Study: Green Tea Lowers Cholesterol
GREEN TEA LOWERS CHOLESTEROL
Researchers have completed a comprehensive meta-analysis and found that drinking green tea or taking green tea extract lowered blood levels of total cholesterol, reduced levels of low-density-lipoprotein (LDL or bad) cholesterol, but did not have any effect on levels of high-density-lipoprotein (HDL or good) cholesterol. LDL cholesterol is often referred to by the media as bad cholesterol because some studies have associated higher levels of these fat particles in the blood with health problems and cardiovascular disease.
The effect of green tea on cholesterol has been controversial. The combined results of 14 trials involving a total of 1,136 test subjects showed an average reduction in total cholesterol of 7.20 mg/dL, and an average reduction in LDL cholesterol of 2.19 mg/dL, both of which are considered statistically significant.
This study was released June 29, 2011 by the American Journal of Clinical Nutrition and will appear in a future print issue. It is accessible online now at http://bit.ly/l4mYEW to subscribers or those who pay the access fee.
Reference:
Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trials Am J Clin Nutr 2011 ajcn.010926; First published online June 29, 2011.
Study Shows Green Tea Extract Boosts Memory
Daily supplements of a green tea extract may boost mental al
ertness and enhance memory, according to a randomized, double-blind, placebo-controlled study from Korea.
A combination of a green tea extract with L-theanine was associated with improvements in immediate and delayed recall, and general memory, according to findings published in the Journal of Medicinal Foods.
“As a natural ingredient with a long history of consumption, LGNC-07 [ – a combination of green tea extract and L-theanine - ] should be considered as a potential nutraceutical candidate for enhancing cognitive performance,” wrote researchers.
The study was funded by Korea’s LG Household & Health Care, Ltd., which also produced the ingredient used in the study, and provided one of the co-authors for the paper.
Green tea
The majority of science on tea has looked at green tea, with benefits reported for reducing the risk of Alzheimer’s and certain cancers, improving cardiovascular and oral health, as well as aiding in weight management.
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, epicatechin gallate, and epicatechin.
The success has translated into a booming extract market, valued at a around $44m (€29.7m), according to recent report from Frost & Sullivan. The market is expected to grow by more than 13 per cent over the next seven years. Key players include DSM, Taiyo, and Tate & Lyle. Innovation in delivery has also seen companies like Maxx Performance release an encapsulated green tea extract for bakery applications.
L-theanine, an amino acid found in tea leaves, is thought to help reduce stress, promote relaxation and improve the quality of sleep. L-theanine is found in tea leaves in low concentrations (less than 2 percent), which means that effective dosage levels (of 100 – 200mg/day) cannot be delivered from drinking tea.
Study details
Ninety-one participants with mild cognitive impairment – a risk factor for Alzheimer’s disease – were recruited and randomly assigned to receive either 1,680 mg of the green tea extract-L-theanine combination (LGNC-07) or placebo (maltodextrin plus lactose) for 16 weeks.
A number of tests were used to assess memory and attention. Results showed that volunteers receiving the green tea supplement exhibited improvements in memory: ‘Marginal’ improvements were observed with regards to the delay in recognition, and ‘significant’ increases in memory regarding recall of word reading.
Electroencephalograms (EEG) were recorded in 24 volunteers, and these scans showed improvements in indicators of mental alertness in specific parts of the brain.
The Health Benefits of Green Tea
Did you know?
Tea lovers’ beverage of choice lowers blood pressure.
Drinking just a half-cup of green or oolong tea per day reduces a person’s risk of high blood pressure by almost 50%.
People who drink at least two and a half cups per day reduce their risk even more!
Risk is reduced even if tea drinkers have known risk factors for high blood pressure, such as high sodium intake.
Green Tea & Depression
Green Tea May Combat Depression in Elderly
Drinking frequent cups of green tea is linked to a lower incidence of depressive symptoms in elderly people, say Japanese researchers.
A study published in the American Journal of Clinical Nutrition focused on 1,058 elderly Japanese individuals 70 years of age plus with the prevalence of mild and severe and severe depressive symptoms said the authors.
The authors maintain that only a few studies have investigated the relationship between green tea consumption and mental health, while there appear to be few studies assessing the relationship between green tea drinking and depressive symptoms.
According to the team led by Atsushi Hozawa, depression in the elderly is highly prevalent and can increase the risk of medical illnesses, worsen the outcome of other medical illnesses, and may increase mortality.
Growing problem
World Health Organization (WHO) forecasts that within 20 years more people will be affected by depression than any other health problem; it ranks depression as the leading cause of disability worldwide, with around 120 million people affected.
Findings show that the occurrence of depressive symptoms was 44% lower for participants who drank 4+ cups of green tea/day compared to those who drank less than one, after results were adjusted for factors such as age, sex, disease history, BMI, alcohol consumption, cigarette smoking, diet, and other factors.
The authors state that their study is rather limited in scale and a larger population study that uses a standardized comprehensive structured diagnostic interview is required to confirm the effect of green tea consumption on depressive symptoms.
Mental stress
A previous study also led by the Hozawa found that drinking 5 cups of green tea/day may reduce the incidence of psychological distress by 20%.
Green tea consumption was said to improve psychological well-being in a study population of 42,093 Japanese individuals of which 6.6% suffered from psychological stress.
Relaxation benefits
The potential of green tea offers more than its well-known role as an antioxidant.
According to research from Unilever, green tea contains L-theanine, which is said to relax the brain.
Consumption of 50mg of L-theanine (equivalent of 2-3 cups of green tea) stimulates the alpha-brain waves associated with relaxation. By increasing the frequency of these brain waves, the beta-brain waves associated with tension are decreased.
Consumer awareness of the benefits of green tea and green tea extracts continues to rise with growing numbers of studies, from 430 papers in 2000 to almost 1500 in 2003, reporting benefits of the main compounds, catechins.
Source: American Journal of Clinical Nutrition
Published online ahead of print: doi: 10.3945/ajcn.2009.28216
Title: Green tea consumption is associated with depressive symptoms in the elderly
Authors: K Niu, A Hozawa, S Kuriyama, S Ebihara, H Guo, N Nakaya, K Matsuda, H Takahashi, Y Masamune, M Asada, S Sasaki, H Arai, S Awata, R Nagatomi, and I Tsuji