A new study found eating more than five servings of fruits and vegetables per day does not provide additional benefits in reducing the risk of premature death, contradicting an earlier study that proposed to increase consumption to seven-portions-a-day for optimal results.

The five-a-day portion suggestion came after a recommendation submitted by the World Health Organization (WHO), which urged citizens to consume a minimum of 400g of fruits and vegetables a day, excluding potatoes and other starchy foods.

Increased consumption of fruits and vegetables is vital for maintaining a healthy diet and preventing chronic diseases. The five-a-day program aims to reduce premature death caused by cardiovascular disease and cancer, which in turn improves health and prolongs lives.

A study published in April 2014 by the University College of London recommended doubling the original suggestion, adding more vegetables than fruits to diets in hopes of lowering the risk of premature death by up to 42 percent. The current five-a-day cuts premature death risk by only 25 percent.

"The clear message here is that the more fruit and vegetables you eat, the less likely you are to die at any age. My advice would be however much you are eating now, eat more," said Dr Oyinyola Oyebode, lead researcher from the UCL department of epidemiology and public health, at the time.

But now, new pieces of information might render these findings moot points. Researchers from Harvard School of Public Health and Shandong University in China studied the data of 833,000 people, of whom 56,000 died during the 4.6 to 2 years of a follow-up period. Their results revealed that premature death risk is reduced by five servings, but significant changes did not go beyond that number.

"This analysis provides further evidence that a higher consumption of fruit and vegetables is associated with a lower risk of all-cause mortality, particularly cardiovascular mortality," said the team, led by Prof Frank Hu, of Harvard School of Public Health, in Boston, to BBC News. "There was a threshold around five servings of fruit and vegetables a day, after which the risk of all cause mortality did not reduce further."

The study was published in the July 29 issue of the British Medical Journal.