This development is relevant because one common and accepted theory regarding the cause of anxiety involves a chemical imbalance in the brain, with the most likely culprit being serotonin. Serotonin is synthesized from the amino acid tryptophan, with both iron and vitamin B6 playing a significant role in this process. An absence of these nutrients can cause a decrease in serotonin levels. A decrease in serotonin is believed to trigger anxiety disorders.
https://www.disclose.tv/study-links-anxiety-and-panic-attacks-to-vitamin-deficiencies-351310