Dark chocolate and thyroid health
Today chocolate is often seen as an indulgent treat — but it hasn’t always been that way.
Historically, cacao and chocolate have been used by cultures around the world as a form of medication—just in case you needed a reason to justify that candy bar.
Humans have been consuming food made from cocoa beans since at least 460 AD, and probably even before (1).
A couple of centuries ago, cacao and chocolate were used for medical treatment, most commonly to improve brain function or digestion and to induce weight gain (2).
People around the world still consume a lot of chocolate, and often claim it improves their overall well-being.
An average person living in China eats 120 grams or 4.2 ounces of chocolate per year
An average person living in the US consumes 5.2 kg or 11.5 pounds of chocolate per year
An average person living in Ireland consumes 11.9 kg or 26.2 pounds of chocolate per year (3)
Facts about cocoa
Cocoa or cacao is the dried and fermented seed of the fruit of the cocoa tree (4). It contains vitamins, minerals, fiber, and molecules called polyphenols (4,5)
If ground, roasted, and shelled, cocoa becomes cocoa nibs.
Chocolate is made by combining cocoa and sugar, and the proportion of cocoa in the chocolate determines how dark the chocolate will be. The darker the chocolate, the more of its original content is preserved.
The oil in cacao is referred to as cocoa butter, and contains a mixture of good and bad fats (6). Cocoa butter is used to make chocolate, as well as in certain cosmetic preparations.
The bran of the cocoa bean is high in fiber, though commercial cocoa products have only some fiber left after processing. Research has shown that this fiber can improve the good-to-bad cholesterol ratio (7).
A 100 kcal chunk of unsweetened dark chocolate (70%-85% cocoa) contains 1.7g fiber
A 100 kcal chunk of milk chocolate contains 0.6g fiber
1 tablespoon of unsweetened cocoa powder contains close to 2g of fiber, and only 12 kcal (5)
The cocoa bean is rich in minerals, such as magnesium, copper, potassium, and calcium, which help keep the heart and blood vessels healthy; it also contains many different antioxidant molecules, collectively known as polyphenols (5, 8). The most well-known polyphenols are flavonoids, which help regulate the immune system (9) and reduce inflammation in the body (9–11).
Cocoa polyphenols can enhance the antioxidant function of vitamin C and selenium (12).
Dark chocolate may improve your health
Many research studies have shown that moderate consumption of dark chocolate (less than 100 g per day) significantly improves insulin sensitivity and sugar metabolism, lowers bad cholesterol, and normalizes blood pressure (5, 13, 14).
Chocolate has an effect on your gut, too: immune cells in the gut change in number and function with the increased consumption of dark chocolate or cocoa (15). Many of the molecules in our body that cause inflammation are reduced in number when eating dark chocolate or cocoa (5, 16). This can help with Hashimoto’s flare-ups.
Dark chocolate can reduce brain fog and help with improving long-term memory and focus (17, 18). It can also protect skin from UV light damage (19).
Eating smaller amounts, such as 20g or less per day, of dark chocolate or cocoa should not lead to an increase in weight (5). Indeed, some animal studies have shown that consuming cocoa can reduce fat (20).
Also, the smell of chocolate can suppress hunger (5).
What do you need to know when consuming chocolate for health?
To get the health benefits of chocolate or cocoa, it needs to contain an effective dose of the active components: flavonoids, minerals and vitamins. For that reason, dark chocolate is a much better choice than either milk or white chocolate.
It is good to know that even different types of dark chocolate have different amounts of the active components responsible for health benefits of chocolate. This happens because of the differences in cocoa bean processing during roasting and fermentation (5).
For that reason, it is always good to read the label on the chocolate package and make sure there are enough flavonoids. Labels will not typically state the amount of flavonoids in their product, but you can find out by seeing what type of processes were used to make the chocolate.
If you read “treated with alkali” or “dutching process”, those are indicators your chocolate is not as rich in flavonoids as it could be (5).
Some of the more notable negative effects of chocolate are acne and heartburn. Some people reported it induces migraines and weight gain (21, 5). All of these effects are less pronounced when consuming dark chocolate.
Effects of chocolate on thyroid function
In the case of the thyroid, artificial colors and flavors added to some chocolates can create an imbalance of thyroid hormones, specifically raising the levels of T4 hormone (5).
While cocoa flavonoids have many benefits, including reducing inflammation, stabilizing blood pressure, and the immune response, they might interfere with the thyroid function.
It has been shown that flavonoids from some other plants, most notably soybeans, can affect the amount of thyroid hormones available to different organs in the body (22). However, flavonoids found in chocolate are so far not reported to cause any such effect (23).
Chocolate is made to be enjoyed, and to bring extra happiness to our lives. Enjoying it responsibly, and in the right dose it might help your body feel better. If you can, choose dark chocolate over milk or white chocolate.
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Hamper R, et al. Short-term effect of soy consumption on thyroid hormone levels and correlation with phytoestrogen level in healthy subjects, 2008