated green tea, this doesn’t seem to interfere with thyroid hormone absorption, and I wasn’t able to find any studies which suggested that it does this.
5. Caffeine should be avoided by those who have adrenal problems. This is the main reason why I recommend for my patients with Graves’ Disease and Hashimoto’s Thyroiditis to take a break from caffeine while restoring their health, as it can have a negative effect on the health of the adrenals by increasing cortisol secretion (11)  (12) . And of course many people with these conditions have adrenal problems.
Since caffeine can increase cortisol secretion, it makes sense for those who have elevated cortisol to avoid caffeine. But does this mean that it’s okay for those who have depressed cortisol levels to consume caffeine? Well, we need to keep in mind that taking something like caffeine that stimulates cortisol production isn’t addressing the cause of the problem. But more importantly, consuming caffeine in those with depressed cortisol levels can worsen the adrenal problem, and so you really do want to do things to improve the health of the adrenals.
It’s also worth mentioning that caffeine is metabolized differently by different people. In other words, some people are considered to be “fast metabolizers” of caffeine, while others are “slow metabolizers”. Regardless of whether someone is a “fast” or “slow” metabolizer of caffeine I recommend for them to take a break from drinking coffee while restoring their health. But if someone is a “fast metabolizer” of caffeine then they probably can reintroduce it in the future without a problem. On the other hand, if someone is a “slow metabolizer” then they might want to consider giving up coffee for good, or at least minimizing their consumption of it. And the reason for this is because there are certain health risks associated with being a slow metabolizer of caffeine, including an increased risk of having a heart attack (13) .
But how can you tell if you are a “slow” or “fast” metabolizer of caffeine? If you feel wired after drinking coffee then there is a pretty good chance that you are a slow metabolizer. Or if you have problems falling asleep even if you drink coffee earlier in the day, then this is another sign, although of course the sleep problems can be related to something else. On the other hand, if you are able to drink coffee later in the day and sleep like a baby, then chances are you are a fast metabolizer.
Genetic testing can also determine if someone is a “slow” or “fast” metabolizer of caffeine, as caffeine is measured by an enzyme called cytochrome P450 1A2, which is also known as CYP1A2. If someone has the A/A genotype then this means they are a fast metabolizer of caffeine. On the other hand, having either the A/C or C/C genotype means that they are a slow metabolizer.
So hopefully you have learned a few things about caffeine and coffee that you didn’t know before. Many people love drinking coffee, and while I recommend for most of my patients to take a break from it while restoring their health, I realize that some people need to wean off slowly. And although coffee and caffeine might have some health benefits, caffeine can cause problems in those who have adrenal imbalances and/or those who are slow metabolizers of caffeine. In addition, coffee can interfere with the absorption of thyroid hormone medication, and so you definitely don’t want to drink coffee around the same time you take levothyroxine or desiccated thyroid.