In a recent study published in Human Psychopharmacology: Clinical and Experimental, researchers reported that vitamin B6 supplementation reduced anxiety.
Study: High-dose vitamin B6 supplementation reduces anxiety and strengthens suppression of the visual environment. Image credit: Tatjana Baibakova/Shutterstock
B vitamins play a vital role in cellular metabolic processes essential for brain and nervous system function, including those that help maintain the balance between neuronal excitation and inhibition. A balance toward arousal has been implicated in multiple neuropsychiatric disorders, including depression and anxiety. As such, it has been suggested that supplementation with high doses of vitamin B could effectively augment the remarkable behavioral effects of inhibition.
In one study, subjects were supplemented with Marmite, rich in vitamin B, and steady-state visual evoked potentials (SSVEPs) were measured. They observed reduced SSVEP amplitudes after supplementation, implying increased neuronal inhibition or decreased excitation. The study mentioned the established role of vitamin B6 in the synthesis of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter. However, other mechanisms of action could not be ruled out, given that marmite is rich in B12 and other B vitamins.
About the study
In the present study, researchers investigated the effects of high-dose vitamin B6 or B12 supplementation on anxiety and depression. The findings presented here are pooled results from double-blind, placebo-controlled trials conducted over five years. Participants were a general adult population (primarily students) recruited in exchange for course credit through advertisements, social media, and word of mouth.
Participants were randomized to receive vitamin B6/B12 or lactose placebo tablets. Individuals were excluded if they were diabetic, lactose intolerant, epileptic, or using medications that interfere with the absorption of vitamin B. Vitamin B6 tablets contained 100 mg of B6 as pyroxidine hydrochloride, and B12 tablets had 1000 μg of B12 as methylcobalamin; doses far exceeded the Recommended Daily Allowance (RDA). Participants were asked to take one pill with food daily for 30 to 35 days.
Outcome measures were 1) detection of adult anxiety-related disorders (SCAARED) [for anxiety]2) Mood and Feelings Questionnaire (MFQ) – long version [depression]3) sensitivity to visual contrast and surround suppression [the ability to detect low-contrast visual targets in the presence/absence of a suppressive background pattern]4) binocular rivalry reversal rate and 5) touch battery test [tactile sensory processing battery].
discoveries
The study included 478 participants, mostly women (381), aged between 18 and 58. Analysis of variance (ANOVA) of the SCAARED data from the B6 and placebo cohorts revealed a significant decrease in post-test anxiety, primarily driven by the reduction in anxiety among B6. group subjects The minor reduction in anxiety in the placebo group was insignificant. ANOVA of the B12 and placebo groups revealed a significant decrease in post-test anxiety, primarily driven by a decrease in anxiety among participants in the B12 group.
The B6 group also had significantly lower post-test scores on the generalized anxiety disorder (GAD) and social anxiety (SA) subscales of the SCAARED. Cohort B12 had a significant post-test reduction on the separation anxiety subscale (SEP). In contrast, no significant changes were observed in the placebo group.
ANOVA comparing MFQ group B6 and placebo data showed no uniform direction of change in post-test depression. In contrast, depression scores were more likely to decrease after the test in the B6 group, but increase in the placebo group; moreover, this approached statistical significance. However, t-tests comparing pretest and posttest scores did not reveal such significant changes. ANOVA of the B12 and placebo cohort data showed no significant changes, and the t-test of baseline and post-test scores for the B12 group was insignificant.
A stronger surround suppression effect was observed in the B6 cohort, reflecting a significant interaction between treatment and the absence/presence of the suppressive surround. Follow-up t-tests revealed a significant difference in the minimum detectable contrast level between the two cohorts when surround suppression was present and not when it was absent.
In contrast, contrast thresholds were higher in the B12 group than in the placebo cohort, regardless of surround suppression. However, the effect was marginally greater when the environment was present. In the rate of reversal of binocular rivalry, there were no significant differences between either vitamin group and the placebo cohort. Similarly, the two vitamin groups were not significantly different from the placebo group on any measure of the tactile battery test.
Conclusions
The results suggested that vitamin B6 supplementation influenced the balance between neuronal inhibition and excitation. B6 supplementation amplified visual contrast thresholds only in the presence of a suppressive environment. Specifically, this indicated increased neuronal inhibition by higher GABA levels, given that the effect of surround suppression on contrast thresholds is caused in part by inhibitory GABAergic interneurons.
B6 supplementation also reduced self-reported anxiety symptoms. Elevated GABA levels could explain the observed decrease in anxiety. In contrast, B6 supplementation had no apparent effect on other outcome measures (depression, binocular rivalry, and tactile battery tests). Conversely, the team found no apparent effects of B12 supplementation on the outcome measures, although trends suggested lower anxiety and higher visual contrast thresholds.
In conclusion, the study showed that high-dose vitamin B6 supplementation could influence anxiety and observed that the vitamin also increased surrounding suppression of visual contrast detection. Additionally, measuring the effects of other micronutrients on these outcome measures could help identify micronutrients that could be combined and tested as a treatment for anxiety and depression.