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7 August 2009
Increased intakes of antioxidant anthocyanins may improve levels of HDL and LDL cholesterol, according to results of a new human study with 120 people.
Consumption of berry-derived anthocyanin supplements resulted in a 13.7 per cent increase in levels of HDL cholesterol, and a 13.6 per cent reduction in levels LDL cholesterol, according to findings published online ahead of print in the American Journal of Clinical Nutrition.
Chinese scientists from Sun Yat-Sen University randomly assigned 120 people aged between 40 and 65 with abnormal blood lipid levels (dyslipidemia) to receive either a daily dose of 320 mg of anthocyanins or placebo for 12 weeks.
The study builds on earlier results form animal studies, which showed beneficial effects of the antioxidant compounds on lipid levels.
High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year.
Using a double-blind, randomised, placebo-controlled trial design, the Chinese researchers studied the effects of a twice daily dose of 160 mg anthocyanins on the lipid levels of the participants.
After 12 weeks of supplementation, HDL cholesterol levels increased by almost 14 per cent in the anthocyanin group, compared to a rise of only 2.8 per cent in the placebo group. Furthermore, LDL cholesterol levels decreased by 13.6 per cent in the anthocyanin group, compared to an increase of 0.6 per cent in the placebo group.
The removal of cholesterol from cells, the so-called cellular cholesterol efflux, was found to increase by 20 per cent in the anthocyanin group, compared to a 0.2 per cent in the placebo group.
In terms of the potential mechanism, the activity of a protein called plasma cholesteryl ester transfer protein (CETP) was studied. CETP works by collecting triglycerides from LDL and exchanging them for cholesteryl esters from HDL, and also the reverse.
Supplements of the anthocyanins was found to reduce the activity of CETP by 6.3 per cent, while CETP activity fell by only 1.1 per cent in the placebo group, said the researchers.
“The change in HDL cholesterol was negatively correlated with the change in CETP activity,” they wrote. “The change in LDL cholesterol was positively correlated with the change in CETP mass,” they added.
“Anthocyanin supplementation in humans improves LDL- and HDL-cholesterol concentrations and enhances the cellular cholesterol efflux to serum,” wrote the researchers. “These benefits may be due to the inhibition of CETP,” they concluded.
6 August 2009
Avoiding caffeine, sticking to a schedule and drinking a glass of warm milk are the usual tips for a good night’s rest. But the right room temperature can also play a crucial role.
Studies have found that in general, the optimal temperature for sleep is quite cool, around 60 to 68 degrees Fahrenheit. For some, temperatures that fall too far below or above this range can lead to restlessness.
Temperatures in this range, it seems, help facilitate the decrease in core body temperature that in turn initiates sleepiness. A growing number of studies are finding that temperature regulation plays a role in many cases of chronic insomnia. Researchers have shown, for example, that insomniacs tend to have a warmer core body temperature than normal sleepers just before bed, which leads to heightened arousal and a struggle to fall asleep as the body tries to reset its internal thermostat.
For normal sleepers, the drop in core temperature is marked by an increase in temperature in the hands and feet, as the blood vessels dilate and the body radiates heat. Studies show that for troubled sleepers, a cool room and a hot-water bottle placed at the feet, which rapidly dilates blood vessels, can push the internal thermostat to a better setting.
THE BOTTOM LINE
A slightly cool room and a lower core temperature are optimal for sleep.
Drinking five or more cups of green tea per day may reduce the risk of blood- and lymph-based cancers by about 50 per cent, says a new study from Japan.
Compared to people who drank only one cup per day, five cups of green tea a day were associated with a 42 per cent reduction in hematologic malignancies, and a 48 per cent risk reduction in lymphoid neoplasms, according to findings published in the American Journal of Epidemiology.
The study, led by Toru Naganuma from Tohoku University School of Medicine in Japan, adds to the ever-growing body of science supporting the anti-cancer benefits of green tea and its polyphenols.
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
Naganuma and his co-workers followed 41,761 adults participating in the Ohsaki National Health Insurance Cohort Study. A questionnaire completed at the start of the study allowed the researchers to quantify green tea consumption.
During nine years of follow-up, the researchers documented 157 hematologic malignancies, including 119 cases of lymphoid neoplasms and 36 cases of myeloid neoplasms.
The risk reductions observed for people who drank five or more cups a day, compared to those who drank only cup, was not affected by the gender of the participants, or their body mass index.
While the result does not prove causality, it does support other studies which reported a protective effect of green tea and its constituents.
Being an epidemiological study, no measures were made of the polyphenol content of the tea consumed, and no mechanistic study was performed to identify the active component or components of the beverages.
Global tea market
The global tea market is worth about €790 (£540, $941) million, with green tea accounting for about 20 per cent of total global production, while black tea accounts for about 78 per cent.
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.
This has seen European demand surge, having reached 500 metric tonnes in 2003. Companies such as DSM, with its Teavigo boasting 95 per cent purity of epigallocatechin gallate (EGCG), and Taiyo International, with its Sunphenon claiming more than 90 per cent purity, position themselves firmly in specific catechin markets.
Vitamin D is known as the sunshine vitamin, and it has a lot of sunny benefits, but most Americans aren't getting them because they aren't getting enough of it.
Between 50 percent and 75 percent of Americans get suboptimal levels of vitamin D, according to a study published in the Archives of Internal Medicine.
Now a committee at the Institute of Medicine is meeting to determine whether the recommended daily intake of vitamin D should be increased. ABC medical contributor Dr. Marie Savard came on "Good Morning America" today to offer five ways vitamin D can aid your health and tell you how to get more of it.
Why People Are Vitamin D Deficient
Nature gave us only one good source of vitamin D, and that is the sun. We are meant to absorb vitamin D from the sun through our skin.
3 August 2009
Tomatoes are certainly nutritious — a good source of the antioxidants lycopene and beta-carotene. But consider this: if you eat a tomato without adding a little fat — say a drizzle of olive oil — your body is unlikely to absorb all these nutrients.
Scientists at Iowa State University figured this out a while ago. They recruited graduate students to eat bowls of salad greens with tomatoes and various types of salad dressings — from fat-free to regular Italian. "Basically once a month for several months we'd show up first thing in the morning," recalls participant Gregory Brown, now a professor of exercise science at the University of Nebraska. Researchers put IV lines into the participants' veins and drew blood samples before and after they'd eaten the salads in order to get precise measurements of the absorption of nutrients.
"The salads all tasted the same to me," says Brown. But when researchers went back and analyzed the blood samples they realized that people who had eaten fat-free or low-fat dressings didn't absorb the beneficial carotenoids from the salad. Only when they had eaten the oil-based dressing did they get the nutrients.
Carotenoids are the pigments responsible for red-, yellow- and orange-colored fruits and vegetables. And carotenoids are also found in dark green vegetables such as spinach. The compounds convert to Vitamin A in the body, and studies have found that carotenoids have anti-oxidant activity which may help protect cells from damage caused by free radicals. Human studies have linked high consumption of fruits and vegetables to reduced risk of cancer.
Beta-carotene researchers were not particularly surprised by the findings of the fat-free vs. regular Italian salad dressing study. "We already knew that carotenoids were fat soluble," explains Wendy White, a professor of Human Nutrition at Iowa State University. The results helped reinforce the idea that a little fat is healthy.
Chop And Chew
There are other ways to help maximize the absorption of carotenoid nutrients. Chopping or grating breaks down the plant material. "The finer the particle size ... the better the absorption of beta-carotene," explains White.
The findings of nutrition research often go against the grain of trendy food ideas. For instance, many people have heard that raw vegetables are best. But if you're eating carrots, it may be helpful to cook them gently. The heat can soften the food allowing more nutrients to be released.
A recent study in the Journal of Food Science suggests that some cooking methods may be better than others. Researchers at the University of Murcia in Spain cooked 20 different kinds of vegetables six different ways. Then they analyzed how well the foods retained antioxidants. They found that microwaving helped maintain the antioxidants, whereas boiling and pressure cooking led to the greatest losses.
Green beans, beets and garlic all did well with heat — maintaining beneficial phytonutrients after most kinds of cooking. The antioxidant value in carrots actually increased after cooking.
Experts explain that boiling may allow nutrients to leach into the pan water that people end up tossing out, especially with water-soluble nutrients such as Vitamin C and the B Vitamins.
Eat Plenty Of Colors
As testing methods have become more sensitive, scientists have the ability to peer into our foods and tally up all the phytonutrients that may be beneficial. But experts say the ways in which our bodies may use and absorb these compounds are complicated. Therefore, many experts say it's best not to fixate too much on how food is prepared. Instead, focus on eating more plant foods — of all colors.
Jeffrey Blumberg, an antioxidant expert at Tufts University, says "What's important is that you find a way to cook that's palatable to you so you're getting lots of plant foods."
Long known for its antioxidants, immune boosting and, most recently, antihypertensive properties, black tea could have another health benefit. Black tea may be used to control diabetes, according to a study in the Journal of Food Science, published by the Institute of Food Technologists.
Next to water, tea is the second most consumed beverage in the world. Researchers from the Tianjin Key Laboratory in China studied the polysaccharide levels of green, oolong and black teas and whether they could be used to treat diabetes. Polysaccharides, a type of carbohydrate that includes starch and cellulose, may benefit people with diabetes because they help retard absorption of glucose.
The researchers found that of the three teas, the polysaccharides in black tea had the most glucose-inhibiting properties. The black tea polysaccharides also showed the highest scavenging effect on free radicals, which are involved in the onset of diseases such as cancer and rheumatoid arthritis.
“Many efforts have been made to search for effective glucose inhibitors from natural materials,” says lead researcher Haixia Chen. “There is a potential for exploitation of black tea polysaccharide in managing diabetes.”