Remember that the key difference between a drug and something else is "intended use." Cheerios when advertised as food can't be regulated under the Food, Drug, and Cosmetics Act (FDCA). The same product, if sold as a treatment for cardiovascular disease would need to undergo the drug approval process and approved by the FDA.
This is essentially what the Federal court system has told the FDA regarding regulation of e-cigarettes. If the products are sold with no claims that they can prevent, treat, or mitigate a disease, FDA can only regulate them under the Tobacco Act. If intended to treat the disease of "smoking" (a disease made up by the FDA -- it is not found in any diagnostic manual), then the FDA can regulate the exact same product under the FDCA. The drug version would have to be given a different name to avoid confusion.
Another example of this is the B vitamin Niacin. On pharma company tested it as cholesterol-lowering medication and it has been approved for sale as such under the brand name Niaspan. The vitamin, with the exact same dosage and timed release remains on the market as a supplement. Of course the price is a tad different for the two versions....
