Can kiwifruit ease exercise-induced stress?

Kiwifruit may help combat a female stress response to exercise that's linked to menstrual dysfunction, infertility and osteoporosis later in life. Photo / File

Kiwifruit may help combat a female stress response to exercise that's linked to menstrual dysfunction, infertility and osteoporosis later in life.

Scientists have begun investigating whether the vitamin C-rich food might ease exercise-induced stress in women, and were seeking participants for their study.

"Several supplements are known for their beneficial effects on immunity and exercise-induced stress, most notably antioxidants such as vitamin C," said study leader Dr Noha Nasef, of Massey University-based Riddet Institute Centre of Research Excellence.

"However, little attention has been paid to whole foods rich in vitamin C, such as kiwifruit."

The first links made between food and health had come from observations of communities with specific dietary patterns associated with a reduced risk of disease.

"From these observations, researchers began to focus on isolating and testing the food-derived compounds from the natural food instead of looking at the food as a whole," she said.

This resulted in many studies showing inconclusive and sometimes negative results.

"To better understand the link between food and health we need to study the natural food as a whole."

How locally-grown, antioxidant-rich whole foods might help alleviate stress and immune response to exercise was largely unknown.

What was known, Nasef said, was that exercise could produce stress markers such as cortisol - and specific to gender.

"We also know that women, particularly athletes, suffer long-term consequences of exercise like osteoporosis and menstrual dysfunction, and we think this is linked to the stress response," she said.

"Vitamin C is known to reduce the stress response after exercise and so what we want to determine is whether vitamin C works better when it is eaten as a natural food like kiwifruit."

Her research team was looking for study participants and need 12 healthy active women living in Auckland, aged over 18, with a regular menstrual cycle.

Nasef said taking part in the research was a great opportunity for people to learn about themselves, such as their fitness and they will also be provided with a body composition test for free.

Participants would be asked to come to the research unit five times.

The first visit involved completing questionnaires about their medical history and physical activity, a body composition test and their height, weight and blood pressure would be measured.

Participants will also complete a maximal exercise test, which was the gold standard for measuring cardiovascular endurance.

The other visits involved participants eating a study meal that contained kiwifruit or vitamin C, providing saliva samples and performing a 30-minute exercise on a cycle ergometer.

Women keen to take part can contact the researchers at goldkiwistudy@gmail.com.