In a recent study published in PLOS ONE, researchers investigated whether consuming different cocoa products in different proportions could lower pain experimentally induced by injecting hypertonic saline into the masseter muscle of healthy individuals.
Pain is an international health concern that worsens life quality and has significant financial implications for patients, healthcare providers, and society. Pain can be acute or chronic, as well as nociceptive, neuropathic, idiopathic, or nociplastic.
Tryptophan, critical for serotonin synthesis and a vital amino acid in chocolate, is linked to cocoa. Flavanol-rich cocoa-derived products can help decrease inflammation. Animal studies showed that cocoa-rich diets lower pain associated with neuroinflammation, implying that cocoa could be used as an alternative pain treatment.
About the study
In the present experimental, double-blinded, randomized controlled trial, researchers investigated whether consuming products with differing cocoa content would affect pain induced by injecting hypertonic saline into the masseter muscle of healthy male and female Swedish individuals.
The study was conducted between 1 March and 20 December 2020, including 30 young adults (15 males and 15 females) aged ≤40 years, involving three follow-up visits with a washout period of ≥7.0 days. The team induced pain two times during every visit by intramuscularly injecting 0.20 mL of 5.0% hypertonic saline, pre- and post-consumption of 3.60 grams of dark, white, or milk chocolate containing 70%, 34.0%, and 30.0% cocoa, respectively.
Pressure pain threshold (PPT) and pain duration, site, and peak intensity were evaluated every five minutes following the saline injection for over 30 minutes. The team excluded individuals diagnosed with painful conditions of the orofacial areas or temporomandibular joint, headaches, musculoskeletal diseases (rheumatoid arthritis or fibromyalgia), whiplash injuries, neurological diseases, psychiatric diseases, or saline allergies.
All individuals completed questionnaires concerning psychosocial well-being at the initial visit, including anxiety, somatization, depression, stress, and pain catastrophizing, using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis II criteria.
In addition, to evaluate emotional well-being, the team used the Generalized Anxiety Disorder Screener (GAD-7), the Patient Health Questionnaire (PHQ)-9 and 15, the 13-item Pain Catastrophizing Scale (PCS-13), and the 10-item Perceived Stress Scale (PSS-10). The Visual Analogue Scale (VAS) was used to assess pain intensity.
Results and discussion
The mean ages of the male and female participants were 24 and 25 years, respectively. Most (27 of 30) individuals preferred milk chocolate, with mean scores for milk, white, and dark chocolate of 2.7, 2.4, and 1.9 points, respectively. White chocolate consumption significantly reduced pain intensity after 105 to 210 seconds of inducing pain.
Among males, white chocolate significantly lowered the intensity of pain 60 to 240 seconds after pain induction. However, white chocolate intake did not result in significant differences, and the interactions between time and white chocolate intake were non-significant. Likewise, the interactions between milk chocolate intake and duration were non-significant.
However, among females, milk chocolate significantly reduced pain intensity after 255 seconds of inducing pain. Among men, dark chocolate intake significantly reduced pain intensity at 75 to 210 seconds of inducing pain, whereas the interactions between dark chocolate intake and duration were non-significant.
Further, white chocolate reduced pain intensity after 165.0 seconds to four minutes of pain induction among males more significantly than among females. Consuming white chocolate and milk chocolate lowered the peak values for pain intensity by three percent and seven percent, respectively. However, consuming any chocolate did not significantly impact the PPT, duration, or spread of the induced pain. The changes in pain experiences may have been limited due to the small quantity of chocolate intake.
Milk and white chocolate lowered pain more effectively than dark chocolate, which may have been due to the difference in the concentration of sugar, an ingredient with analgesic properties due to opioid release. Moreover, positive experiences concerning the taste of food can stimulate the brain to secrete neurotransmitters and endorphins that increase tolerance to pain. Therefore, the most preferred milk chocolate may have a greater impact on pain intensity than white chocolate, despite similar cocoa concentrations. The results were the least significant for dark chocolate, likely due to its low sugar content and bitter taste.
Overall, the study findings showed that eating chocolate (irrespective of type) five minutes before a painful stimulus can significantly reduce pain intensity, particularly following white chocolate intake among males. The findings indicated ingredients other than cocoa in chocolates, such as sugar, and preferences and taste experiences might explain the pain-lowering effects of chocolates.
- Hajati, A. et al. (2023) "Chocolate intake and muscle pain sensation: A randomized experimental study", PLOS ONE, 18(5), p. e0284769. doi: 10.1371/journal.pone.0284769.