Can kiwifruit reduce exercise-induced stress in women?

Thursday, August 23, 2018

Can kiwifruit reduce exercise-induced stress in active women?

While exercise as part of a healthy lifestyle can prevent communicable diseases, it can also cause a stress response. In women, the exercise-induced stress response is implicated in menstrual dysfunction, infertility and osteoporosis later in life.

Now Massey University researchers are investigating whether kiwifruit, which is high in vitamin C, can reduce the stress response triggered by exercise in women.

Dr Noha Nasef from the Riddet Institute Centre of Research Excellence is leading the research, alongside Cameron Haswell, Wendy O’Brien, Marsanne Chabert and Associate Professor Ajmol Ali, all from the School of Sport, Exercise and Nutrition, Associate Professor Kay Rutherfurd-Markwick from the School of Health Sciences and Dr Carlene Starck from the Riddet Institute Centre of Research Excellence.

“Several supplements are known for their beneficial effects on immunity and exercise-induced stress, most notably antioxidants such as vitamin C,” Dr Nasef says. “However, little attention has been paid to whole foods rich in vitamin C, such as kiwifruit.”

The first links that have been made between food and health came from observations of communities with specific dietary patterns associated with a reduced risk of disease, Dr Nasef says. “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. 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. In the context of this study, the efficacy of antioxidant-rich whole foods, grown locally in New Zealand, in alleviating the stress and immune response to exercise, is largely unknown.

“We know that exercise can trigger a stress response –Dr Ali and his team have previously shown that exercise increases stress markers such as cortisol in a sex-specific manner. 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. 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,” she says.

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

Dr Nasef says taking part in the research is 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 will get insight into how the latest research in exercise and nutrition is being done, not to mention they will get to eat delicious Sungold kiwifruit.”

Participants will be asked to come to the research unit on five separate occasions. The first visit will involve completing questionnaires about their medical history and physical activity, a body composition test and their height, weight and blood pressure will be measured. Participants will also complete a maximal exercise test, which is the gold standard for measuring cardiovascular endurance.

Visits two to five, which are the main study visits, will involve participants eating a study meal that contains kiwifruit or vitamin C, provide saliva samples and perform a 30-minute exercise on a cycle ergometer.

For more information, please contact the team: goldkiwistudy@gmail.com

The study is being funded by the Massey University Research Fund and the Riddet Institute Centre of Research Excellence.
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