The consumption of fermented products is on the rise as drinks like kombucha and kefir have become popular. They are a source of tryptophan, an amino acid critical to producing serotonin, the brain chemical that influences mood, and may also contain neurotransmitters in their raw form. Research has shown that eating fermented foods may have long- and short-term impacts on brain function, such as reducing stress.

Led by researchers at University College Cork, in Ireland, a new large study has begun to compare 200 fermented foods from around the world to pinpoint which ones are the most beneficial for brain health. Although still in its initial stages, preliminary results have already revealed some surprises. Almost all of the fermented foods display the potential to improve gut and brain health. While more research is needed, sugar- and vegetable-based fermented foods are likely to top the list, according to the lead researcher.