Endothelial dysfunction is common in both Long COVID and ME CFS and has been linked to symptoms like fatigue, chest pain, and brain fog. Research suggests that certain supplementslike L arginine, CoQ10, curcumin, and Acetyl L Carnitine, 500 mg, 200 Quick Release Capsules Acetyl L Carnitine C9H17NO4 CID 7045767 PubChem Acetyl L Carnitine NOW Foods Acetyl L Carnitine, Cognitive Support, Vegetarian Supplement, 500 mg, 100 Capsules Walmart.com Acetyl L Carnitine Supplement (ALCAR) 500 mg Superior Labs