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Index of Subjects Hi James, The hummer question is more of physiological than chemical nature. As you already mentioned hummingbird physiology is specialized to the uptake of large amounts of sugar, the only energy source to fuel their high turn-over energy metabolism. Human physiology works different. Nectar and other plant secretions (sap from sapsucker wells) contain foremost water (~80%) and sugars (~20%), along with traces of vitamins, amino acids, fatty acids. The sugar mix consists mainly of sucrose (aka our table sugar), glucose, and fructose in plant species specific ratios, and sucrose is easily split by a single enzyme in glucose and fructose. Those can then directly be fed into the metabolic pathway to produce energy in the form of ATP, the universal energy currency in cell metabolism. Problems for hummers would only arise if their diet would be restrictred to sugarwater only (and nectar for that matter as well). Then they would lack amino acids, fatty acids, vitamins, and other essential nutrients required to build and maintain their bodies. Insects and other prey consumed by hummers are the source for these nutrients as the traces contained in natural nectar are insignificant. Aphids have to process large amounts of plant sap to gather the required amounts of nutrients from it and void the surplus water and sugar collected in the process as honeydew, essentially throwing away tons of energy rich carbohydrates they don't need. Should we add supplements to the sugar water (artifical nectar)) we feed our hummers? No, most of those nutrients have short half life times, i.e. would be gone by the time a hummer consumes the fluid, and in the meantime potentially only promote growth of bacteria in the solution. The almost exclusive source of those nutrients are other elements in the hummer diet than nectar! Ulli
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