Active Ingredient in Chinese Herb Used to Reduce High Blood Pressure

Some 50 million Americans have hypertension, that is, blood pressure measuring above the normal range (less than 120/80 mmHg). If untreated, it can lead to heart attacks, strokes, or kidney disease. Lifestyle changes are the first-stage treatment for the disease, but if they fail, medications are prescribed.

Many patients with high blood pressure have sought relief from complementary and alternative medicine (CAM). In so doing, many have consumed danshen, a Chinese herb used in Oriental medicine that promotes blood flow and treats cardiovascular disease.

Tanshinone IIA is an active ingredient of danshen. Since tanshinone IIA is widely available, a team of researchers has used it to investigate if this active ingredient can reduce blood pressure. In a soon-to-be-released study, using an animal model, the scientists have found that tanshinone IIA does reduce blood pressure.

Summary of Methodology

To assess the effect of tanshinone IIA, the protocol consisted of several parts. The researchers applied the 2-kidney-1-clip protocol to induce renal hypertension in male golden Syrian hamsters. The animals were anesthetized and a retroperitoneal approach was used to place a silver clip to constrict the right renal artery. Sham-operated hamsters and mice underwent the same procedure, except for the placement of a clip.

Both sets of hamsters received 50 ¦Ìg of tanshinone IIA/100g of body weight once a day for two weeks. After the two-week treatment period, mean arterial blood pressure was measured in the right carotid artery. To examine the microvascular actions of tanshinone IIA researchers applied it topically to the hamsters¡¯ cheek pouch or mice cremaster muscles to achieve the final concentration of one ¦Ìg/ml or five ¦Ìg/ml. After the application of tanshinone IIA, the experiment was continued for an additional 60-minute period in order to measure arteriolar diameter and peri-arteriolar nitric oxide concentration.

Results

Tanshinone IIA was found to have significantly reduced blood pressure in the hamsters. The experimental constriction of the renal artery increased mean arterial pressure to 161.2¡À6.9 mmHg relative to 114.3¡À9.2 mmHg in age-matched hamsters. Treatment with 50 ¦Ìg tanshinone IIA/100g body for two weeks reduced the mean arterial pressure from 161.2¡À6.9 to 130.0¡À7.8 mmHg.

The research team also discovered that tanshinone IIA caused widening of the arterioles in the hamster cheek pouch microcirculation via enhanced expression of endothelial nitric oxide synthase. The topical application of tanshinone IIA at one ¦Ìg/ml and five ¦Ìg/ml caused significant dose-related vasodilation, indicated by the increased agent/control ratio of arteriolar diameters from 1.0 to 1.25¡À0.08 and 1.57¡À0.11, respectively, in the hamster cheek pouch. The increase in arteriolar diameter ratio was significant relative to the vehicle for each concentration as well as for comparison between the two concentrations of tanshinone IIA.

Conclusions

As a result of the findings the researchers concluded that tanshinone IIA: (1) significantly reduced blood pressure in hamsters, (2) enhanced the expression of endothelial nitric oxide synthase, (3) increased the production of nitric oxide and (4) induced blood pressure changes through vasodilation in hamster blood microvessels. While the mechanisms of how tanshinone IIA or danshen work in hypertension are not yet fully understood, these results contribute to the effort to bring complementary and alternative medicine and allopathic care closer together in the treatment of hypertensive patients.

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Article adapted by MD Only from original press release.
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Contact: Donna Krupa
American Physiological Society

Their study will soon be published in the American Journal of Physiology ¨C Heart and Circulatory Physiology (December 15, 2006), doi:10.1152/ajpheart.01027.2006, and is entitled Endothelial Nitric Oxide Synthase is a Molecular Vascular Target for the Chinese Herb Danshen in Hypertension. It was conducted by the team of David D. Kim, PhD, OMD; Fabiola A. S¨¢nchez, PhD; Ricardo G. Dur¨¢n, BS; Takehito Kanetaka, MD; and Walter N. Dur¨¢n, PhD, all of the Program in Vascular Biology, Department of Pharmacology and Physiology and Department of Surgery, UMDNJ-New Jersey Medical School, Newark, NJ.

JOURNAL PUBLICATION INFORMATION: American Journal of Physiology ¨C Heart and Circulatory Physiology Articles in Press, doi: 10.1152/ajpheart.01027.2006.

Physiology is the study of how molecules, cells, tissues and organs function to create health or disease. The American Physiological Society (APS) has been an integral part of this scientific discovery process since it was established in 1887.

A brisk walk daily is the easiest way to trim waistline

Research from Duke University Medical Center shows that even a modest amount of brisk walking weekly is enough to trim waistlines and cut the risk of metabolic syndrome (MetS), an increasingly frequent condition linked to obesity and a sedentary lifestyle.

It’s estimated that about a quarter of all U.S. adults have MetS, a cluster of risk factors associated with greater likelihood of developing heart disease, diabetes and stroke: large waist circumference, high blood pressure, high levels of triglycerides, low amounts of HDL, or “good” cholesterol, and high blood sugar. To be diagnosed with MetS, patients must have at least three of these five risk factors, and according to many studies, a growing number of people do.

But Johanna Johnson, a clinical researcher at Duke Medical Center and the lead author of a new study examining the impact of exercise on MetS, said a person can lower risk of MetS by walking just 30 minutes a day, six days per week. “That’s about 11 miles per week. And our study shows that you’ll benefit even if you don’t make any dietary changes.”

“The results of our study underscore what we have known for a long time,” said Duke cardiologist William Kraus. “Some exercise is better than none; more exercise is generally better than less, and no exercise can be disastrous.”

The study appears in the December 15 issue of the American Journal of Cardiology.

The results come from a multi-year, federally funded study called STRRIDE (Studies of a Targeted Risk Reduction Intervention through Defined Exercise) that examined the effects of varying amounts and intensity of exercise on 171 middle-aged, overweight men and women.

Before exercising regularly, 41 percent of the participants met the criteria for MetS. At the end of the 8-month exercise program, only 27 percent did.

“That’s a significant decline in prevalence,” said Johnson. “It’s also encouraging news for sedentary, middle-aged adults who want to improve their health. It means they don’t have to go out running four or five days a week; they can get significant health benefits by simply walking around the neighborhood after dinner every night.”

Still, some exercise regimens were better than others. Those who exercised the least, walking about 11 miles per week, gained significant benefit, while those who exercised the most, jogging about 17 miles per week, gained slightly more benefit in terms of lowered MetS scores.

One group puzzled the researchers, however. Those who did a short period of very vigorous exercise didn’t improve their MetS scores as much as those who performed less intense exercise a longer period.

Kraus said there may be more value in doing moderate intensity exercise every day rather than more intense activity just a few days a week.

In all three of the study’s exercise groups, waistlines got smaller over the 8-month period. In general, men who exercised saw greater improvement in their MetS risk factors than women. But Johnson points out that at baseline, the men generally had worse scores than women, “so they had more room to improve,” she said.

Over the course of the STRRIDE study, the inactive control group – those who didn’t change their diet or activity level at all – gained an average of about one pound and a half-inch around the waist. “That may not sound like much, but that’s just six months,” Kraus said. “Over a decade, that’s an additional 20 pounds and 10 inches at the beltline.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Michelle Gailiun
Duke University Medical Center

The study was funded by the National Institutes of Health.

Colleagues at Duke who contributed to the study include Cris Slentz, Gregory Samsa, Lori Bateman and Brian Duscha. Collaborating authors from East Carolina University include Joseph Houmard, Jennifer McCartney and Charles Tanner.

Hope for Diabetics at risk of blindness

Brand new research launched at the British Pharmaceutical Conference in Manchester is bringing hope to hundreds of people with diabetes who lose their sight each year as a side-effect of the disease.

People with diabetes commonly experience blindness, or a reduction in sight, when a lack of oxygen at the back of the eye causes tiny blood vessels to overgrow into the vitreous humour, which is a jelly like substance. This jelly like substance is removed during surgery to treat this problem.

Pharmaceutical researchers at the University of East Anglia have revealed that they are developing an artificial form of this vitreous humour so that it can be replaced following surgery or if it has been damaged or degenerated for other reasons.

Biologist Janine Morris working with Pharmacist Susan Barker and Biologist Julie Sanderson at the School of Chemical Sciences and Pharmacy, University of East Anglia, is identifying the essential characteristics of the human and pig vitreous humour so that they can be mimicked artificially.

She says: “I am currently making a gel that imitates the vitreous humour and which is non-cytotoxic to the human eye. The substance will also include anti-angiogenic drugs to prevent the blood vessels re-growing and the original damage re-occurring.”

Placing this artificial jelly into the damaged eye should certainly improve and potentially restore lost sight. Janine Morris says that the research, which is in the preliminary stages, is good news for diabetes sufferers who will be protected against recurring damage. “The idea that we can potentially improve and maintain sight for diabetes sufferers by replacing the vitreous humour is amazing,” she says.

The vitreous humour is a clear gel-like substance that fills the space between the lens and the retina of the eye. It is 99% water but also contains collagen fibres, inorganic salts, acids and sugar.

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Article adapted by MD Only Weblog from original press release.
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For further information please visit:
The University of East Anglia

Diabetes is the leading cause of blindness among people aged 20-74 in Minnesota. Each year, according to the Minnesota Department of Health (MDH), between 400 and 700 Minnesotans go blind due to diabetes complications. Even when blood sugar is controlled, 60% of those having diabetes for more than 15 years will experience some form of diabetic eye disease in their lifetime.November is American Diabetes Month. This is a good time to schedule your annual dilated eye exam, urges the Minnesota Optometric Association (MOA), because type 2 diabetes can be caught early with this exam, and treated. MDH statistics show that of the 276,000 Minnesotans who have diabetes, 96,000 are unaware that they have it.

Currently, only eight in 10 Minnesotans with diabetes have a dilated eye exam every two years. “Most people do not realize that diabetics are twice as likely to suffer from cataracts, diabetic retinopathy and glaucoma. People may have these diseases before they are aware of it,” said Dr. Dirk Colby, president of the MOA and a doctor of optometry with West Metro Ophthalmology, Golden Valley and Plymouth, Minnesota. “It is critical for diabetic patients to come in every year,” said Dr. Colby. “Waiting two years or even worse, not coming in at all, can have a catastrophic effect.”

Diabetes is taking its toll on Americans and Minnesotans with eye diseases and type 2 diabetes is increasing rapidly due to the increase in obesity and decrease in exercise. These two risk factors are the leading causes of type 2 diabetes.

Diabetic retinopathy, the most common diabetic eye disease, is the leading cause of blindness in Minnesota, and overall in the United States. Diabetic retinopathy is caused by changes in the blood vessels of the retina. In some people with diabetic retinopathy, retinal blood vessels may swell and leak fluid; in others, abnormal new blood vessels grow on the surface of the retina. These changes may result in vision loss or blindness.

Cataracts occur when the normally clear lens in the eye becomes cloudy, impairing vision. Clouded vision may make it more difficult to read, drive, or see clearly. Glaucoma, an increase in fluid pressure inside the eye, leads to optic nerve damage and vision loss.

To help prevent diabetic eye diseases, the American Diabetes Association recommends people suffering from diabetes should:

• Keep your blood sugar under good control. People who keep their blood sugar levels closer to normal are less likely to have retinopathy.
• Bring high blood pressure down. High blood pressure can make eye problems worse.
• Get a dilated eye exam by a family eye doctor every year. Your optometrist will use drops to enlarge your pupils to look inside your eyes.

The Minnesota Optometric Association (MOA) recommends you see your family eye doctor right way if you have any of the following problems:

• Your vision is blurry.
• You see double, spots or floaters
• One or both eyes hurt
• You feel pressure in your eye
• You can’t see things at the periphery as well as before
• You have trouble reading

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Article adapted by MD Only Weblog from original press release.
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Contact:
Jim Meffort-Nelson
minnesota.aoa.org

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 high blood pressure

If you’re middle age and sleep five or less hours a night, you may be increasing your risk of developing high blood pressure, according to a study released by Columbia University’s Mailman School of Public Health and the College of Physicians and Surgeons, and reported in Hypertension: Journal of the American Heart Association.”Sleep allows the heart to slow down and blood pressure to drop for a significant part of the day,” said James E. Gangwisch, PhD, lead author of the study and post-doctoral fellow in the psychiatric epidemiology training (PET) program at the Mailman School. “However, people who sleep for only short durations raise their average 24-hour blood pressure and heart rate. This may set up the cardiovascular system to operate at an elevated pressure.”

Dr. Gangwisch said that 24 percent of people ages 32 to 59 who slept for five or fewer hours a night developed hypertension versus 12 percent of those who got seven or eight hours of sleep. Subjects who slept five or fewer hours per night continued to be significantly more likely to be diagnosed with hypertension after controlling for factors such as obesity, diabetes, physical activity, salt and alcohol consumption, smoking, depression, age, education, gender, and ethnicity.

The researchers conducted a longitudinal analysis of data from the Epidemiologic Follow-up Studies of the first National Health and Nutrition Examination Study (NHANES I). The analysis is based on NHANES I data from 4,810 people ages 32 to 86 who did not have high blood pressure at baseline. The 1982-84 follow-up survey asked participants how many hours they slept at night. During eight to 10 years of follow-up, 647 of the 4,810 participants were diagnosed with hypertension. Compared to people who slept seven or eight hours a night, people who slept five or fewer hours a night also exercised less and were more likely to have a higher body mass index. (BMI is a measurement used to assess body fatness). They were also more likely to have diabetes and depression, and to report daytime sleepiness.

“We had hypothesized that both BMI and a history of diabetes would mediate the relationship between sleep and blood pressure, and the results were consistent with this,” Dr. Gangwisch said.

Sleep deprivation has been shown previously to increase appetite and compromise insulin sensitivity.

Short sleep duration was linked to a new diagnosis of high blood pressure among middle-aged participants, but the association was not observed among people age 60 or older, he said. Dr. Gangwisch said the differences between the younger and older subjects might be explained by the fact that advanced age is associated with difficulties falling and staying asleep. Another factor could be that subjects suffering from hypertension, diabetes, and obesity would be less likely to survive into their later years.

Among study limitations, researchers found that high blood pressure often goes undetected. An analysis of NHANES III data showed that over 30 percent of people who had high blood pressure didn’t know they had it.

Since the study is based on observational data, Dr. Gangwisch said more research is needed to confirm the association between short sleep duration and high blood pressure. “We need to investigate the biological mechanisms and, if confirmed, design interventions that will help people modify sleep behavior,” he said.

Dr. Gangwisch said the study’s main message is clear: “A good night’s sleep is very important for good health.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Stephanie Berger
Columbia University’s Mailman School of Public Health

Are You Fueling Your Heart For Life or Death?

An age-related decline in heart function is a risk factor for heart disease in the elderly. While many factors contribute to a progressive age-related decline in heart function, alterations in the types of fuels the heart uses to produce energy also play important roles. Jason Dyck and his research team at the University of Alberta have been studying the types of fuels used by the heart in young and aged mice. The young healthy heart normally used a balance of fat and sugar to generate energy to allow the heart to beat and pump blood efficiently. However, as the heart ages the ability to use fat as an energy source deteriorates. This compromises heart function in the elderly. Interestingly, at a time when the heart is using less fat for energy, Dyck has shown that a protein that is responsible for transporting fat into the contractile cells of the heart actually increases. Based on this finding, Dyck proposed that the mismatch between fat uptake and fat use in the heart could lead to an accumulation of fat in the heart resulting in an age-related decrease in heart function.

Using a genetically engineered mouse that is deficient in a protein that is responsible for transporting fat into the cells of the heart, Dyck studied these mice as they aged. These genetically altered mice have no choice but to mainly use sugar as a fuel source because they lack the protein that allows them to use fat as a primary fuel source. In an exciting new finding, Dyck showed that old genetically modified mice did not accumulate fat in their hearts, as did ordinary mice. In addition, Dyck and his team showed that these old genetically altered mice out-performed ordinary old mice on a treadmill test, were completely protected from age-related decline in heart function, and in many ways their hearts looked and performed like hearts from a young mouse. His findings suggest that the protein responsible for transporting fat into the contractile cells of the heart may be a candidate for drug inhibition and that this drug could protect the heart from aging.

This research holds great promise for human beings. Dyck hopes it will lead to the development of medications that inhibit the uptake of fatty acids into the heart and prevent and/or reverse the effects of aging on the heart muscle.

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Article adapted by MD Only Weblog from original press release.
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Contact: Kris Connor
University of Alberta

This study appears in the October 22 edition of Circulation.

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

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