Monday, March 24, 2014

Green Tea, Coffee May Guard Against Stroke

Megan Brooks
April 03, 2013
Green tea and coffee consumption may help protect against stroke, according to a large Japanese population-based study.
The study showed that people who drank green tea or coffee regularly had about a 20% lower risk for stroke than their peers who seldom drank these beverages.
"This is the first large-scale study to examine the combined effects of both green tea and coffee on stroke risks," Yoshihiro Kokubo, MD, PhD, head of the Department of Preventive Cardiology, National Cerebral and Cardiovascular Center in Osaka, said in a statement.
Their findings were published online March 14 in Stroke.
Inverse Link
The study involved 82,369 Japanese adults aged 45 to 65 years without cardiovascular disease or cancer at baseline who were followed for a mean of 13 years. "Green tea and coffee consumption was assessed by self-administered food-frequency questionnaire at baseline," Dr. Kokubo toldMedscape Medical News.
During more than 1 million person-years of follow-up, the researchers documented 3425 strokes (1964 cerebral infarctions, 1001 intracerebral hemorrhages, and 460 subarachnoid hemorrhages) and 910 coronary heart disease (CHD) events (489 definite myocardial infarctions and 28 sudden cardiac deaths).
In multivariate analysis, higher coffee and green tea consumption were inversely associated with risk for cardiovascular disease (CVD) and stroke.
For example, people who drank at least 1 cup of coffee daily had a 20% lower risk for any stroke (adjusted hazard ratio [aHR], 0.80; 95% confidence interval [CI], 0.72 - 0.90) compared with those who seldom drank coffee.
People who drank 2 to 3 cups of green tea daily had a 14% lower risk for any stroke (aHR, 0.86; 95% CI, 0.78 - 0.95), and those who consumed at least 4 cups had a 20% lower risk (aHR, 0.80; 95% CI, 0.73 - 0.89), compared with those who seldom drank green tea.
The risk reduction for intracerebral hemorrhage was 17% (aHR, 0.83; 95% CI, 0.68 - 1.02) with consumption of at least 1 cup of coffee daily and 23% (aHR, 0.77; 95% CI, 0.63 - 0.92) for 2 cups of green tea daily compared with rare consumption of either beverage.
There was no significant association between coffee and tea consumption and CHD, largely mirroring findings from other studies.
Experts Weigh In
Victoria J. Burley, PhD, senior lecturer in nutritional epidemiology, School of Food Science and Nutrition, University of Leeds, United Kingdom, who wasn't involved in the study, called it "very interesting."
She noted that "both high-fiber foods and these particular beverages may have anti-inflammatory properties. Whole grains, fruit and vegetables, and these beverages are all rich in polyphenols, which appear to have multiple potential actions on markers of CVD risk: blood pressure, glucose homeostasis, lipid metabolism, and so on."
"This appears to be a well-conducted study," Dr. Burley said, "with good power (plenty of cases), with long follow-up and a respectable method of assessing green tea and coffee intake (for these dietary aspects I think an FFQ [food-frequency questionnaire] is likely the best approach)."
She cautioned, however, that the intakes of green tea in this Japanese cohort "far exceed" usual consumption in western populations and that, conversely, intakes of coffee may generally be somewhat lower in Japan.
"The highest coffee intake category was 2-3 cups per day, which is not particularly high. Other studies (eg, conducted in Sweden) have reported elevated CVD risk in people with much higher intakes ( > 7 cups per day), so in setting their highest category this low these study authors may not have been able to pick up evidence of increased CVD risk with greater intakes," Dr. Burley said.
"Overall, it's encouraging data that suggest people who incorporate coffee and green tea in their diet may experience lower CVD risk in later life," she added.
Commenting on the coffee findings, Susanna C. Larsson, PhD, from the Unit of Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden, found it "interesting that such a small amount as 1 cup of coffee per day reduces the risk of stroke by 20% (quite a large reduction in risk)."
"Otherwise, this Japanese study confirms results from studies conducted in the US and Europe showing an inverse association between coffee consumption and stroke risk. This study adds further support that moderate coffee consumption may lower the risk of stroke," said Dr. Larsson, who was not involved in the study.
The study was supported by Grants-in-Aid for Cancer Research and the Third-Term Comprehensive Ten-Year Strategy for Cancer Control from the Ministry of Health, Labor and Welfare of Japan. The authors, Dr. Burley, and Dr. Larsson have disclosed no relevant financial relationships.

Stroke. Published online March 14, 2013. Abstract

Fruit, Tea, and Wine Could Guard Against Type 2 Diabetes

January 20, 2014
A new study in healthy women suggests that consuming high levels of flavonoids, including compounds found in berries, tea, grapes, and wine, could potentially lower the risk of type 2 diabetes.
The study, published in the February issue of the Journal of Nutrition, indicates that greater intake of these dietary compounds is associated with lower insulin resistance and better blood glucose regulation. The researchers, led by Amy Jennings, PhD, from the department of nutrition, University of East Anglia, Norwich, United Kingdom, say their study is one of the first to examine consumption of different flavonoid subclasses and insulin resistance.
"We found that those who consumed plenty of anthocyanins and flavones had lower insulin resistance. So what we are seeing is that people who eat foods rich in these 2 compounds — such as berries, herbs, red grapes, wine — are less likely to develop the disease," said senior author Aedin Cassidy, PhD, also from the department of nutrition, University of East Anglia, in a statement.
Researchers also found that those who ate the most anthocyanins were least likely to suffer chronic inflammation, which is associated with diabetes, obesity, cardiovascular disease, and cancer. And those who consumed the most flavone compounds had improved levels of adiponectin, which helps regulate a number of metabolic processes, including glucose levels, Dr. Cassidy noted.
Importantly, the difference between the highest and lowest intakes of foods containing these compounds was small, consisting of just one portion of grapes or berries or a couple of oranges, say the authors. Also, the effects on insulin that were associated with high consumption of such foods was equivalent to those observed for other lifestyle factors, such as an hour's walk a day or low-fat diet for a year, they noted.
Nevertheless, Dr. Cassidy said it is not yet know exactly how much of one of these compounds is necessary to potentially reduce the risk of type 2 diabetes. "Dose–response trials are needed to ascertain optimal intakes for the potential reduction of type 2 diabetes risk," she and her colleagues stress.
One of the First Large Human Studies of Flavonoid Subclasses
Researchers note that a previous prospective study, published last year in the American Journal of Clinical Nutrition suggested a 15% reduction type 2 diabetes risk by comparing the highest and lowest quintiles of anthocyanin intake. However, the researchers emphasize that their current study is one of the first large-scale human trials to examine all subclasses of these powerful bioactive compounds to see how they might affect insulin resistance, blood glucose regulation, and inflammation.
The cross-sectional study was conducted in almost 2000 women aged 18 to 76 years from the Twins UK registry. Women who had high glucose levels were excluded. Participants completed a 131-item food-frequency questionnaire, from which flavonoid intakes were estimated using a United States Department of Agriculture database.
The researchers looked at the self-reported intake of 6 subclasses of flavonoids: flavanones, anthocyanins, flavan-3-ols, polymeric flavonoids, flavanols, and flavones.
In multivariable analyses, higher anthocyanin and flavone intakes were associated with significantly lower peripheral insulin resistance (homeostasis model assessment of insulin resistance; quintile 5 [Q5] to Q1 = 20.1, P-trend = .04 for anthocyanins and flavones), as a result of a decrease in insulin concentrations (Q5–Q1 = 20.7 mU/mL, P-trend = .02 anthocyanins; Q5–Q1 = 20.5 mU/mL, P-trend = .02 flavones).
Tea was the main source of overall flavonoid intake, with 4 foods contributing more than 10% of anthocyanin intake (grapes, pears, berries, and wine) and 3 foods making up more than 10% of flavone consumption (oranges, wine, and peppers).
Higher anthocyanin intake was also associated with lower C-reactive protein (hs-CRP) levels (Q5–Q1 = 20.3 mg/L, P-trend = .04), whereas those in the highest quintile of flavone intake had improved adiponectin levels (Q5–Q1 = 0.7 mg/L, P-trend = .01).
Higher intakes of both anthocyanins and flavones were associated with improvements in insulin resistance and hs-CRP, the researchers note.
No significant associations were observed for total or other flavonoid subclasses.
Findings Are Clinically Relevant, Easy to Achieve
Although these findings are from cross-sectional data and require confirmation, they are clinically relevant because of the 0.7-mU/mL difference in insulin observed between the top and bottom quintiles of anthocyanin intake, the researchers note.
The difference in anthocyanin intake between the top and bottom quintiles was 35 mg, which can be readily incorporated into the diet by consuming approximately one portion of grapes (78 g) or berries, such as strawberries (105 g), raspberries (90 g), blueberries (21 g), or blackberries (39 g).
Similarly, the difference in flavones between the top and bottom quintiles was 3.6 mg, equivalent to that found in approximately 2.5 oranges.
These results "are of public-health importance because the intakes associated with these findings are easily achievable through the habitual diet" and make a significant contribution to the knowledge base needed to refine the current fruit and vegetable dietary recommendations, the authors conclude.
The authors have reported no relevant financial relationships.
J Nutr. 2014;144. Abstract