Age UK's study also revealed 22 per cent of men and nearly one in three women of retirement age suffer with depression.
Louise Morse from Christian charity Pilgrims' Friends Society told Premier why elderly people shouldn't feel downcast.
"It's to know that they have a purpose in old age. God designed old age on purpose - it isn't a mistake," she explained.
"Christians should know this because Ephesians 2:10 makes it clear that we're all individually equipped for the good works that God will bring to us.
There are 1.2m chronically lonely older people in the UK, so Age UK said it's likely we all know or care about someone who feels lonely.
However, the charity said it's not always easy to spot the signs.
Morse told Premier people's age shouldn't make them feel worthless.
"He created aging and older people are as important to God and his purposes for them, as anyone at any age," she added.
"Most people have absorbed ageism unconsciously."
If you need someone to talk to, a listening ear or prayer, then call Premier Lifeline's confidential telephone helpline on 0300 111 0101.
Listen to Louise Morse from Christian charity Pilgrims' Friends Society speaking with Premier's John Pantry and Rosie Wright:
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