This article introduces a special issue of Biogerontology, for which a number of international experts who are still active or have been active in research on the effects of dietary restriction (DR) were asked to answer the following question. Do you think that DR can increase longevity in all species, particularly in human beings? Twelve scientists responded with their opinion articles of which roughly half of them taking the position that yes, DR can be applicable to human beings, while the other half arguing for the inapplicability of DR to humans. The conclusions of these learned opinions are summarized here.