You ask the question of safety and effectiveness for a particular type of nutritional intervention.
There are several questions here: is it effective, is it safe, is it effective and safe for the type of individual with whom I am working, and is it safe and effective for the specific individual with whom I am working.
People who work in fitness will have a variety of opinions on the safety and efficacy of various supplements, nutritional strategies, diets, fasts, juicing, etc…. But what they use themselves, and what they are ready to recommend professionally are not always the same. I suspect a majority of people, especially if they are not engaged in selling the products, would be for a whole, well balanced diet first, in any case.
The question you did not ask, but which will be part of every answer you get, is whether it is within the scope of practice of someone who is not a nutritionist to answer this safely and effectively. Suppose you advise this person to use a product like this and they have an allergy to something in the product? Or they use it in a way that makes them ill? A question like that rarely has a hard and fast answer, and must be based on a good knowledge of nutrition, as well as of the health history of the individual.
Aside from the most important questions of staying within our professional scope of practice, and not wishing to cause harm, but to promote wellness there is one other million dollar question: Will your insurance cover you if you answer this and something unexpected happens?