The latest indications we have suggest that Einstein was vegetarian only for the last year or so of his life, though he appears to have supported the idea for many years before practising it himself.
“So I am living without fats, without meat, without fish, but am feeling quite well this way. It always seems to me that man was not born to be a carnivore.” — This was from a letter written to Hans Muehsam, and dated March 30, 1954, which was about 1 year before Einstein died. This indicates he adopted a vegetarian diet at the end of his life. Previously, on August3, 1953 Einstein had written the following in a letter to Max Kariel, suggesting that he was still eating meat at that time: “I have always eaten animal flesh with a somewhat guilty conscience.” —- - Einstein Archive 60-058