I would argue that recovery drinks and protein powders count as supplements, which I'm guessing the majority of serious triathletes use. Yes, but for the most part the effectiveness of these drinks has been debunked, and athletes fare just as well eating whole natural foods.*
A must read for all triathletes and endurance sports athletes is Christie Aschwandan's "Good to Go" -
https://www.amazon.com/...574289885&sr=8-1 which get' s into the murky and questionable science and business of Recovery - which very quickly has become a world wide multi $billion industry - and a lot of the stuff is BS or Snake Oil!
*I Emceed the Training Peaks annual Coaches Conference back in September, where Christie was one of the featured speakers and in the Q & A session that followed her talk, this question of post training/racing nutrition came up - just eat whole natural foods, was her answer, and don't get all stressed out about it all!
Steve Fleck @stevefleck | Blog