Ribose, a 5-carbon sugar, is useful in stimulating energy production in mitochondria when the usual energy paths are exhausted. Ribose is marginally sweet to the taste, and not sweet at all when compared to sucrose (table sugar). Forward-looking cardiac physicians have found that ribose can restore human energy levels when the normal pathways are exhausted due to cardiac malfunction. Please see the book by Dr Stephen Sinatra Sinatra MD, "Metabolic Cardiology", 2011. For wisest use, see the reference. It is my understanding that Ribose works on the cellular level, facilitating aspects of the Krebs cycle.