Blood pressure: 100 million Americans may be unnecessarily labeled abnormal

ScienceDaily (Mar. 9, 2011) — As many as 100 million Americans may currently be misclassified as having abnormal blood pressure, according to Dr. Brent Taylor from the Veterans Affairs Health Care System in Minneapolis and the University of Minnesota and his colleagues. Their findings show that these people are not actually more likely to die prematurely than those with 'normal' blood pressure, i.e. below 120/80. Taylor and colleagues' article in the Journal of General Internal Medicine, published by Springer, also shows that in those under 50, diastolic blood pressure* is the more important predictor of mortality, whereas in those over 50, systolic blood pressure* is the stronger predictor. The authors argue it is time to consider a new definition of 'normal' blood pressure.

Taylor and colleagues examined the independent contribution of diastolic blood pressure (DBP) and systolic blood pressure (SBP) on mortality, as well as how these relationships might affect the number of Americans currently labeled as having abnormal blood pressure.

The authors looked at data for 13,792 people from the National Health and Nutrition Examination Survey, which enrolled participants in 1971-76 and followed them up for two decades -- they studied DBP, SBP and long-term survival data specifically. In order to assess the underlying distribution of untreated blood pressure in American adults by age, Taylor and team also looked at data for 6,672 adults from the first National Health Examination Survey carried out between 1959 and 1962.

They found that in people aged over 50, those with SBPs above 140, independent of DBP, were significantly more likely to die prematurely. In those aged 50 or less, DBPs above 100 were linked to significant increases in premature death. The authors' analysis offers alternative cut-off points for the definition of 'normal'.

Dr. Taylor concludes: "Our findings highlight that the choice of approach used to define normal blood pressure will impact literally millions of Americans. If we cannot reliably see an effect on mortality in a large group of individuals followed for nearly 20 years, should we define the condition as abnormal? We believe considering this kind of approach represents a critical step in ensuring that diagnoses are given only to those with a meaningful elevation in risk, and targeted towards individuals most likely to benefit."

* Diastolic blood pressure is the lowest pressure within the bloodstream, occurring between heart beats i.e. when the heart relaxes. Systolic blood pressure is the highest pressure within the bloodstream, occurring during each heart beat i.e. when the heart contracts.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Springer Science+Business Media, via AlphaGalileo.

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Sugar-sweetened drinks associated with higher blood pressure

ScienceDaily (Mar. 1, 2011) — Soda and other sugar-sweetened beverages such as fruit drinks are associated with higher blood pressure levels in adults, researchers report in Hypertension: Journal of the American Heart Association.

In the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP), for every extra sugar-sweetened beverage drunk per day participants on average had significantly higher systolic blood pressure by 1.6 millimeters of mercury (mm Hg) and diastolic blood pressure higher by 0.8 mm Hg. This remained statistically significant even after adjusting for differences in body mass, researchers said.

Researchers found higher blood pressure levels in individuals who consumed more glucose and fructose, both sweeteners that are found in high-fructose corn syrup, the most common sugar sweetener used by the beverage industry.

Higher blood pressure was more pronounced in people who consumed high levels of both sugar and sodium. They found no consistent association between diet soda intake and blood pressure levels. Those who drank diet soda had higher mean BMI than those who did not and lower levels of physical activity.

"This points to another possible intervention to lower blood pressure," said Paul Elliott, Ph.D., senior author and professor in the Department of Epidemiology and Biostatistics in the School of Public Health at Imperial College London. "These findings lend support for recommendations to reduce the intake of sugar-sweetened beverages, as well as added sugars and sodium in an effort to reduce blood pressure and improve cardiovascular health."

In INTERMAP, researchers analyzed consumption of sugar-sweetened drinks, sugars and diet beverages in 2,696 participants, 40- to 59-years-old, in eight areas of the United States and two areas of the United Kingdom. Participants reported what they ate and drank for four days via in depth interviews administered by trained observers, underwent two 24-hour urine collections, eight blood pressure readings and responded a detailed questionnaire on lifestyle, medical and social factors.

The researchers found that sugar intake in the form of glucose, fructose and sucrose was highest in those consuming more than one sugar-sweetened beverage daily. They also found that individuals consuming more than one serving per day of sugar-sweetened beverages consumed more calories than those who didn't, with average energy intake of more than 397 calories per day.

Those who did not consume sugar-sweetened beverages had lower average body mass index (BMI) than those who consumed more than one of these drinks daily.

"People who drink a lot of sugar-sweetened beverages appear to have less healthy diets," said Ian Brown, Ph.D., research associate at Imperial College London. "They are consuming empty calories without the nutritional benefits of real food. They consume less potassium, magnesium and calcium.

"One possible mechanism for sugar-sweetened beverages and fructose increasing blood pressure levels is a resultant increase in the level of uric acid in the blood that may in turn lower the nitric oxide required to keep the blood vessels dilated. Sugar consumption also has been linked to enhanced sympathetic nervous system activity and sodium retention."

The study's limitations include that it was cross-sectional and diet was self-reported.

"This is a population study. It's one piece of the evidence in a jigsaw puzzle that needs to be completed," Brown said. "In the meantime, people who want to drink sugar-sweetened beverages should do so only in moderation."

The American Heart Association recommends no more than half of the discretionary calorie allowance from added sugars, which for most American women is no more than 100 calories per day and for most American men no more than 150 calories per day. Discretionary calories are the remaining calories in a person's "energy allowance" after consuming the recommended types and amounts of foods to meet all daily nutrient requirements.

Co-authors are: Jeremiah Stamler, M.D.; Linda Van Horn, Ph.D., R.D.; Claire E. Robertson, Ph.D., R.Nutr.; Queenie Chan, M.Sc.; Alan R. Dyer, Ph.D.; Chiang-Ching Huang, Ph.D.; Beatriz L. Rodriguez, M.D., Ph.D.; Liancheng Zhao, M.D.; Martha L. Daviglus, M.D., Ph.D.; Hirotsugu Ueshima M.D., Ph.D.; and Paul Elliott, Ph.D. Author disclosures are on the manuscript.

The National Heart, Lung, and Blood Institute, National Institutes of Health, Chicago Health Research Foundation and national agencies in China, Japan and the United Kingdom funded the study.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Heart Association.

Journal Reference:

Ian J. Brown, Jeremiah Stamler, Linda Van Horn, Claire E. Robertson, Queenie Chan, Alan R. Dyer, Chiang-Ching Huang, Beatriz L. Rodriguez, Liancheng Zhao, Martha L. Daviglus, Hirotsugu Ueshima, Paul Elliott, and for the International Study of Macro/Micronutrients and Blood Pressure Research Group. Sugar-Sweetened Beverage, Sugar Intake of Individuals, and Their Blood Pressure: International Study of Macro/Micronutrients and Blood Pressure. Hypertension, February 28, 2011 DOI: 10.1161/HYPERTENSIONAHA.110.165456

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Whey supplements lower blood pressure: Low-cost protein gets big results in people with elevated blood pressure

ScienceDaily (Dec. 13, 2010) — Beverages supplemented by whey-based protein can significantly reduce elevated blood pressure, reducing the risk of stroke and heart disease, a Washington State University study has found.

Research led by nutritional biochemist Susan Fluegel and published in International Dairy Journal found that daily doses of commonly available whey brought a more than six-point reduction in the average blood pressure of men and women with elevated systolic and diastolic blood pressures. While the study was confined to 71 student subjects between the ages of 18 and 26, Fluegel says older people with blood pressure issues would likely get similar results.

"One of the things I like about this is it is low-cost," says Fluegel, a nutritional biochemistry instructor interested in treating disease through changes in nutrition and exercise. "Not only that, whey protein has not been shown to be harmful in any way."

Terry Shultz, co-author and an emeritus professor in the former Department of Food Science and Human Nutrition, said the findings have practical implications for personal health as well as the dairy industry.

"These are very intriguing findings, very interesting," he said. "To my knowledge, this hasn't been shown before."

The study, which Fluegel did for her doctorate in nutritional biochemistry, notes that researchers in a 2007 study found no blood-pressure changes in people who took a whey-supplemented drink. At first, she saw no consistent improvement either. But then she thought to break out her subjects into different groups and found significant improvements in those with different types of elevated blood pressure. Improvements began in the first week of the study and lasted through its six-week course.

The supplements, delivered in fruit-flavored drinks developed at the WSU Creamery, did not lower the blood pressure of subjects who did not have elevated pressure to begin with. That's good, said Fluegel, as low blood pressure can also be a problem.

Other studies have found that blood-pressure reductions like those seen by Fluegel can reduce cardiovascular disease and bring a 35 to 40 percent reduction in fatal strokes.

Health benefits aside, researchers are excited about the prospect of improving the market for whey, a cheese byproduct that often has to be disposed of at some expense. Its potential economic impact is unclear, says Shannon Neibergs, a WSU extension economist, "but any positive use of that product is going to be beneficial."

Several supplement makers contributed product to the study, which was funded in part by the Washington Dairy Products Commission. None of the contributors had a role in analyzing the data or writing the report.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Washington State University.

Journal Reference:

Susan M. Fluegel, Terry D. Shultz, Joseph R. Powers, Stephanie Clark, Celestina Barbosa-Leiker, Bruce R. Wright, Timothy S. Freson, Heidi A. Fluegel, Jonathan D. Minch, Lance K. Schwarzkopf. Whey beverages decrease blood pressure in prehypertensive and hypertensive young men and women. International Dairy Journal, 2010; 20 (11): 753 DOI: 10.1016/j.idairyj.2010.06.005

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Blood pressure breakthrough holds real hope for treatment of pre-eclampsia

ScienceDaily (Oct. 7, 2010) — Scientists have discovered a mechanism which raises blood pressure in pre-eclampsia, a potentially deadly condition which occurs during pregnancy.

After 20 years of research, scientists from the University of Cambridge have now cracked the first step in the main process that controls blood pressure. Their findings, published in the journal Nature, are likely to have significant implications for the treatment of pre-eclampsia as well as high blood pressure (also known as hypertension).

Blood pressure is controlled by hormones called angiotensins, which cause the blood vessels to constrict. These hormones are released by the protein angiotensinogen. Until now, it was not understood how this occurred.

Dr Aiwu Zhou, a British Heart Foundation (BHF) Fellow at the University of Cambridge, who made the breakthrough, said: "Although we primarily focused on pre-eclampsia, the research also opens new leads for future research into the causes of hypertension in general."

To make the discovery, the researchers solved the structure of angiotensinogen with the help of an extremely intense X-ray beam produced by Diamond Light Source, the UK synchrotron. Their results revealed that the protein is oxidised and changes shape to permit ready access to angiotensinogen by an enzyme, renin. Renin cuts off the tail of the protein to release the hormone angiotensin, which then raises blood pressure.

Taking their lab results into the clinic at the University of Nottingham, the research team showed that the amount of oxidised, and hence more active, angiotensinogen was increased in women with pre-eclampsia.

Professor Robin Carrell at the University of Cambridge, who led the 20-year research project, explained: "During pregnancy oxidative changes can occur in the placenta. These changes, the very ones we have found stimulates the release of the hormone angiotensin and lead to increased blood pressure, can arise as the circulation in the placenta readjusts the oxygen requirements of the growing foetus with the delivery of oxygen to the placenta from the mother."

Drugs currently used to treat high blood pressure -- such as ACE inhibitors -- focus on the later stages of the mechanism that controls blood pressure. The latest findings, which give insight into the previously mysterious early stages of the regulation process, provide scientists with new opportunities to research novel treatments for hypertension.

Professor Peter Weissberg, Medical Director of the BHF, which largely funded the study, said: "Every year in the UK pre-eclampsia is responsible for the deaths of around six women and several hundred babies. This research is of the highest quality and offers real hope for developing strategies to prevent or treat this dangerous condition by targeting the process that these scientists have identified. And of course, although the researchers only looked at pre-eclampsia in this study, similar strategies may be useful for those people with high blood pressure that is not effectively controlled by current medicines."

High blood pressure frequently affects pregnancy. However, in 2-7 per cent of pregnancies this develops into pre-eclampsia, which threatens the health and survival of both the mother and child. In Britain, it affects about one in 20 women during pregnancy, and every year 50,000 women and 500,000 infants die globally as a result of pre-eclampsia. There is no treatment for pre-eclampsia and often the mother is either induced early or undergoes a Caesarean.

The research was largely funded by the British Heart Foundation, with additional funding provided by the Medical Research Council, the Wellcome Trust and the Isaac Newton Trust.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Cambridge, via EurekAlert!, a service of AAAS.

Journal Reference:

Aiwu Zhou, Robin W. Carrell, Michael P. Murphy, Zhenquan Wei, Yahui Yan, Peter L. D. Stanley, Penelope E. Stein, Fiona Broughton Pipkin, Randy J. Read. A redox switch in angiotensinogen modulates angiotensin release. Nature, 2010; DOI: 10.1038/nature09505

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Lower blood pressure may preserve kidney function in some patients

ScienceDaily (Sep. 2, 2010) — Intensively treating hypertension in some African Americans with kidney disease by pushing blood pressure well below the current recommended goal may significantly decrease the number who lose kidney function and require dialysis, suggests a Johns Hopkins-led study publishing in the New England Journal of Medicine.

"This is not a panacea. We have a lot more to figure out. But our evidence suggests that we have a way to at least delay or possibly even prevent end-stage kidney disease in some patients," says Lawrence J. Appel, M.D., M.P.H., a professor of medicine at the Johns Hopkins University School of Medicine and the study's leader.

End-stage kidney disease is the point at which patients need to be on dialysis or receive a kidney transplant in order to survive.

Still, not everyone in the study was helped by the aggressive blood pressure treatment. Those patients who had little or no protein in their urine -- that is, patients who were not as sick -- saw their kidney disease progress at roughly the same rate regardless of how low they tried to get their blood pressure. It was the sicker patients, that is, those with protein in their urine, who benefited most from the more intensive blood pressure therapy, with roughly a 25 percent reduction in end-stage kidney disease as compared with those who met the standard blood pressure goal. Roughly one-third of the participants had higher amounts of protein in their urine.

"This has always been a hot topic: Is a lower blood pressure goal better at preserving kidney function than the standard goal? The answer is a qualified yes, notably in people who have some protein in their urine," Appel says.

In the National Institutes of Health-sponsored African-American Study of Kidney Disease and Hypertension (AASK), 1,094 hypertensive African Americans with chronic kidney disease were randomized to one of two groups: standard blood pressure goal versus intensive (or lower) blood pressure goal. Both groups needed to get their blood pressure in check -- the first group's goal was a blood pressure of roughly 140/90 (the standard target of doctors when treating hypertensive patients), while the second group's goal was approximately 130/80. Researchers lowered blood pressure through a combination of commonly used drugs. The patients were followed between 8.8 and 12.2 years.

Chronic kidney disease is a major public health problem and one that is only growing, Appel says. In the United States, roughly one-third of cases of end-stage kidney disease -- in which the kidneys no longer function and patients require dialysis or a transplant -- are attributed to hypertension. The burden of kidney disease is especially high in African Americans. Though they constitute only 12 percent of the population, African Americans make up 32 percent of those with end-stage kidney disease. Appel says African Americans are four to 20 times more likely to reach end-stage kidney disease, though researchers remain unsure of the reasons why.

Physicians consider patients with blood pressure over 140/90 to be hypertensive, and they will often put those patients on blood pressure-lowering medication with the goal of getting them back below that hazardous threshold. In recent years, some doctors have suggested that their patients with kidney disease try to get their blood pressure lower than that to stave off the progression of kidney disease, though without much scientific evidence, Appel says.

Appel says his study suggests that physicians should check for protein in the urine before determining the blood pressure goal for African Americans with kidney disease. If the patient has protein in the urine, a lower blood pressure goal has the potential to slow the progression of kidney disease. But if the patient has little or no protein in the urine, Appel says, the study suggests that reaching the lower blood pressure goal is not worth the extra effort, and the standard goal is just as good. Getting hypertensive patients down to 130/80 takes more doctor visits and requires more medication -- on average, one more blood pressure prescription. However, once the lower blood pressure level is achieved, keeping the blood pressure there is not particularly difficult.

Even though the study found a benefit of aggressive blood pressure treatment in one group of hypertensive African Americans with kidney disease, a significant number of those patients still ended up with end-stage kidney disease or worse. While roughly 90 percent of those who were in the standard blood pressure group saw their disease progress, about 75 percent of those in the aggressive therapy arm of the trial still progressed to a poor outcome.

"That's still pretty high," Appel says. "The key is preventing early kidney damage in the first place."

More research is necessary, he says, to identify more factors that prevent early kidney damage, as well as factors that delay kidney disease progression among those who already have chronic kidney disease.

The study was conducted at 20 medical centers in the United States. Along with Appel, other Johns Hopkins faculty and staff involved in the research include Edgar Miller, M.D., Ph.D., Brad Astor, Ph.D., M.P.H., M.S.; Charalett Diggs, R.N.; Jeanne Charleston, R.N.; and Charles Harris.

The National Institutes of Health was the primary sponsor of the study. In addition, King Pharmaceuticals provided financial support and donated antihypertensive medications. Pfizer Inc., AstraZeneca Pharmaceuticals, Glaxo Smith Kline, Forest Laboratories, Pharmacia and Upjohn also donated medication.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Johns Hopkins Medical Institutions, via EurekAlert!, a service of AAAS.

Journal Reference:

Appel et al. Intensive Blood-Pressure Control in Hypertensive Chronic Kidney Disease. New England Journal of Medicine, 2010; 363 (10): 918 DOI: 10.1056/NEJMoa0910975

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Common antibiotics and blood pressure medication may result in hospitalization

ScienceDaily (Jan. 18, 2011) — Mixing commonly used antibiotics with common blood pressure medications may cause hypotension (abnormally low blood pressure) and induce shock in older patients, requiring hospitalization, according to a study published in CMAJ (Canadian Medical Association Journal).

"Macrolide antibiotics (erythromycin, clarithromycin and azithromycin) are among the most widely prescribed antibiotics, with millions of prescriptions dispensed in Canada each year." writes Dr. David Juurlink, Scientist at the Sunnybrook Research Institute and the Institute for Clinical Evaluative Sciences with coauthors. "The drugs are generally well-tolerated, but they can cause several important drug interactions."

This study was conducted among Ontarians 66 years and older who were treated with a calcium-channel blocker (drugs often used to treat high blood pressure) between 1994 and 2009. The researchers then identified those who were hospitalized for low blood pressure and, in that group, whether or not a macrolide antibiotic had been prescribed shortly beforehand.

The researchers identified 7100 patients hospitalized for low blood pressure or shock while taking a calcium channel blocker. Treatment with erythromycin was found to increase the risk of low blood pressure almost 6-fold, while clarithromycin increased the risk almost 4-fold. In contrast, azithromycin did not increase the risk of hypotension.

"In older patients receiving calcium channel blockers, the two macrolide antibiotics erythromycin and clarithromycin are associated with a major increase in the risk of hospitalization for hypotension," conclude the authors. "However, the related drug azithromycin appears safe. When clinically appropriate, it should be used preferentially in patients receiving a calcium channel blocker."

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Canadian Medical Association Journal, via EurekAlert!, a service of AAAS.

Journal Reference:

Alissa J. Wright, Tara Gomes, Muhammad M. Mamdani, John R. Horn and David N. Juurlink. The risk of hypotension following co-prescription of macrolide antibiotics and calcium-channel blockers. CMAJ, 2011; DOI: 10.1503/cmaj.100702

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Children with high blood pressure more likely to have learning disabilities, study finds

ScienceDaily (Nov. 10, 2010) — Children who have hypertension are much more likely to have learning disabilities than children with normal blood pressure, according to a new University of Rochester Medical Center (URMC) study published in the journal Pediatrics. In fact, when variables such as socio-economic levels are evened out, children with hypertension were four times more likely to have cognitive problems.

"This study also found that children with hypertension are more likely to have ADHD (attention deficit hyperactivity disorder)," said Heather R. Adams, Ph.D., an assistant professor of Neurology and Pediatrics at URMC, and an author of the study. "Although retrospective, this work adds to the growing evidence of an association between hypertension and cognitive function. With 4 percent of children now estimated to have hypertension, the need to understand this potential connection is incredibly important."

Among the study's 201 patients, all of whom had been referred to a pediatric hypertension clinic at URMC's Golisano Children's Hospital, 101 actually had hypertension, or sustained high blood pressure, determined by 24-hour ambulatory monitoring or monitoring by a school nurse or at home. Overall, 18 percent of the children had learning disabilities, well above the general population's rate of 5 percent. But the percentage among those without hypertension was closer to 9 percent, and among those with hypertension, the rate jumped to 28 percent. All of the children were between 10- and 18-years-old, and the children's learning disability and ADHD diagnoses were reported by parents.

This study is part of a series of hypertension studies by Golisano Children's Hospital researchers, led by Principal Investigator Marc Lande, M.D., a pediatric nephrologist, but it was the first that included children with ADHD. Previous studies excluded them because ADHD medications can increase blood pressure. Researchers included them this time because, although it is possible that some of the children's hypertension was caused by medications, it is also possible that the higher rate of ADHD among children with hypertension is a reflection of neurocognitive problems caused by hypertension. Twenty percent of the children with hypertension had ADHD whereas only 7 percent of those without hypertension had ADHD among the study participants. And even when ADHD was factored out of the analyses, there was still a higher rate of learning disabilities in the hypertensive, compared to the non-hypertensive group of children.

"With each study, we're getting closer to understanding the relationship between hypertension and cognitive function in children," Lande said. "And this study underscores the need for us to continue to tease out the potential risk children with hypertension have for learning difficulties at a time when learning is so important. It may be too early to definitively link hypertension and learning disabilities, but it isn't too early for us, as clinicians, to ensure our pediatric patients with hypertension are getting properly screened for cognitive issues."

The study was funded by a grant from the National Institutes of Health. The authors have no conflicts to disclose.

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The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Rochester Medical Center.

Journal Reference:

H. R. Adams, P. G. Szilagyi, L. Gebhardt, M. B. Lande. Learning and Attention Problems Among Children With Pediatric Primary Hypertension. Pediatrics, 2010; DOI: 10.1542/peds.2010-1899

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