However, false advertising claims are handled by the FTC. I suggest you talk to them before the FDA.
edit: For a court case to be effective the plaintiff has to prove that the product does not work; the burden of proof is not on the manufacturer, according to FDA regulations. Depending on wording this could require a long testing period with many people for a judge to take it seriously.
General Mills got the smack down from the FDA for claiming that Cheerios lowered your cholesterol. [1]
[1]http://www.fda.gov/iceci/enforcementactions/warningletters/u...
These claims indicate that Cheerios® is intended for use in lowering cholesterol, and therefore in preventing, mitigating, and treating the disease hypercholesterolemia. Additionally, the claims indicate that Cheerios® is intended for use in the treatment, mitigation, and prevention of coronary heart disease through, lowering total and "bad" (LDL) cholesterol. Elevated levels of total and LDL cholesterol are a risk factor for coronary heart disease and can be a sign of coronary heart disease. Because of these intended uses, the product is a drug within the meaning of section 201(g)(1)(B) of the Act [21 U.S.C. § 321 (g)P)(B)]. The product is also a new drug under section 201(p) of the Act [21 U.S.C. § 321(p)] because it is not generally recognized as safe and effective for use in preventing or treating hypercholesterolemia or coronary heart disease. Therefore,under section 505(a) of the Act [21 U.S.C. § 355(a)], it may not be legally marketed with the above claims in the United States without an approved new drug application.
Isn't that the intent? Rob Rhinehart (creator) lived for a period of one month eating Soylent and nothing else. My understanding is that Soylent is intended to be a meal replacement, not a supplement of some kind.
While I'd love for this to be a safe, reliable option, and might even try it as a replacement for some proportion of meals if/when it becomes more widely available, their marketing claims far exceeds what they have evidence for so far.