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.

What are your experiences with consuming chocolate?


  1. Seligson FH, et al . Patterns of chocolate consumption, 1994

  2. Dillinger TL, et al. Food of the gods: cure for humanity? A cultural history of the medicinal and ritual use of chocolate, 2000

  3. www.caobisco.com/doc_uploads/Charts/ranking_of_consumption_chocolate_confectionery_2007.pdf

  4. McShea A, et al. The essence of chocolate: a rich, dark, and well-kept secret. 2009

  5. Katz DL, et al. Cocoa and Chocolate in Human Health and Disease, 2011

  6. Bracco U. Effect of triglyceride structure on fat absorption, 1994

  7. Jenkins DJ, et al. Effect of cocoa bran on low-density lipoprotein oxidation and fecal bulking, 2000

  8. Sternberg FM, et al. Keen CL. Cocoa and chocolate flavonoids: implications for cardiovascular health, 2003

  9. Court R, et al. Cocoa and cardiovascular health, 2009

  10. Rein D, et al. Cocoa inhibits platelet activation and function, 2000

  11. Selma C, et al. The anti-inflammatory properties of cocoa flavanols, 2006

  12. Shapiro H, et al. Polyphenols in the prevention and treatment of sepsis syndromes: rationale and pre-clinical evidence, 2009

  13. Jia L, et al. Short-term effect of cocoa product consumption on lipid profile: a meta-analysis of randomized controlled trials, 2010

  14. Johnston K, et al. Dietary polyphenols decrease glucose uptake by human intestinal Caco-2 cells, 2005

  15. Kenny TP, et al. Cocoa flavanols and procyanidins can modulate the lipopolysaccharide activation of polymorphonuclear cells in vitro, 2009

  16. Mackenzie GG, et al. Epicatechin, catechin, and dimeric procyanidins inhibit PMA-induced NF-kappaB activation at multiple steps in Jurkat T cells, 2004

  17. Williams S, et al. Eating chocolate can significantly protect the skin from UV light, 2009

  18. Sober C et al. Trigger factors of migraine and tension-type headache: experience and knowledge of the patients, 2006

  19. Matsui N, et al. Ingested cocoa can prevent high-fat diet-induced obesity by regulating the expression of genes for fatty acid metabolism, 2005

  20. Massolt ET, et al. Appetite suppression through smelling of dark chocolate correlates with changes in ghrelin in young women, 2010

  21. el-Saadany SS. Biochemical effect of chocolate colouring and flavouring like substances on thyroid function and protein biosynthesis.

  22. de Souza dos Santos MC, et al. Impact of flavonoids on thyroid function, 2011

  23. Hamper R, et al. Short-term effect of soy consumption on thyroid hormone levels and correlation with phytoestrogen level in healthy subjects, 2008

DietVedrana Högqvist Tabor