I think I’ve mentioned here before that I’m a big fan of chocolate. I get upset when coffee shops in my area only bring out the chocolates in the afternoon. Who says you can’t have a chocolate chip cookie for breakfast?
Chocolate, combined with a cup of coffee, helps me work all the way through to the end of the day, when I’d otherwise be tempted to call it quits in the late afternoon. So naturally I was excited when Greta found a research report on the effect of chocolate on mood. Could there be scientific confirmation that chocolate helps you get through the day?
There has been plenty of research suggesting that many people eat in response to negative moods and stress, but there is less evidence that eating actually improves mood. Many of the studies done on emotional response to food have been poorly controlled. Others have shown that mood can improve as a result of nutrient consumption — but this impact may be delayed for some time. Michael Macht and Jochen Mueller wanted to know if eating chocolate could immediately improve mood.
They recruited 48 volunteers via classified ads, all of whom said they liked chocolate. The volunteers reported their mood (on a scale from 1 [negative] to 25 [positive]), then watched one of three short movie clips: A mourning scene from “The Champ,” the Meg Ryan orgasm scene from “When Harry Met Sally,” or a clip from a documentary about copper manufacturing. As you’d expect, the first clip had been previously shown to induce negative mood, the second, positive mood, and the third, no mood change. After viewing the clips, the volunteers reported their moods, and their moods had changed as predicted.
Then half the volunteers were given a piece of chocolate, and the unlucky second group got a glass of water. 1 minute later, they reported their mood once again. This was repeated for each clip (the clips were shown in a random order for each participant). So did chocolate have a different effect from water? Here are the results:
As you can see, the effect of chocolate depends on the type of movie the viewers watched. If the movie was sad, then eating chocolate led to a significant improvement in mood, significantly better than water. For a happy film, there was no improvement in mood, and the difference between chocolate and water was only marginally significant. For a neutral movie, there was no significant difference in the effect of chocolate and water.
The volunteers were also surveyed about their eating habits, and there was a significant positive correlation between those who were emotional eaters (who ate at times of stress) and mood improvement after a sad movie. In other words, emotional eaters get a big boost from eating chocolate, while people who exhibit dietary restraint do not (though since this is only a correlation, we can’t say why it’s happening).
The next question Macht and Mueller had was whether there was something about the chemical or nutritional properties of chocolate that improved mood after a sad movie clip, or it was simply related to the pleasurable taste of chocolate. They recruited 113 new volunteers, and this time, they surveyed them first about their preferred and least-favorite type of chocolate: Milk chocolate, or 70, 85, or 99 percent dark chocolate. Everyone was shown the sad clip, and then one group was given their preferred type of chocolate, another group got their least favorite type of chocolate, and the final group got nothing. Here are those results:
After one minute, the group eating their preferred (palatable) chocolate was in a significantly better mood. The group eating their least-favorite (unpalatable) chocolate was unchanged. But after three minutes, there was no difference between the palatable and unpalatable chocolate-eaters. So the initial improvement in mood is very likely due to the pleasant taste of chocolate, but after a few minutes, mood improvement may be more related to the nutritional or chemical properties of chocolate.
All in all, I see nothing here to change my current pattern of an afternoon dose of chocolate to motivate me to work through the day. Hooray for chocolate!
One important additional line of research Macht and Mueller would like to see done in the future:
Further studies should address the question of whether mood effects over longer periods of time may result from consumption of a greater amount of chocolate.
Sign me up!
MACHT, M., & MUELLER, J. (2007). Immediate effects of chocolate on experimentally induced mood states Appetite, 49 (3), 667-674 DOI: 10.1016/j.appet.2007.05.004