<p>In contrast to the central nutritional problem of overnutrition in younger and middle-aged people, in older and especially very advanced age malnutrition is widespread. A&#xa0;multitude of very different factors can make grocery shopping, meal preparation and adequate nutrition difficult in old age or increase the requirements of energy and nutrients. The resulting nutritional deficiency is associated with functional limitations in the long term and increases the risk of falls, morbidity and complications in the course of the disease. Effective interventions for prevention and treatment are available, from eliminating the underlying causes to supportive measures and parenteral nutrition. The current state of knowledge in this area is summarized in evidence-based, up to date national and international guidelines. As malnutrition is more difficult to compensate for in old age than in younger years, preventive measures are particularly important.</p>