This clinical trial investigates the effects of Vitamin B6 supplementation on neural inhibition using electroencephalography (EEG), in relation to depression and anxiety symptoms in participants from the general population with a relatively high level of symptoms at baseline. Researchers will compare a placebo group to high-dose Vitamin B6 to test the hypothesis that Vitamin B6 moves the excitation/inhibition balance towards inhibition.

The primary question this trial aims to answer is:

- Compared to placebo, in people experiencing depression and anxiety symptoms, does high-dose Vitamin B6 supplementation change the excitation/inhibition balance towards inhibition as measured using electroencephalography (EEG)?

Secondary research questions are:

• Compared to placebo, does high-dose Vitamin B6 supplementation reduce symptoms of depression and anxiety?
• Do individuals with lower Vitamin B6 levels at baseline, as measured in blood plasma, show a larger effect of high dose Vitamin B6 on the EEG measures or symptoms?
• Compared to placebo, does high-dose Vitamin B6 intervention lead to an increase in hand grip strength? This is a possibility suggested to us by our prvious finding of reduced self reported 'postural disorder' by Vitamin B6 (Field et al., 2024), and by existing literature about the role of Vitamin B6 in muscle function.

Inclusion Criteria:

• Over 18 years of age and under 41
• Mild to moderate anxiety and/or depression
• Normal or corrected to normal vision

Exclusion Criteria:

• not taking daily dietary supplement containing >2 mg Vitamin B6
• not taking medication that is a GABA agaonist (our team will check this with you)
• not be pregnant
• no medical history of epilepsy
• no medical history of peripheral neuropathy
• not taking the antibiotic Seromycin (prescribed for tuberclosis or urinary tract infection)
• no history of brain injury or recent concussion