A new study by Nestlé researchers suggests that eating a few pieces of dark chocolate every day may improve the metabolic response of people who
report feeling highly stressed.
The study, which was published in the Journal of Proteome Research, was the work of lead investigator Sunil Kochhar, a researcher at the Nestlé Research Center in Lausanne, Switzerland.
Anxiety and stress can cause various changes in physical and emotional states in humans, and in the longer term can also lead to serious health consequences.
Other studies have already shown that diet affects human metabolism through its influence on gut bacteria, and this too can have long term health consequences.
For this study, Kochhar and colleagues investigated the metabolic response in a group of 30 healthy adult volunteers who were asked to consume two portions of 20g of dark chocolate every day for up to 14 days.
The volunteers had already filled in validated psychological questionnaires from which the researchers were able to classify them into low and high anxiety traits.
To assess metabolic response, the researchers analyzed urine and blood plasma given by each volunteer during three test days at the beginning, the middle and the end of the 14 day period.
The main measures of metabolic response they looked at were stress-related metabolic changes such as energy metabolism and gut microbial activity.
Kochhar and colleagues wrote that they used nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) to study global changes in metabolism over the period of study.
The results showed that:
- Subjects with higher anxiety trait had a distinct metabolic profile.
- This profile was indicative of a different energy homeostasis (characterized by lactate, citrate, succinate, trans-aconitate, urea, and proline), hormone metabolism (adrenaline, DOPA, 3-methoxy-tyrosine), and gut microbe activity (methylamines, p-cresol sulfate, hippurate).
- Dark chocolate reduced the amount of stress hormone cortisol and catecholamines in the urine.
- Dark chocolate also partially normalized stress-related differences in energy metabolism (glycine, citrate, trans-aconitate, proline, β-alanine) and gut microbial activities (hippurate and p-cresol sulfate).
"The study provides strong evidence that a daily consumption of 40 g of dark chocolate during a period of 2 weeks is sufficient to modify the metabolism of free living and healthy human subjects, as per variation of both host and gut microbial metabolism."
Kochhar told the press that:
"Consuming dark chocolate daily can positively impact the metabolism of people that report having high-stress levels."
"These results strongly support our ongoing metabonomics research efforts to ascertain the impact of certain foods on human metabolism through the adaptation of gut microbial activities."
This is not the first study by the Nestlé Research Center to show that dietary choices, including chocolate, can significantly affect energy and gut bacteria metabolism.
They told the press this week that:
"Scientists at the Nestlé Research Center continue to strengthen their position that the gut ecology and metabolic activity of healthy individuals may be modulated by the diet."
"Metabolic Effects of Dark Chocolate Consumption on Energy, Gut Microbiota, and Stress-Related Metabolism in Free-Living Subjects."
Francois-Pierre J. Martin, Serge Rezzi, Emma Per-Trepat, Beate Kamlage, Sebastiano Collino, Edgar Leibold, Jrgen Kastler, Dietrich Rein, Laurent B. Fay and Sunil Kochhar.
Journal of Proteome Research, 2009
Published online ahead of print, Oct 2009.
Written by: Catharine Paddock, PhD