Personally I dont think you can achieve optimal nutrition levels without supplementation on ANY diet let alone a vegan one. The soil is too depleted from generations of farming and most of our food is laced with toxins increasing our need for antioxidants exponentially.
Its been proven without a doubt by tens of thousands of individual case studies that heart disease is totally reversible and preventable yet its the number 1 killer. Its all derived from lack of vitamin C, lysine and proline. Unfortunately humans dont produce their own vitamin C like animals do and our exposure to toxins make the paltry amount most people get inadequate for protection.
So just thinking vitamin C alone with say an optimal MINIMUM dose of 6 GRAMS a day to prevent heart disease I would like to hear from anyone who consistantly gets that daily from food alone.