Grape extracts have been shown to contain high concentrations of dietary phytochemicals, particularly polyphenols. As polyphenols have been shown to possess possible anxiolytic effects in humans and animals, this may suggest that extracts of grape plants may confer mood elevating effects. For example, in one study researchers created a liquid extract of grape plants from the fruits of grape vines (grape juice). The researchers then administered this grape juice to a group of mice that were exposed to experimental stress. The juice was given orally and the dose was 4 or 8 mL per kg of body weight. This would be equivalent to 300 mL or 600 mL of juice to a 75 kg human subject. The researchers observed that the grape juice caused significant reductions in the anxious behaviour displayed by the mice, and also caused a significant increase in the movement of the mice (ambulation and rearing). These effects were not as great as for the drug diazepam, but were greater than those shown by the placebo.
Extracts from grape vines (Vitis vinifera) have been shown to contain high concentrations of polyphenols. In particular grape extracts contain both flavonoids and stilbenes, two important dietary classes of polyphenols. Grape juice and raisin extracts may contain polyphenols that are able to significantly elevate mood.
Therefore grape juice at a physiologically relevant dose may have significant anxiolytic effects. That the flavonoids in grape extracts may be responsible for their anxiolytic effects of grape extracts was demonstrated in another experiment. In this study, researchers extracted the flavonoid myricetin from raisins and administered this extract to mice. The mice were then exposed to experimental stress. The results of the study showed that the myricetin extracts were able to reduce the anxious behaviour caused by the drug meta-chlorophenylpiperazine. As this drug is known to cause effects on the serotonin system, and this is how it may induce anxiety, this perhaps suggests that the myricetin was able to modify the serotonin system and prevent the development of anxiety in the mice. Cell culture studies provided evidence to the researchers that the myricetin was able to modify the serotonin systems in rat brains. These results suggest that the grape flavonoid myricetin may confer some of the anxiolytic effects of grape extracts.
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