Study explores neuroprotective effect of polyphenols in cyclists

By Olivia Haslam

- Last updated on GMT

© GettyImages / PonyWang
© GettyImages / PonyWang

Related tags Polyphenols Antioxidant cycling athletic performance Pollution

Consuming a polyphenol-rich supplement may boost brain-derived neurotrophic factor (BDNF) levels in healthy cyclists exercising in poor air quality, according to a new study.

Writing in the journal Nutrients​, researchers from the University of Auckland and The Eastern Institute of Technology investigated the effects of supplementation with either a phytonutrient blend or placebo in 10 male cyclists following high-intensity interval exercise performed during ozone exposure. 

“Serum BDNF levels increased following an acute bout of high-intensity exercise in an ozone-polluted environment," they wrote. “In addition, supplementation with an anthocyanin-rich supplement providing 4.3 mg/kg anthocyanins daily for 7 days resulted in significantly higher BDNF levels post-exercise compared to placebo.” 

The research was funded by the High Value Nutrition (HVN) Ko Ngā Kai Whai Painga National Science Challenge, a 10-year project to grow the science excellence and knowledge in support of food and beverage exports in Aotearoa, New Zealand. The supplement used in the study is manufactured by Ᾱrepa, a cognitive health company that markets brain drinks, shots, capsules and powders "designed and tested by neuroscientists".

Polyphenols, exercise and ozone exposure

Tropospheric ozone, a component of urban air pollution, is generated through photochemical reactions​ involving hydrocarbons, nitrogen oxides and volatile organic compounds.

A highly reactive oxidizing molecule, it has adverse effects on respiratory​, cardiovascular and central nervous systems​, with links to neurological disorders such as Alzheimer's and Parkinson's disease​, cognitive impairment​, dementia​ and neuroinflammation​.

Previous studies​ have established the neurotoxic effects of ozone exposure, indicating interference with neural physiology, increased lipid peroxidation, reduced dopaminergic neurons, elevated inflammatory markers and accumulation of pathologic proteins. The hippocampus, which is highly sensitive to oxidative effects​, is particularly affected by acute ozone exposure​.

BDNF is found throughout the brain and abundantly in the hippocampus​ and plays a role in neuronal growth, differentiation, neuronal survival, synaptic plasticity​ and memory and learning processes​. Previous research shows that it is influenced by acute exercise​ but appears to be inhibited when exercise is performed in polluted air​.

Polyphenols, including phenolic acids and compounds, have been associated with neuroprotective effects and improved cognitive function​, as well as reduced respiratory inflammation​. They have also been reported to have a beneficial effect on BDNF levels​.

However, the authors noted that controlled trials examining the acute effects of exercise on BDNF with ozone exposure in human subjects are lacking, particularly in the context of using a nutritional intervention to augment the effects. 

“This study therefore investigated whether supplementation with a functional blend of phytonutrients containing blackcurrant, L-theanine, and pine bark extract has a neuroprotective effect and affects cognitive processes following high-intensity interval exercise performed during ozone exposure,” they wrote.

Study details

Participants completed a maximal incremental test and maximal effort 4 km time trial in ambient air.

They then completed two trials in an ozone-polluted environment (0.25 ppm) following seven days of supplementation with either the polyphenol (POLY) blend containing blackcurrant, L-theanine and pine bark extract or a placebo (PL). 

Experimental trials consisted of a three-stage submaximal test followed by a 4 km time trial (TT).

Blood samples were drawn pre- and post-exercise and analyzed for BDNF, interleukin 6 (IL-6), interleukin 10 (IL-10) and tumor necrosis factor (TNF-α). The Stroop test and serial subtraction task were performed before ozone exposure and again after the 4 km TT.

Serum BDNF increased post-exercise, and positive differences were observed post-exercise in the ozone POLY group relative to PL. In addition, plasma IL-6 increased post-exercise, and TNF-α increased post-ozone exposure, however, there were no differences in Stroop or serial subtraction tasks pre- or post-exercise.

“A limitation of the study is the small sample size," the authors noted. "We recommend that future studies be conducted to confirm the findings from the present study and that a larger sample size be recruited.”


Journal: Nutrients
doi: 10.3390/nu16020233
“The Effects of Polyphenol Supplementation on BDNF, Cytokines and Cognition in Trained Male Cyclists following Acute Ozone Exposure during High-Intensity Cycling”
Authors: Lillian Morton et al.

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