Blueberries may protect muscles from exercise damage
By Stephen Daniells, 02-Apr-2010
Antioxidant-rich extracts of blueberries may counter the detrimental effect of excessive exercise, according to new results from a new study from New Zealand.
Damage to muscle cells exposed to oxidative stress was significantly reduced when also exposed to doses of blueberry fruit extracts, according to findings published in Molecular Nutrition & Food Research.
“In our study blueberry fruits were suggested as good candidates to combat muscle oxidative damage although further investigations especially at an in vivo level are needed,” wrote the researchers, led by Dr Roger Hurst from New Zealand Institute for Plant and Food Research. Blueberries, nature's only 'blue' food, are a rich source of polyphenols, potent antioxidants that include phenolics acids, tannins, flavonols and anthocyanins.
The berries are said to have a number of positive health effects, including cholesterol reduction, and prevention against some cancers and neurodegenerative diseases such as Alzheimer's. The popularity of the berry has increased in recent years with the publication of more science supporting its health benefits, and an overall consumer move towards 'superfruits' and all things 'antioxidant'.
Potential with perspective
While the new study supports a potential role for improved muscle health, the researchers note the limitations of their in vitro approach, particularly in relation to how this translates to effects in vivo. “Much further research using human intervention studies is warranted to fully understand the implication of the findings reported here with our in vitro evaluations,” wrote the researchers. “Bioavailability concerns also make it difficult to evaluate if the doses used in this and many other published in vitro studies are appropriate.”
Dr Hurst and his co-workers used developing skeletal muscle fibres, also known as myotubes, and exposed them to various concentrations of fruit extracts, as well as a calcium compound known to induce stress as occurs in exercising muscle (calcium ionophore), or a compound known to induce oxidative stress (hydrogen peroxide). Results showed that the blueberry extract protected the muscle fibres in a dose-dependent manner. Further analysis of the extract indicated that the active compounds could be malvidin galactoside and malvidin glucoside, said the researchers. “These in vitro data support the concept that blueberry fruits or derived foods rich in malvidin glycosides may be beneficial in alleviating muscle damage caused by oxidative stress,” wrote Dr Hurst and his co-workers.
From Petri dish to marathon runner
“Although it is difficult to deduce the biological significance of the data presented here from in vitro studies, one may speculate that consumption of blueberry fruit polyphenolics and particularly malvidin glycosides may be beneficial in alleviating the damaging consequences of oxidative stress in muscle tissue,” wrote Dr Hurst and his co-workers. “Our data further endorse that more research in the action of blueberry fruit polyphenolics and muscle function is warranted. Detailed research, especially utilizing human intervention trials may provide the robust evidence required to support the use of blueberry fruit polyphenolics in functional foods and/or sports supplements,” they concluded.
Source: Molecular Nutrition & Food Research, Volume 54 Issue 3, Pages 353-363, doi: 10.1002/mnfr.200900094
“Blueberry fruit polyphenolics suppress oxidative stress-induced skeletal muscle cell damage in vitro”
Authors: R.D. Hurst, R.W. Wells, S.M. Hurst, T.K. McGhie, J.M. Cooney, D.J. Jensen