Green Tea Could Offer Protection To Sleep Apnoea Sufferers
According to the latest animal research findings from the US, antioxidant-rich extracts from green tea may reduce the effects of oxidative stress caused by breathing problems, such as Obstructive sleep apnoea (OSA), while people are sleeping.
Obstructive sleep apnoea (OSA) occurs when people stop breathing while they are sleeping, often for a minute or more, and this may happen many hundreds of times during a single night's sleep. It is usually caused when the soft tissue in the rear of the throat collapses and closes during sleep. As such, people with this disorder are said to be at risk of oxidative stress and exhibit changes in their brain tissue in areas involved in learning and memory.
Supplements of green tea extracts may counter the cognitive deficits that may occur, suggests a new study with rats.
If the results of the study can be repeated in humans, green tea and its extracts may offer a potential interventional strategy for people with the disorder.
Lead researcher David Gozal, from the University of Louisville, said: "OSA has been increasingly recognized as a serious and frequent health condition with potential long-term morbidities that include learning and psychological disabilities."
Assessing the results
Human OSA was modelled in rats by intermittently depriving the animals of oxygen during 12-hour "night" cycles for 14 days - intermittent hypoxia (IH). The researchers divided the 106 male rats into two groups, with one group assigned to receive drinking water containing green tea polyphenols.
The University of Louisville researchers, in collaboration with scientists from Soroka University Medical Center, then tested the animals for markers of inflammation and oxidative stress, in addition to using a water maze to test their performance in spatial learning and memory tasks.
They found that rats that received the green tea polyphenol (GTP)- supplemented water performed significantly better in a water maze than the rats that drank plain water.
In addition the researchers found that levels of malondialdehyde (MDA), a reactive carbonyl compound and a well-established marker of oxidative stress, were 40 per cent lower in the GTP-supplemented animals.
Commenting on the findings Gozal said: "GTP-[supplemented] rats exposed to IH displayed significantly greater spatial bias for the previous hidden platform position, indicating that GTPs are capable of attenuating IH-induced spatial learning deficits."
"Because oxidative processes underlie neurocognitive deficits associated with IH, the potential therapeutic role of GTP in sleep- disordered breathing deserves further exploration," he added.
Antioxidant activity
The benefits of the green tea extracts were attributed to the antioxidant properties of green tea polyphenols. Gozal explained: "Recent studies have demonstrated the neuroprotective activity of GTP in animal models of neurodegenerative conditions such as Parkinson's and Alzheimer's disease."
Green tea is said to contain over four times the concentration of antioxidant catechins than black tea (green tea leaves that have been oxidized by fermentation), about 70 mg catechins per 100 mL compared to 15 mg per 100 mL for black tea.
The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate, and epicatechin.
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