Nutrition and recovery are often overlooked when considering a successful training plan. However, I consider them to be as important as the training you do. Scott Jurek, in his book “Eat and Run”, felt that there were benefits to following a vegan diet. If you have ethical or moral reasons then this may inform your decision. There are other athletes who successfully follow a vegan diet and perform very well, but to do so requires a great deal of meticulous planning and preparation. It will increase the challenge (and stress) of training for triathlon if you have much of your time already occupied.
To be successful in sport, your nutrition must help you not just to recover but also to repair muscles and connective tissues. You will need to make sure that you are getting the correct quantity of minerals and vitamins on a regular basis. Nancy Clark, sports nutritionist and author of “Nancy Clark’s Sports Nutrition Guidebook”, suggests that vegans need to eat about 10% more protein than non-vegans, and the challenge is the availability of food. If deficiencies occur it affects basic metabolic functions including brain function and immune system strength, never mind sports performance.
An Ironman triathlete and Kona favourite, Lionel Sanders experimented with a vegan diet prior to Kona 2018 and it proved disastrous for him. Maybe it was the timing in relation to the race, or maybe the challenge of finding and eating the right foods was bigger than he realised when training 25 hours per week. Either way, I would consider this option very carefully before taking the first step. You might even want to think about reducing the stress on your body by cutting back on training while you do so until you adapt to your new eating regime.