Neanderthals present an enigma for which there is no consensus about their cognitive and behavioral capacities compared to those of anatomically modern humans. With regards to nutrition, Neanderthals are commonly presented as top carnivores based largely on analyses of the organic fraction of their bones. Here we consider their wide geographical and temporal range, which stretched from the Levant to northern Europe, and eastward to Iraq in both glacial and interglacial periods. The resultant variation in climate and ecology produced significant variation in their plant and animal dietary options. Concomitantly, their energy requirements would also have varied in association. Recognizing these constraints, we consider the physical evidence for diet including associated floral and faunal assemblages, starch grains and plant phytoliths (plant silica bodies) recovered from Neanderthal dental plaque, tooth enamel microwear, and other archaeological data. We also re-evaluate the bone composition data using comparative data from modern human sites. We conclude that Neanderthal subsistence strategies varied with their local environments and included various combinations of plant and animal foods throughout their range. Like modern humans, Neanderthals selected foods that are relatively high in protein from both plant and animal sources.