According to Mark Lowndes, area manager of mental health charity Changes, diet is not "the be all and end all", but it does play a significant role in preventing depression.
Nearly two thirds of British people do not eat the recommended five portions of fruit and vegetables every day, according to research conducted by Cancer Research UK, and this could be a factor in many people's depression.
"Having the right balance, in terms of nutrition, can help keep you in top form and stop you getting into depression," said Mr Lowndes.
"There are lots and lots of things that can affect people with depression, and nutrition and diet is part of that," he continued.
The expert noted that eating healthy food or taking multivitamins will therefore not cure depression.
"It is a long process, but I believe [diet and nutrition] can have an effect on it," he concluded.
A recent study of 202 depressed adults also found that group-based exercise therapy can be as effective as medication in improving the symptoms of major depression.