Shieff, a former two-time World Free Running champion, was a vocal vegan for many years until he ditched the lifestyle for good early this year, blaming the diet for a slew of health issues. Some commentators blamed Shieff's more extreme activities - including a 35-day unsupervised water fast and drinking his own urine for any medical problems. Shieff has denied this, saying he did these things in a bid to improve his health.
Despite the controversy this has generated within the vegan community, Shieff remains popular among many fans, and a number of brands including Raw Sport - with whom he has just partnered.
The athlete announced the partnership on Instagram, saying: "Pumped to announce I am officially a @rawsportofficial Athlete. I have been using these guys' products for years ever since I first got in to health foods.
"Raw Sport's pine pollen is probably my most used product and even though I'm not vegan, I still fully advocate the use of plant-based protein powders over all others when it comes to meal replacing or supplementing. (you still gotta eat right for your type outside of this though)
"They are a legit team who care about health and all do sport to a high level themselves...They also care about providing the highest quality product and source the finest ingredients for everything they do...I understand the stand that they are taking by supporting me and truly admire their openness and integrity to still do so. Stoked to be on the team."
Raw Sport founder Dean Howell, who was a professional footballer for more than 15 years, told Plant Based News: "Tim Sheiff being an ambassador of Raw Sport is an interesting combination, due to him turning vegan and then back into non-vegan. Ultimately, Tim is looking for a healthy lifestyle, and he didn't quite find it on vegan diet.
"We see this a lot, and its been my goal from day one to concentrate on health, well being, and performance through plant-based nutrition. Just because you are vegan, it doesn't mean you are healthy. We created Rawsport to help educate and inspire anyone looking for gains in both health, wellness and performance.
"I have known Timothy for a long time and followed his career with interest, he is unquestionably a talented guy, we look forward to supporting him where we can on his health journey."
Howell added that his business has a 'strong purpose', and wants to achieve two major goals. "[The first is to] influence the general public to be more balanced in their day to day diet, move from dairy and animal proteins to plant-based products.
"Until now plant proteins have tasted horrendous, this has been a huge blocker to people moving from dairy products to plant products. From the feedback and growing customer base, RawSport is getting, we are definitely heading in the right direction."
He said the second goal it to raise awareness of vegetarians and vegans to 'incorporate the right nutrition, so they can build on a healthy lifestyle'.
"As a company, we don't sell whey protein, all products must hold a standard and one of those is suitable for vegans," he said. "We test for heavy metals, we are soy-free, dairy-free and non-GMO.
"Raw Sport partners with many professional athletes and celebrities who are turning more and more to a plant-based diet due to the results they see and feel."
Vegan diet is healthy at all stages of life
It should be noted that major dietary organizations agree that a vegan diet can be safe for all stages of life, with the American Academy of Nutrition and Dietetics taking the position that 'appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits for the prevention and treatment of certain diseases'.
"These diets are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood, and for athletes. Plant-based diets are more environmentally sustainable than diets rich in animal products because they use fewer natural resources and are associated with much less environmental damage," it adds.
"Vegetarians and vegans are at reduced risk of certain health conditions, including ischemic heart disease, type 2 diabetes, hypertension, certain types of cancer, and obesity."