The antioxidant effects of green tea polyphenols may protect neurons against the detrimental effects of reactive oxygen species (ROS) and nitric oxide (NO), thereby offering potential benefits for Parkinson’s, says new research from China.

The results are published in the journal Biological Psychiatry.

Parkinson’s disease is a degenerative condition affecting movement and balance in more than one million Americans each year, a figure expected to rise due to ageing populations.

According to background information in the article, the disease is caused by an unrelenting process of cell death affecting the neurons containing pigmented dopamine (DA).

Researchers, led by Baolu Zhao from the Institute of Biophysics, Academia Sinica, Beijing, randomly assigned male Sprague-Dawley rats to one of six groups: control-fed only; control-fed plus 6-OHDA; GTP (150 mg/kg/day) plus 6-OHDA; GTP (450 mg/kg/day) plus 6-OHDA; GTP (150 mg/kg/day) only; GTP (450 mg/kg/day) only.

Green tea contains between 30 and 40 per cent of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3 and 10 per cent. Oolong tea is semi-fermented tea and is somewhere between green and black tea.

The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).

The mix used in this new study contained 50 per cent EGCG, 22 per cent ECG, 18 per cent EGC, and 10 per cent EC (Sichuan Full-green Biology Technology).

Zhao and co-workers report that the green tea polyphenols protected against the toxic effects of 6-OHDA, with the higher dose producing a higher protective effect. Most notable, were the inhibition of increases in ROS and NO levels, and subsequent lipid peroxidation.

“This study shows that, in vivo, GTP partially protected dopaminergic neurons (3.7 times more remaining neuron in GTP-treated than vehicle-treated animals) from 6-OHDA-induced cell death through ROS-NO pathway,” wrote the researchers.

Commenting independently on the study, John Krystal, editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System said: “If green tea consumption can be shown to have meaningful neuroprotective actions in patients, this would be an extremely important advance.”

He added a note of caution however, saying that many health-related benefits have been reported for a wide variety of naturally-occurring substances with many being contradicted by subsequent clinical trials. This is the case with St. John’s Wort and Ginko Biloba, he said.

13-Dec-2007 - Supplements of L-carnitine improved total muscle mass and boosted cognitive performance among a group of centenarians in Italy, reports a new study.

L-Carnitine plays an important role in the production of cellular energy, and is also necessary for the transport of long-chain fatty acids like the omega-3 fatty acids across the membrane of mitochondria, the cell’s power stations.

“Among all the substances whose concentration decreases with age, L-carnitine diminution is fundamentally important, given its function in the production of energy,” explained the authors.

The researchers recruited 66 men and women with an average age of 101 to take part in the study. The subjects, showing signs of fatigue after only slight physical activity, were randomly assigned to receive either the daily L-carnitine supplement (two grams, from Sigma Tau) or placebo for six months.

At the end of the study, the researchers report that the supplementation with L-carnitine was associated with significant reductions in fat mass, compared to placebo. Indeed, the active supplement group lost 1.6 kg of fat mass, while the placebo group gained 0.6 kg.

Total muscle mass in the L-carnitine-supplemented group increased by three kilograms more than the placebo group, report the researchers. Moreover, measurements of fatigue, obtained from a six-minute walking corridor test, decreased after L-carnitine supplementation.

Cognitive performance, measured using the 30-point Mini-Mental State Examination (MMSE), showed increases of 4.1 points for the L-carnitine group, compared to only 0.6 points on average for the placebo group.

Reductions in mental fatigue were also associated with L-carnitine supplementation.

The researchers noted several limitations with their study including using subjects who displayed signs of mild cognitive deficit, having bad eyesight, hearing or who were illiterate. They also note that the subjects were assisted by someone at all times.

Despite such limitations, they concluded that the administration of the supplement did produce benefits related to physical and mental performance among a population at great risk of such declines.

 Consuming antioxidant-rich foods during meals reduces the oxidative stress associated with eating, says a new study that highlights the importance of timing for maximum health benefits.

“We have demonstrated that consumption of certain berries and fruits such as blueberries, mixed grape and kiwifruit, was associated with increased plasma AOC in the postprandial state and consumption of an energy source of macronutrients containing no antioxidants was associated with a decline in plasma AOC,” wrote lead author Ron Prior in the Journal of the American College of Nutrition.

Oxidative stress has been linked to an increased risk of various diseases including cancer, Alzheimer’s, and cardiovascular disease.

“Without further long term clinical studies, one cannot necessarily translate increased plasma AOC into a potential decreased risk of chronic degenerative disease,” stated Prior and co-workers.

In order to determine if the meals containing the different fruit or berries increased the hydrophilic (water-soluble) or lipophilic (fat soluble) antioxidant capacity, measured as Oxygen Radical Absorbance Capacity (ORAC), the researchers conducted five clinical trials with six to ten subjects per experiment. Blood samples from the subjects were taken pre- and post-prandially (before and after the meal).

The researchers report that neither dried plums nor dried plum juice altered either measure of antioxidant activity. Blueberries or mixed grape consumption (12.5 and 8.6 millimole Trolox Equivalents (TE AOC), respectively) with the meal was associated with a increase in hydrophilic AOC. Blueberries also increased the lipophilic AOC.

Cherries, eaten with the meal and providing 4.5 millimoles TE AOC, increased the lipophilic, but not the hydrophilic, AOC.

A control meal, rich in the macronutrients - carbohydrates, protein and fat - consumed without antioxidants was found to result in a decrease of blood AOC, showing an increase in oxidative stress.

“It’s not just what you eat but when you eat it that matters. Phytochemicals in foods have varying degrees of bioavailability and generally are cleared from the blood 2-4 hours after they’re eaten,” said Prior. “Ensuring that your body has a steady supply of antioxidant-rich foods can help combat oxidative stress throughout the day.” 

“It takes about 2.5 servings of antioxidant containing fruits and/or vegetables in a meal… to prevent oxidative stress following the meal.  The more calories you take in the more dietary antioxidants you need,” he added.