The known effects of protein poisoning and the safe limits of protein intake are described. Attention is drawn to the need for consideration of the implications of the debilitating and potentially serious consequences of excess protein consumption when reconstructing palaeodiets and subsistence strategies. In spite of the ready availability of a stable source of protein-rich marine foods, the limits to protein utilization for energy (20-50% of daily needs) would have forced coastal hunter-gatherers to provide for a nutritional balance between protein and fat-or carbohydrate-rich sources of food. Current hypotheses concerning coastal palaeodiets are based on excessive protein intake and do not deal adequately with this problem. The concept of a largely protein marine diet as an economic strategy over more than a few days is questioned. -- AATA