Nutritional supplements of vitamins, minerals and other healthy ingredients can help people through the stress of earthquakes and their aftermath, according to a New Zealand study.

"Natural disasters such as earthquakes expose whole communities to prolonged, severe distress and trauma. While in the long-term many people display resilience to such stress, almost all may be adversely affected in the short-term," Canterbury University Associate Professor Neville Blampied said in a statement Thursday.

A minority of survivors up to 30 percent in some disasters could experience long-term adverse consequences, Blampied said.

The stress from a disaster affected individuals, families, community groups, and local and regional organizations and institutions, with stress at one level interacting with stress and distress at other levels.

"The series of catastrophic earthquakes that occurred in Christchurch last year and in 2010 provided us with an opportunity to study the impact of nutritional supplements on resilience," he said.

An initial study of 33 adults with a pre-quake diagnosis of attention-deficit hyperactivity disorder (ADHD) and baseline measures of depression, anxiety, and stress found about half of them were taking a nutritional supplement at the time of the Sept. 4, 2010, earthquake.

"Those taking the supplement showed reduced levels of anxiety, depression, and stress in the immediate post-quake period."

A second study of 78 people two months after the Feb. 22 earthquake, which killed 185 people last year, found those taking nutritional supplements showed significant reductions in stress, anxiety, and trauma symptoms over the trial.

The supplements contained 14 vitamins, 16 minerals, three amino acids and three antioxidants, which had been shown in other international studies to benefit bipolar disorder, autism and ADHD symptoms.