There are numerous drugs that help people to feel calmer by reducing anxiety and relaxing the muscles. Perhaps the most well-known is Valium (diazepam), which is one of a group of medications called benzodiazepines. Benzodiazepines have been used since the 1950s to treat conditions such as anxiety, sleep problems, and epileptic fits. However, like other anti-anxiety drugs, they can have side effects including amnesia (memory loss) and ataxia (disorders that affect co-ordination, balance and speech). So, some researchers have been exploring safer options .
One possibility is flavonoids, a class of phytochemicals (chemical compounds that occur naturally in plants) found in foods such as berries, cocoa and tea. They work in a similar way to anti-anxiety drugs.
Anti-anxiety drugs boost the effects of a substance in the brain called GABA (Gabba Amino Butyric Acid). As explained by the Royal College of Psychiatrists: “[GABA] is a neurotransmitter – a chemical which is used in the brain to control the passage of messages from one cell to another. GABA has a generally calming effect in the human brain.” 
Cell and animal studies suggest that flavonoids can do the same thing . They are able to pass the blood-brain barrier and attach themselves to the brain’s anti-anxiety receptors, having a calming effect without the side effects of medication. So, while we can’t prove that this definitely applies to humans, it’s worth adding flavonoid-rich foods to your daily diet for their anti-anxiety properties.
Here is a list of some of the foods highest in flavonoids. The good news is that cacao beans, the raw ingredient from which chocolate is made, are at the top of the list! Tea and cocoa powder also make an appearance:
Cacao beans 8606 mg flavonoids/100 grams*
Elderberry juice concentrate 520
Blackberry juice concentrate 355
Raw black raspberries 324
Raw bilberries 289
Dry unsweetened cocoa 261
Carob flour 236
Fresh parsley 233
Raw radicchio 204
Raw blackberries 138
Raw wild blueberries 133
Brewed green tea 120
Brewed black tea 119
Raw cranberries 99
Raw red currants 79
Raw kumquats 79
Blackcurrant juice 78
Brewed white tea 75
Raw concord grapes 73
Raw arugula 69
Raw mustard greens 63
Frozen acai berries 62
* Milligrams of flavonoids per 100 grams of fresh weight of edible portion.
 The research referred to above is listed at the end of this article by Deanna Minich, PhD: “Feel Anxious and on Edge? Get More of These Flavonoid-Rich Foods!”
And if you’ve never heard of black raspberries (I hadn’t!), here is a fact sheet from ‘Black Raspberries: Developing the Genomic Infrastructure for Breeding Improvement’, a research project involving members of the United States Department of Agriculture’s Agricultural Research Service…