Herb works like modern-day prescription drugs used to treat diabetes, study suggest

An herb used in traditional Indian medicine to treat diabetes seems to lower blood sugar and insulin levels in a manner similar to prescription drugs, a new study reports.Researchers gave extracts of the herb Salacia oblonga to 39 healthy adults, and the results were promising. The largest dose of the herb extract – 1,000 milligrams – decreased insulin and blood glucose levels by 29 and 23 percent, respectively.

“These kinds of reductions are similar to what we might see with prescription oral medications for people with diabetes,” said Steve Hertzler, a study co-author and an assistant professor of nutrition at Ohio State University.

Salacia oblonga, which is native to regions of India and Sri Lanka, binds to intestinal enzymes that break down carbohydrates in the body. These enzymes, called alpha-glucosidases, turn carbohydrates into glucose, the sugar that circulates throughout the body. If the enzyme binds to the herbal extract rather than to a carbohydrate, then less glucose gets into the blood stream, resulting in lowered blood glucose and insulin levels.

“Lowering blood glucose levels lowers the risk of disease-related complications in people with diabetes,” Hertzler said. “Also, poor compliance with diabetes medications often hinders the effectiveness of these drugs. It may be easier to get someone to take an herb with food or in a beverage, as opposed to a pill.”

The study appears in a recent issue of the Journal of the American Dietetic Association.

Thirty-nine healthy adults participated in four separate meal tolerance tests. These meals, which were given in beverage form, were spaced three to 14 days apart. Each participant fasted for at least 10 hours before consuming the test beverage.

Participants were asked to drink about two cups’ worth of the chilled beverage, which contained zero, 500, 700 or 1,000 milligrams of Salacia oblonga extract. Afterward, the researchers used the finger-prick method to draw blood samples from each person every 15 to 30 minutes for three hours. These blood samples were used to determine insulin and blood glucose concentrations. The biggest changes in blood glucose and insulin levels usually happen within the first two hours after eating.

The beverage that contained the highest concentration of the herbal extract – 1,000 milligrams – provided the most dramatic reduction in insulin and blood glucose levels. Insulin levels were 29 percent lower, while blood glucose levels were 23 percent lower as compared to the control drink, which contained no herbal extract.

As Salacia oblonga can cause intestinal gas, the researchers had the study participants collect breath hydrogen samples hourly for eight hours after drinking the test beverage. The participants collected their breath in small plastic tubes. The researchers then analyzed these breath samples for hydrogen and methane content – the level of either substance in the breath corresponds to the level contained in the colon.

The subjects also rated the frequency and intensity of nausea, abdominal cramping and distention and gas for two days after consuming each test meal.

While the test beverages containing Salacia oblonga caused an increase in breath hydrogen excretion, reports of gastrointestinal discomfort were minimal, Hertzler said.

Right now he and his colleagues are trying to figure out what dose of the herb is most effective, and when it should be taken relative to a meal.

“We want to know how long it takes for the herb to bind to the enzymes that break down carbohydrates,” Hertzler said. “The participants in this study took the herb with their meal, but maybe taking it before eating would be even more effective.”

The researchers also want to study the effects of Salacia oblonga in people with diabetes.

“A lot of studies show that lowering blood sugar levels reduces the risk for all kinds of diabetes-related complications, such as kidney disease and nerve and eye damage,” Hertzler said. “We want to see if this herb has this kind of effect.”

Salacia oblonga is still relatively difficult to find in the United States, Hertzler said, although there are manufacturers that sell the herb through the Internet.

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Article adapted by MD Only Weblog from original press release.
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Contact: Steve Hertzler
Ohio State University

This study was supported by the Ross Products Division of Abbott Laboratories in Columbus.

Hertzler is continuing to conduct Salacia oblonga studies with the Ross Products Division of Abbott Laboratories. He has no links to the company beyond this affiliation.

Hertzler conducted the work with former Ohio State colleague Patricia Heacock, who is now at Rutgers, the State University of New Jersey; Jennifer Williams, a clinical scientist with Ross Products Division, Abbott Laboratories; and Bryan Wolf, a former research scientists with Ross Products Division.

Early diet modification may prevent type 1 diabetes in children

Within the next 10 years the EU-funded Diabetes Prevention study, part of an international study called TRIGR (Trial to Reduce IDDM in the Genetically at Risk), coordinated at the University of Helsinki, Finland, will generate a definite answer to the question whether early nutritional modification may prevent type 1 diabetes later in childhood.

Type 1 diabetes is a growing health problem among European children. European data indicate that the disease incidence has increased five-six-fold among children under the age of 15 years after World War II, and there are no signs that the increase in incidence is levelling off. The most conspicuous increase has been seen among children under the age of 5 years.

The TRIGR study is the first study ever aimed at primary prevention of type 1 diabetes. The study is designed to answer to the question whether excluding cow’s milk protein from the infant’s diet decreases the risk of future diabetes. All subjects are followed for 10 years to get information on whether the dietary recommendations for infants at increased genetic risk of type 1 diabetes should be revised.

Starting in May 2002, 76 study centres from 15 countries (Australia, Canada, the Czech Republic, Estonia, Finland, Germany, Hungary, Italy, Luxembourg, the Netherlands, Poland, Spain, Sweden, Switzerland and USA) have been recruiting families for the study. To be eligible the newborn infant has to have at least one family member (mother, father and/or sib) affected by type 1 diabetes and carry a HLA genotype conferring increased risk for type 1 diabetes. The initial recruitment target of 2032 eligible infants was reached at the be-ginning of September 2006, but the Study Group has decided to continue recruitment till the end of December 2006 (when the EU contribution will finish) to make the study even more powerful statistically.

A majority of the study participants (52%) have been recruited in Europe. The International Coordinating Cen-tre (ICC) is located at the University of Helsinki, Helsinki, Finland and the Data Management Unit (DMU) at the University of South Florida, Tampa, Florida, USA. The trial has logistically been a true challenge for both the ICC and DMU. DMU has been successful in establishing a secure, real-time, web-based, interactive data management system that works extremely well. This system can be directly applied to future international mul-ticentre studies.

The TRIGR study is generating a wealth of information on breast-feeding practices, infant nutrition and growth in young children in various countries. At 2 weeks of age almost all the participating infants were breast-fed. Exclusive breast-feeding continued longer in Europe than in North America. More than one third of the infants (35 %) received other foods in addition to breast milk and/or infant formulas at the age of 4 months, while WHO recommends that supplementary food should be introduced at the earliest by the age of 6 months. In Europe the first foods to be introduced are typically vegetables and fruits, whereas gluten-free cereals are most commonly introduced in North America.

Newborn infants in Northern Europe (NE) had a higher birth weight but a shorter birth length than infants in Central and Southern Europe (CSE). The NE children remained heavier than those from CSE at least up to the age of 18 months. The NE children were also taller than the CSE children starting already from the age of 3 months up to the age of 18 months. Accelerated growth in infancy has been identified as a risk factor for type 1 diabetes later in childhood. Accordingly the observed growth pattern may contribute to the higher incidence of type 1 diabetes in NE compared to CSE.

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Article adapted by MD Only Weblog from original press release.
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Contact: Hans K. Åkerblom
University of Helsinki

More information:
Study websites: http://www.trigr.org

Soft drinks linked to development of diabetes in children

Researchers have found new evidence that soft drinks sweetened with high-fructose corn syrup (HFCS) may contribute to the development of diabetes, particularly in children. In a laboratory study of commonly consumed carbonated beverages, the scientists found that drinks containing the syrup had high levels of reactive compounds that have been shown by others to have the potential to trigger cell and tissue damage that could cause the disease, which is at epidemic levels. HFCS is a sweetener found in many foods and beverages, including non-diet soda pop, baked goods, and condiments. It is has become the sweetener of choice for many food manufacturers because it is considered more economical, sweeter and more easy to blend into beverages than table sugar. Some researchers have suggested that high-fructose corn syrup may contribute to an increased risk of diabetes as well as obesity, a claim which the food industry disputes. Until now, little laboratory evidence has been available on the topic.

In the current study, Chi-Tang Ho, Ph.D., conducted chemical tests among 11 different carbonated soft drinks containing HFCS. He found ‘astonishingly high’ levels of reactive carbonyls in those beverages. These undesirable and highly-reactive compounds associated with “unbound” fructose and glucose molecules are believed to cause tissue damage, says Ho, a professor of food science at Rutgers University in New Brunswick, N.J. By contrast, reactive carbonyls are not present in table sugar, whose fructose and glucose components are “bound” and chemically stable, the researcher notes.

Reactive carbonyls also are elevated in the blood of individuals with diabetes and linked to the complications of that disease. Based on the study data, Ho estimates that a single can of soda contains about five times the concentration of reactive carbonyls than the concentration found in the blood of an adult person with diabetes.

Ho and his associates also found that adding tea components to drinks containing HFCS may help lower the levels of reactive carbonyls. The scientists found that adding epigallocatechin gallate (EGCG), a compound in tea, significantly reduced the levels of reactive carbonyl species in a dose-dependent manner when added to the carbonated soft drinks studied. In some cases, the levels of reactive carbonyls were reduced by half, the researchers say.

“People consume too much high-fructose corn syrup in this country,” says Ho. “It’s in way too many food and drink products and there’s growing evidence that it’s bad for you.” The tea-derived supplement provides a promising way to counter its potentially toxic effects, especially in children who consume a lot of carbonated beverages, he says.

But eliminating or reducing consumption of HFCS is preferable, the researchers note. They are currently exploring the chemical mechanisms by which tea appears to neutralize the reactivity of the syrup.

Ho’s group is also probing the mechanisms by which carbonation increases the amount of reactive carbonyls formed in sodas containing HFCS. They note that non-carbonated fruit juices containing HFCS have one-third the amount of reactive carbonyl species found in carbonated sodas with HFCS, while non-carbonated tea beverages containing high-fructose corn syrup, which already contain EGCG, have only about one-sixth the levels of carbonyls found in regular soda.

In the future, food and drink manufacturers could reduce concerns about HFCS by adding more EGCG, using less HFCS, or replacing the syrup with alternatives such as regular table sugar, Ho and his associates say. Funding for this study was provided by the Center for Advanced Food Technology of Rutgers University. Other researchers involved in the study include Chih-Yu Lo, Ph.D.; Shiming Li, Ph.D.; Di Tan, Ph.D.; and Yu Wang, a doctoral student.

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Article adapted by MD Only Weblog from original press release.
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Contact: Charmayne Marsh
American Chemical Society

The American Chemical Society — the world’s largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

 

The Role of Sleep Deprivation on Academic Performance in Teens

A survey of sleep-deprived teens finds they think that a later start time for school and tests given later in the school day would result in better grades. The survey was presented at the American Thoracic Society 2007 International Conference, on Sunday, May 20.The survey of 280 high school students confirmed what most parents with a teenager know: they are not getting enough sleep. More sleep would translate into improved academic performance, according to the teens questioned. They all attended Harriton High School in suburban Philadelphia, where the school day begins at 7:30 a.m. and ends at 2:25 p.m.

The survey found that:

• 78% of students said it was difficult to get up in the morning
• Only 16% said they regularly had enough sleep
• 70% thought their grades would improve if they had more sleep
• 90% thought their academic performance would improve if school were to start later

The surveyed teens said they do not feel alert while taking tests during early morning periods, and they do not think they can perform at the pinnacle of their ability during the early morning hours. Most students said they thought the best time to take a test would be from 11 a.m. to 1 p.m. They thought they would perform better academically and that their grades would improve if they could sleep longer.

Richard Schwab, M.D., of the University of Pennsylvania, conducted the study with his daughter Amanda, one of the sleep-deprived teens who attended Harriton High School. “I watched her get up early for four years, and saw how difficult it was,” Dr. Schwab says. “Teenagers need more sleep than adults and their circadian rhythms are phase shifted so that their ideal bedtime is midnight to 1:00 a.m.; yet they have to get up at 6:30 or earlier for high school.

While adults usually need 7 to 8 hours of sleep, teens need 8 to 9 hours, he says. In addition, teens go to bed much later – their biological clock often keeps them up until 1 a.m. to 2 a.m. Because they have to get up so early for school, many teens achieve only 6 ½ to 7 hours of sleep or, in some cases, much less. That means they tend to sleep in on the weekends, often until 11 am or later, to try to make up for their sleep deficit.

“Right now, high schools usually start earlier in the morning than elementary schools. But if school start times were based on sleep cycles, elementary schools should start at 7:30 and high schools at 8:30 or 8:45 – right now it’s the reverse. School systems should be thinking about changing their start times. It would not be easy—they would have to change the busing system—but it would increase their student’s sleep time and likely improve their school performance.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Suzy Martin
American Thoracic Society

Reduce the risk of hypertension by 50 percent drinking skim milk

The American Journal of Clinical Nutrition is the peer-reviewed journal of international reference in the field of nutrition. In its latest issue, of November, it published an article which demonstrated that non-fat milk products can reduce the risk of hypertension by 50%, while nevertheless there is no appreciable connection between that disease and the consumption of whole milk.

The research was carried out by a team of researchers from the University of Navarra and Álvaro Alonso, currently a researcher in the School of Public Health at Harvard University who is the lead author of the article.

Research population of 6,000 persons.

This was a study which evaluated the relationship between the consumption of milk products and the risk of developing arterial hypertension.

They performed a research project that followed 6,000 people over the course of two years.

Those persons with an elevated consumption of skimmed milk and milk products showed a reduction of 50% in their risk of developing hypertension, compared with those with a low consumption or who did not consume these products. Nevertheless, no relationship was encountered between the consumption of whole milk products and the risk of hypertension.

These results can contribute to a clearer definition of dietary guidelines for the prevention of arterial hypertension. In particular, although data from prior studies indicated a possible preventative role of lactose products in the development of arterial hypertension, these results have been the first to demonstrate that this association exists in adults.

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Article adapted by MD Only Weblog from original press release.
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Contact: Garazi Andonegi
Elhuyar Fundazioa

Lack of sleep doubles children and adults risk of obesity

Research by Warwick Medical School at the University of Warwick has found that sleep deprivation is associated with an almost a two-fold increased risk of being obese for both children and adults.

Early results of a study by Professor Francesco Cappuccio of the University of Warwick’s Warwick Medical School were presented to the International AC21 Research Festival hosted this month by the University of Warwick.

The research reviewed current evidence in over 28,000 children and 15,000 adults. For both groups Professor Cappuccio found that shorter sleep duration is associated with almost a two-fold increased risk of being obese.

The research also suggests that those who sleep less have a greater increase in body mass index and waist circumference over time and a greater chance of becoming obese over time.

Professor Cappuccio says:

“The ‘epidemic’ of obesity is paralleled by a ‘silent epidemic’ of reduced sleep duration with short sleep duration linked to increased risk of obesity both in adults and in children.These trends are detectable in adults as well as in children as young as 5 years.”

Professor Cappuccio points out that short sleep duration may lead to obesity through an increase of appetite via hormonal changes caused by the sleep deprivation. Lack of sleep produces Ghrelin which, among other effects, stimulates appetite and creates less leptin which, among other effects, suppresses appetite. However he says more research is needed to understand the mechanisms by which short sleep is linked to chronic conditions of affluent societies, such as obesity, diabetes and hypertension.

Francesco Branca, the Regional Adviser for nutrition and food security in the World Health organisation (WHO) Regional Office for Europe said:

“This is an interesting piece of research putting together different lifestyle aspects with food choices. We need more research on the obese environment – the integration between medical research and socio-political research is something we should be exploring more.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Peter Dunn
University of Warwick

Lack of sleep linked to children behavioral, learning problems

The first investigation of developmental sleep duration patterns throughout childhood shows that children just beginning school and who get little sleep are more likely to have behavioral and cognitive problems in the classroom, according to a study published in the September 1 issue of the journal SLEEP.

The study, authored by Jacques Montplaisir, MD, of the Sleep Disorders Center at Sacre-Coeur Hospital in Montreal, Quebec, Canada, focused on 1,492 children, who were studied annually from five months of age to six years. A questionnaire, filled out by the children’s mothers, measured each child’s hyperactivity-impulsivity (HI), inattention and daytime sleepiness scores for each of those years.

Four developmental sleep duration patterns were identified in the study: short persistent (six percent), composed of children sleeping less than 10 hours per night until the age of 6 years; short increasing (4.8 percent), composed of children who slept fewer hours in early childhood but whose sleep duration increased around 41 months of age; 10-hour persistent (50.3 percent), composed of children who slept persistently approximately 10 hours per night; and 11-hour persistent (38.9 percent), composed of children who slept persistently around 11 hours each night.

According to Dr. Montplaisir, the study found no difference in sleep duration between weekdays and weekends, indicating that children were not compensating on the weekend for sleep loss occurring during the week, even in the group of short persistent sleepers. Short increasing sleepers, who had evidence of a nocturnal sleep consolidation problem before the age of 41 months, did not compensate their short nighttime sleep duration by more daytime sleep at 29 months, added Dr. Montplaisir.

The results indicate that a modest but chronic reduction of just one hour of sleep nightly in early childhood can affect the child’s cognitive performance at school entry. Short sleep duration multiplied by 3.1 the risk of low performance on the Peabody Picture Vocabulary Test–Revised. This suggests that language acquisition and the consolidation of new words into memory could be significantly impeded by chronically shortened sleep duration throughout childhood, said Dr. Montplaisir. Low performance on the Block Design subtest was also observed in the short increasing sleep group. This means that, although sleep duration improved at three years of age, the risk of scoring low on the Block Design subtest at six years of age remained more than 2.4 times higher. This finding points to an early critical period for cognitive development that may be jeopardized by short sleep duration, noted Dr. Montplaisir.

The results also demonstrate a significant relationship between high HI scores at six years of age and a short increasing sleep duration pattern. Although sleep duration improved at three years of age, the risk for high HI scores at six years of age remained 3.2 times higher. There is a critical period in early childhood where the lack of sleep is particularly detrimental on various aspects of development even if the sleep duration normalizes later on, warned Dr. Montplaisir.

“The results of this paper highlight the importance of giving a child the opportunity to sleep at least 10 hours a night throughout childhood, especially before the age of three-and-a-half years, to ensure optimal cognitive performance at school entry,” said Dr. Montplaisir.

It is recommended that children in pre-school sleep between 11-13 hours a night, and school-aged children between 10-11 hours of sleep a night.

The American Academy of Sleep Medicine (AASM) advises children to follow these steps to get a good night’s sleep:

• Follow a consistent bedtime routine.
• Establish a relaxing setting at bedtime.
• Get a full night’s sleep every night.
• Avoid foods or drinks that contain caffeine, as well as any medicine that has a stimulant, prior to bedtime.
• Do not go to bed hungry, but don’t eat a big meal before bedtime either.
• The bedroom should be quiet, dark and a little bit cool.
• Get up at the same time every morning.

Parents who suspect that their child might be suffering from a sleep disorder are encouraged to consult with their child’s pediatrician or a sleep specialist.

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Article adapted by MD Only Weblog from original press release.
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Contact: Jim Arcuri
American Academy of Sleep Medicine

SLEEP is the official journal of the Associated Professional Sleep Societies, LLC, a joint venture of the AASM and the Sleep Research Society.

SleepEducation.com, a Web site maintained by the AASM, provides information about various sleep disorders, the forms of treatment available, recent news on the topic of sleep, sleep studies that have been conducted and a listing of sleep facilities.

Caffeine Boosts Blood Pressure and Stress Hormones All Day

People who drink four or five cups of coffee throughout the morning have slightly elevated blood pressure and higher levels of stress hormones all day and into the evening, creating a scenario in which the body acts like it is continually under stress, according to a group of Duke University Medical Center scientists.In a study of 72 habitual coffee drinkers, the researchers found that subjects produced more adrenaline and noradrenalin and had higher blood pressure on days when they drank caffeine compared with days they abstained. The two stress hormones are vital to helping the body react quickly in times of danger or stress, but they can damage the heart over a lifetime of heightened production, said James Lane, associate research professor of psychiatry at Duke.

Lane prepared results of his study, funded by the National Heart, Lung and Blood Institute, for presentation Thursday to a meeting of the 1999 Society of Behavioral Medicine.

“Moderate caffeine consumption makes a person react like he or she is having a very stressful day,” Lane said in an interview before the meeting. “If you combine the effects of real stress with the artificial boost in stress hormones that comes from caffeine, then you have compounded the effects considerably.”

During the two-week study, the subjects experienced, on average, a 32 percent increase in adrenalin and a 14 percent increase in noradrenaline on days when they consumed caffeine. Their blood pressure rose an average of 3 points.

Lane’s study builds on smaller ones in which he found that caffeine boosted blood pressure, heart rate and stress hormones in subjects who drank 4 to 5 cups of caffeine per day. In the current study, Lane replicated those findings and added to them by showing that subjects’ blood pressures and stress hormone levels stayed elevated until bedtime, even though they last consumed caffeine between noon and 1 p.m.

Occasional surges of stress hormones temporarily raise heart rate, blood pressure and mental acuity — long enough to accomplish the task at hand. But an excess of stress hormones has been shown to compromise health in a variety of ways, from damaging blood vessels to weakening the immune system.

In addition, even the small boost in blood pressure seen in this study — an average of 3 points during the day and evening — can have clinical significance, Lane said. A review of nine major studies of blood pressure and heart-disease risk showed that a 5-point difference in diastolic blood-pressure — the lower number used to assess health risk — was associated with at least a 34 percent increase in stroke and a 21 percent increase in the incidence of coronary heart disease

While researchers have long known that caffeine can boost stress hormones and blood pressure, Lane said most studies have been conducted in a laboratory setting under tightly controlled circumstances where a single dose of caffeine is compared to none in a short time span. Lane said his body of research is unique because it measures blood pressure, heart rate and stress hormone levels at timed intervals during normal working conditions, while subjects are exposed to a range of moods and activities.

“You can measure how caffeine affects people in the laboratory, but that doesn’t tell you what effects the drug has in the real world when people are exposed to normal stressors and activities,” he said.

In the current study, Lane also studied the effects of caffeine on women taking oral contraceptives, since previous research suggested that this population might be more responsive to the negative effects of caffeine. But Lane found no such effect. In fact, women taking oral contraceptives showed slightly less of a stress response to caffeine than a control group of women.

Lane’s next study will measure the effects of eliminating caffeine from the diets of people with high blood pressure. The goal is to see if stopping caffeine use can be a useful therapy in reducing hypertension, along with diet, exercise and salt reduction.

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Article adapted by MD Only Weblog from original press release.
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Contact: Rebecca A. Levine
Duke University Medical Center

Drinking coffee elevates plasma homocysteine raising risk of coronary heart disease

High plasma homocysteine concentration is associated with an increased risk of cardiovascular disease, and consumption of unfiltered and filtered coffee raises homocysteine levels. As yet, it is unclear which substances in brewed coffee are responsible for its homocysteine-raising properties. In an article published in this month’s American Journal of Clinical Nutrition, Verhoef et al. investigated the effects of caffeine alone and in brewed coffee on homocysteine concentrations in a group of healthy volunteers. Brewed coffee increased homocysteine levels within hours of consumption and seemed to have a particularly strong effect when taken after meals.

The 21 male and 27 female participants in the study, aged 19 to 65 years old, were all heavy coffee drinkers who consumed 6 or more cups of filtered or instant coffee daily. Thirty-one percent of the subjects were smokers, who are known to metabolize caffeine more rapidly than non-smokers. Three treatments, administered in random order for a period of 2 weeks each, consisted of either capsules containing 870mg of caffeine daily; 4 cups of strong filtered coffee that contained 870 mg of caffeine; or placebo capsules. Despite the fact that both treatments had a similar amount of caffeine, the average fasting homocysteine concentration rose by 11% after the subjects drank brewed coffee for 2 weeks, compared to a 5% increase after caffeine alone. The paper filter in the brewed coffee retained trace amounts of several substances that were suspected to be responsible for the rise in homocysteine concentrations, including chlorogenic acid (a polyphenolic compound) that is not removed by filtering.

Epidemiologic associatations between coffee consumption and CVD are conflicting; therefore, public health implications of the homocysteine-raising effects of caffeine and coffee will remain unclear until a causal relation between high homocysteine concentrations and CVD is proven.

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Article adapted by MD Only Weblog from original press release.
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Contact: Elizabeth Horowitz
American Journal of Clinical Nutrition

Verhoef, Petra et al. Contribution of caffeine to the homocysteine-raising effect of coffee: a randomized controlled trial in humans. Am J Clin Nutr 2002;76:1244-8.

This information should not be construed as medical advice. If you have a medical concern, consult your doctor. To see the complete text of this article, please go to:

http://www.faseb.org/ajcn/Dec2002/13024.Verhoef.PDF

Just Moderate Caffeine Use Boosts Blood Pressure, Potential For Heart Disease

Drinking a few extra mugs of coffee each day can boost blood pressure, heart rate and stress levels enough to increase a person’s risk of developing heart disease over a lifetime of moderate caffeine consumption, according to a Duke University researcher.In a study of 19 habitual coffee drinkers who wore “ambulatory” blood-pressure monitors throughout their daily jobs, the researcher found that the equivalent of four to five cups raised blood pressure an average of five points, compared to days when they consumed only one cup. The effect occurred within an hour of consumption, and the subjects’ blood pressure remained elevated throughout the day, the study found.

The volunteers also reported higher levels of stress during the day when they received the higher, 500-milligram dose of caffeine, and they showed a corresponding increase in heart rate, said James Lane, associate research professor of psychiatry at Duke and lead author of the study. Results of the study, funded by the National Heart, Lung and Blood Institute, are published in the May issue of the journal Psychosomatic Medicine.

While a 5-point increase in blood pressure is not excessive, it can have significant clinical implications over time, Lane said. A review of nine major studies of blood-pressure and cardiovascular-disease risk showed that a 5-point difference in diastolic blood pressure — the lower number used to assess health risk — was associated with at least a 34 percent increase in the incidence of stroke and a 21 percent increase in the incidence of coronary heart disease.

In another unrelated study, called the Hypertension Detection and Follow-up Program, researchers reported that reducing blood pressure by five points through medication was associated with a 20 percent reduction in 5-year mortality, Lane said.

“The relevant message here is that the more caffeine you consume during the day in coffee, tea or soft drinks, the higher your blood pressure is likely to be,” Lane said. “Over many years, this increase in blood pressure may heighten your risk of suffering a heart attack or stroke, even if you don’t have high blood pressure now.”

While researchers have long known that caffeine boosts blood pressure, nearly all the studies have been conducted in a laboratory setting under tightly controlled circumstances where a single dose of caffeine is compared to none in a short time span. Lane said his study is among the first to analyze blood pressure levels at 15-minute intervals during normal working conditions, while subjects were exposed to a range of moods and activities, from sitting to standing to walking.

“You can measure how caffeine affects people in the laboratory, but that doesn’t tell you what effects the drug has in the real world when people are exposed to normal stressors and activities,” he said.

In previous studies conducted over the past 15 years, Lane has shown that caffeine raises levels of adrenalin, the body’s major stress chemical, during everyday work activities, indicating that caffeine made the day more stressful. The question he wanted to answer in the current study was whether or not caffeine acted directly on blood pressure, or whether it elevated blood pressure through its effect on stress and activity levels.

By correlating the blood pressure readings with the subjects’ self-reports of their activities and moods throughout the day, the Duke researchers were able to rule out the possibility that caffeine was simply acting through a stress response or burst of physical activity.

“Essentially, we have demonstrated that the effects of caffeine on ambulatory blood pressure cannot be accounted for by changes in activity, posture (sitting, standing or walking) or perceived stress,” Lane said. “This strengthens the evidence that caffeine is working directly on blood pressure rather than through other mediating factors.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Rebecca A. Levine
Duke University Medical Center