The Adventurers' Guild

As of May 2013, Soylent has been tested by Rhinehart himself and by a handful of volunteers as well as individuals recreating the substance independently at home.[5][13] Modifications to the ingredient list have occurred in response to results incurred in testing, for example: the first version of the formula omitted iron, which caused Rhineheart to report his heart had begun to race.[8] In other early experiments, intentionally induced overdoses of potassium and magnesium gave Rhinehart cardiac arrhythmia and burning sensations.[8] After the early recipe had stabilized, Rhinehart found himself suffering from joint pain due to a sulfur deficiency. Methylsulfonylmethane was added to address this problem.[8][12]

Soylent in its present form may lack some nutrients essential for normal body functioning and/or may fail to provide nutrients in appropriate proportions, potentially causing medical problems if used long-term.[4] The fundamental basis of the assumptions made by Soylent are disputed; with focus on the fact that, because digestion is a complex phenomenon and there is not a simple linear relationship between nutrient ingestion and nutrient absorption, many factors contribute to nutrient absorption in the human body.[14]

With respect to the suitability of the product for general consumption, homemade Soylent is made without the kinds of regulatory safeguards and fine-tunings followed when making accepted artificial diets such as medical food.[1]