Need more happiness, energy and calm in your life? A new study suggests it could be as easy as adding more fruits and vegetables to your diet.

After analyzing the food diaries of 281 young adults for 21 days, researchers at the University of Otago in New Zealand say they found a day-to-day relationship between those who reported a higher fruit and vegetable consumption and positive mood.

"On days when people ate more fruits and vegetables, they reported feeling calmer, happier and more energetic than they normally did," said lead author Dr. Tamlin Conner in a statement.

Furthermore, researchers point out that eating more fruits and veggies actually predicted improvements in positive mood the next day, suggesting that healthy eating has a direct impact on mental well-being.

The study was published in the British Journal of Health Psychology on January 24.

Meanwhile, like another study published before it out of the University of Warwick in England, the Kiwi scientists said that young people need to eat seven to eight servings of fruits and vegetables a day to notice a meaningful, positive change.

Similarly, the magic number provided by British scientists in their study was seven -- that is, mental well-being peaked among those who ate seven portions of fruits and vegetables a day.

To achieve this food goal, Conner suggests filling up half your plate with vegetables at each meal and snacking on whole fruit like apples.