Positives

• Long COVID patients on a plant-based pattern commonly report benefits on anxiety, depression, sleep disorders, musculoskeletal pain, and systemic inflammation — the same symptom cluster that dominates Long COVID Current Nutrition Reports.
• One patient with autoimmune disease reported starting a plant-based diet shortly after diagnosis and having no flares or need for medication for over a year and a half, illustrating the kind of inflammation-related benefit other Long COVID patients describe Mayo Clinic Connect.

Negatives

• Studies in ME/CFS, fibromyalgia, and Long COVID reveal abnormalities in carbohydrate metabolism — high-carb plant-based diets can worsen fatigue, brain fog, and cellular energy production for some patients in this population Post-Viral Nutrition.
  
  
• Vegans are 3x more likely than omnivores to have B12 deficiency, and iron and zinc absorption from plant sources is lower than from animal foods — deficiencies that can compound the micronutrient depletion already documented in Long COVID Health Rising.
  
  

Hurdles & Side Effects

• Patients on plant-based diets cannot reliably get B12 from plant foods, so they need either fortified foods two or three times daily totaling at least 3 mcg, a daily supplement of at least 10 mcg, or a weekly 2,000 mcg dose to avoid irreversible deficiency The Vegan Society.
• Strict plant-based eating can backfire if absorption issues, intrinsic-factor variations, or genetic SNPs make B12 supplementation tricky, and several patients reported having to add fish or eggs back when they felt energy slipping despite supplementing Health Rising.