Vitamin B12
Non-negotiable on any vegan diet. 250 µg daily or 2500 µg weekly, cyanocobalamin form. Deficiency mimics depression and fatigue.
Health · Mental wellbeing
Vegan diet and mental health
What the science actually says about plant-based eating, mood, anxiety and cognition — plus the six nutrients that quietly shape how you feel.
The nutrient shortlist for a happier brain
Vitamin D
Aim for 25(OH)D above 30 ng/mL. 1000–2000 IU daily D3 (lichen-derived) covers most latitudes in winter.
Omega-3 (DHA/EPA)
Algae oil 250–500 mg combined DHA+EPA daily. Chia, flax and walnuts alone don't reliably convert to enough DHA.
Iron
Combine legumes and whole grains with vitamin C sources; check ferritin annually. Low iron is a top cause of low mood in menstruating people.
Iodine & zinc
150 µg iodine (iodised salt or a multi) supports thyroid and mood. Zinc from beans, seeds, tempeh keeps neurotransmitters humming.
Enough calories & protein
Under-eating flattens mood fastest. Vegans need slightly more protein per kg — see the calculator below.
The gut–brain connection
About 90% of serotonin is produced in the gut. Diets rich in fibre and polyphenols (fruit, vegetables, legumes, whole grains, nuts) feed a more diverse microbiome, which is linked to lower anxiety and depressive symptoms in randomised trials. Plant-based diets are the most fibre-dense pattern studied — 40–60 g/day is common versus a Western average of 15 g.
40–60g
fibre/day on a whole-food vegan diet
90%
of serotonin made in the gut
−32%
depression risk in high-fibre cohorts
FAQ
Does a vegan diet cause depression?
No. Recent meta-analyses find no consistent link between well-planned plant-based diets and higher depression risk; some cohorts show modest improvements in mood when overall diet quality rises. Symptoms occasionally attributed to “going vegan” usually track under-eating, low B12, low omega-3 or iron deficiency — all fixable with basic planning.
Which nutrients matter most for mood and cognition?
Vitamin B12 (from a supplement), long-chain omega-3s (algae DHA/EPA), iron, iodine, zinc, vitamin D, and enough total calories and protein. Deficiencies in any of these — vegan or not — can flatten mood, memory and energy.
Do I need to eat fish for omega-3s?
No. Algae oil delivers DHA and EPA directly, without the mercury, PCBs or overfishing concerns tied to fish oil. Aim for 250–500 mg combined DHA+EPA per day.
Can a plant-based diet reduce anxiety?
Randomised trials of Mediterranean and plant-forward diets show reductions in anxiety and depressive symptoms, largely mediated by fibre, polyphenols and improved gut microbiome diversity.