The numbers of individuals in prison in countries other than their own has grown significantly in recent years as a result of the increased mobility of people and the marked differences in economic well-being and opportunities between one country and another. The major problem faced by foreign prisoners is one of language. In order to receive the best medical treatment, it is necessary for prisoners to be able to communicate with their doctors and be able to understand them in return. This is especially true in instances of psychiatric treatment. In discipline areas, the need for prisoners to understand the prison rules and the authorities which enforce such rules is obvious. The negative effects of cultural and social deprivation are widely recognized, and the deprivation may be even more severe for the foreign prisoner who has limited opportunity for social intercourse because of a language barrier, and is far from family or friends who might visit. Cultural differences pose a second source of problems for individuals in prisons in countries other than their own. Differences in diet can arise from religious rules, and the radical changes in diet caused by cultural differences in the country in which they are incarcerated can cause health problems.