A study by the National Council on Ageing and Older People has found that the vast majority (73%) of older people have strong family and community networks and do not feel isolated.
However, the report estimates that a significant minority of older people (11%) - some 50,000 - have minimal social contacts and experience loneliness and isolation.
This group are also more likely to be in poor health and as a result, are more vulnerable in times of illness or personal crisis.
Those most at risk include single or widowed women, those aged over 80 years and from less prosperous backgrounds.
Older people living in rented accommodation or with relatives in rural areas also experience higher levels of loneliness.
The council identified poor health and lack of transport as key factors which contribute to social isolation. Almost 700 older people were interviewed by telephone for the study.
