Who doesn't want to be happy? Apparently, attaining happiness is as easy as eating more fruits and vegetables, according to a new study.

Dr. Redzo Mujcic from the University of Queensland's School of Pharmacy studied over 12,000 adults in Australia to determine how eating at least eight portions of fruits and vegetables each day improves mental well-being.

Eating a healthful diet has long been associated with improving physical health but not much has been done to show its effects on mental health.

For the study, Mujcic assessed the subjects' choices of fruits and vegetables in relation to their vitality, stress and satisfaction levels, which are indicators of mental health. His study employed richer methods of examining people, observing individuals several times over multiple periods.

In "Are fruit and vegetables good for our mental and physical health? Panel data evidence from Australia," Mujcic presents how consuming fruits and vegetables has a positive and independent influence on self-reported measures of mental and physical well-being.

"[But] while the daily intake of both fruit and vegetables is found to matter for the above health measures, the sole consumption of fruit (as opposed to vegetables) is estimated to have more profound effects on distinct indicators of emotional well-being, such as the overall mental health and psychological distress scores (peaking at about 4-5 daily portions)," Mujcic shared [pdf].

"Significant gender differences are also apparent in life satisfaction and self-assessed health ratings, with the estimated fruit and vegetable gradients being stronger for female than male respondents," he added.

The study, Mujcic claims, is also supported by research from international teams. One is a study from the United Kingdom and another from New Zealand, both of which showed that people are happiest when they consume eight portions of fruits and vegetables every day.

Eating nutritious foods, which normally includes fruits and vegetables regularly, has been recommended by doctors for years. However, fast-paced lifestyles don't exactly make it easy to add fruits and vegetables to meals. Many of us are just not used to eating fruits and vegetables daily.

The Harvard Medical School's Family Health Guide suggests easing into it. Start by eating one more fruit or vegetable in a day. After getting used to that, add another.

The technique is to keep going until the recommended number for optimum mental health is achieved. Don't forget to add variety as well to ensure you're getting a good mix of nutrients from fruits and vegetables.