Wednesday, March 29, 2017

Eating peanuts may lead to supple arteries and healthy hearts


Eating peanuts with a meal may help protect against cardiovascular diseases which can lead to heart attacks and stroke, according to an international team of researchers.

In the study, overweight and obese but otherwise healthy men who ate about three ounces of peanuts with a high-fat meal had a blunted increase of lipids in their bloodstream, said Penny Kris-Etherton, distinguished professor of nutrition, Penn State. She added that previous studies have shown that after a meal, there is a spike in blood lipids; this spike can increase the risk of cardiovascular disease, which is the leading cause of death in the United States, as well as around the world.

"Typically, whenever we eat something, it causes the arteries to get a little bit stiffer during the post-meal period, but we have shown that if you eat peanuts with your meal, this can help prevent the stiffening response," said Kris-Etherton. "When the stiffening response happens in the cells that line the arteries, resulting in decreased elasticity in the arteries, it can limit the availability of nitric oxide, and when there's less nitric oxide, the arteries don't dilate that much. What you want is a dilation of the arteries and for them to be really elastic."

She added that over time, the arterial stiffening response can limit blood flow throughout the body and cause the heart to work harder, increasing the risks of serious cardiovascular problems over time.

"As the heart works harder and harder, over a long period of time, it could lead, ultimately, to heart failure," said Kris-Etherton.

According to the researchers, who report their findings in the current issue of the Journal of Nutrition, eating peanuts can keep the cells that line the arteries healthy, helping them stay more elastic. The researchers showed that when peanuts are eaten with a meal the typical post-meal increase of triglycerides -- a type of fat found in the bloodstream -- is blunted.

"After a meal, triglycerides increase and this typically decreases the dilation of the arteries, but the peanuts prevent that big increase in triglycerides after the meal," said Kris-Etherton. "And that may be the mechanism behind this effect, because the triglycerides are not getting so high, which may explain why there is not a decrease in artery elasticity."

The researchers recruited 15 healthy overweight and obese men for the study. Participants ate a control meal with three ounces of ground unsalted peanuts in the form of a shake. A control group was fed a shake of similar nutritional quantity and quality, but without the peanuts. The researchers took blood samples from the subjects to measure lipid, lipoprotein and insulin levels after 30, 60, 120 and 240 minutes.

An ultrasound machine was used to measure the subjects' blood flow.

According to the researchers, there was a 32 percent reduction in the triglyceride levels after the consumption of the peanut meal compared to the control group.

Three ounces of peanuts is about three times the amount of an average serving size, according to the researchers. Although the peanuts were ground up into a shake for the study, the researchers indicate that just eating peanuts would be expected to cause the same response.

The researchers said that future studies should have more participants and include both men and women.

Tuesday, March 28, 2017

Are tree nut allergies diagnosed too often?


Many patients with a history of a single tree nut allergy are told to avoid all other tree nuts. But is that necessary? If you have a tree nut allergy and were advised to avoid other tree nuts based only on a positive blood or skin prick test, you may not be allergic to the other nuts. New research strongly suggests you should consider having an oral food challenge to properly diagnose additional nut allergies, especially if you've never had a reaction to eating those tree nuts before.
A new study in Annals of Allergy, Asthma and Immunology, the scientific publication of the American College of Allergy, Asthma and Immunology (ACAAI) showed that among people allergic to one nut who have a positive test to other tree nuts, more than half passed an oral food challenge to other tree nuts without a reaction. Passing an oral food challenge means you aren't allergic to that nut. Tree nuts include almonds, cashews, walnuts and hazelnuts, but not peanuts. The study noted that nearly none of the people allergic to peanut, but sensitized to tree nut, were clinically allergic to tree nut. This is the first study indicating that peanut allergic people may not need to avoid all nuts. 
"Too often, people are told they're allergic to tree nuts based on a blood or skin prick test," says allergist Christopher Couch, MD, ACAAI member and lead author of the study. "They take the results at face value and stop eating all tree nuts when they might not actually be allergic. We examined records of 109 people with a known tree nut allergy to an individual nut. They were tested for other tree nuts they had never eaten before using blood or skin prick tests. Despite showing a sensitivity to the additional tree nuts, more than 50 percent of those tested had no reaction in an oral food challenge." 
An oral food challenge is considered the most accurate way to diagnose food allergy. During an oral food challenge, the patient eats tiny amounts of the food in increasing doses over a period of time, followed by a few hours of observation to see if they have a reaction. An oral food challenge should only be conducted under the care of a trained, board-certified allergist. You should never do one on your own since if you are allergic, you could have a severe, life-threatening reaction.
"Previous studies suggested people with a tree nut allergy, as well as those with a peanut allergy, were at risk of being allergic to multiple tree nuts," said allergist Matthew Greenhawt, MD, chair of the ACAAI Food Allergy Committee and study co-author. "We found even a large-sized skin test or elevated blood allergy test is not enough by itself to accurately diagnose a tree nut allergy if the person has never eaten that nut. Tree nut allergy should only be diagnosed if there is both a positive test and a history of developing symptoms after eating that tree nut."
Dr. Greenhawt stressed the study did not include challenges to nuts the individual had a documented history of having a reaction to when eaten. "The practice of avoiding all peanut and tree nuts because of a single-nut allergy may not be necessary," says Dr. Greenhawt. "After an oral food challenge, people allergic to a single tree nut may be able to include other nuts in their diet."

Cookbooks give readers (mostly) bad advice on food safety


A recent study finds that bestselling cookbooks offer readers little useful advice about reducing food-safety risks, and that much of the advice they do provide is inaccurate and not based on sound science.
"Cookbooks aren't widely viewed as a primary source of food-safety information, but cookbook sales are strong and they're intended to be instructional," says Ben Chapman, senior author of a paper on the work and an associate professor of agricultural and human sciences at North Carolina State University.
"Cookbooks tell people how to cook, so we wanted to see if cookbooks were providing any food-safety information related to cooking meat, poultry, seafood or eggs, and whether they were telling people to cook in a way that could affect the risk of contracting foodborne illness," Chapman says.
To that end, the researchers evaluated a total 1,497 recipes from 29 cookbooks that appeared on the New York Times best sellers list for food and diet books. All of the recipes included handling raw animal ingredients: meat, poultry, seafood or eggs.
Specifically, the researchers looked at three things:
  • Does the recipe tell readers to cook the dish to a specific internal temperature?
  • If it does include a temperature, is that temperature one that has been shown to be "safe"? For example, cooking chicken to 165°F.
  • Does the recipe perpetuate food-safety myths - such as saying to cook poultry until the juices "run clear" - that have been proven unreliable as ways of determining if the dish has reached a safe temperature?
    The researchers found that only 123 recipes - 8 percent of those reviewed - mentioned cooking the dish to a specific temperature. And not all of the temperatures listed were high enough to reduce the risk of foodborne illness.
    "In other words, very few recipes provided relevant food-safety information, and 34 of those 123 recipes gave readers information that wasn't safe," Chapman says. "Put another way, only 89 out of 1,497 recipes gave readers reliable information that they could use to reduce their risk of foodborne illness."
    In addition, 99.7 percent of recipes gave readers "subjective indicators" to determine when a dish was done cooking. And none of those indicators were reliable ways to tell if a dish was cooked to a safe temperature.
    "The most common indicator was cooking time, which appeared in 44 percent of the recipes," says Katrina Levine, lead author of the paper and an extension associate in NC State's Department of Agricultural and Human Sciences. "And cooking time is particularly unreliable, because so many factors can affect how long it takes to cook something: the size of the dish being cooked, how cold it was before going into the oven, differences in cooking equipment, and so on."
    Other common indicators used in the cookbooks included references to the color or texture of the meat, as well as vague language such as "cook until done."
    "This is important because cooking meat, poultry, seafood and eggs to a safe internal temperature kills off pathogens that cause foodborne illness," Levine says. "These temperatures were established based on extensive research, targeting the most likely pathogens found in each food."
    A list of safe cooking temperatures can be found at https://www.foodsafety.gov/keep/charts/mintemp.html.
    "Ideally, cookbooks can help us make food tasty and reduce our risk of getting sick, so we'd like to see recipes include good endpoint cooking temperatures," Chapman says. "A similar study was done 25 years ago and found similar results - so nothing has changed in the past quarter century. But by talking about these new results, we're hoping to encourage that change."
  • Which self-help websites actually improve health?


    From depression to weight loss, insomnia to cutting back on alcohol or cigarettes, the Internet teems with sites that promise to help people improve their health.
    Which of these really help - with evidence from gold-standard studies to back up these claims? A new paper compiles only the best of the best: a list of over 40 sites backed by evidence from randomized controlled trials. 
    Website locations for the effective self-help programs are listed at the Journal of Medical Internet Research here: http://www.jmir.org/article/downloadSuppFile/7111/47770
    Compiled by a team at the University of Michigan Medical School, it includes sites that offer people help with reducing their use of alcohol, tobacco and marijuana; managing mental health issues; improving diet and physical activity; and addressing insomnia, chronic pain, cardiovascular risk and childhood health issues. 
    Published in the Journal of Medical Internet Research, the list includes sites that offer more than educational information that help people understand a condition.
    Often, the programs are structured like courses, with stepwise, interactive modules based on psychological principles, and assignments to complete when the user is not on the internet. Some programs take weeks or months to complete. While several sites are free to the general public, others charge a fee. 
    "This list is just a start," says Mary Rogers, Ph.D., a research associate professor at U-M and member of the U-M Institute for Healthcare Policy and Innovation. "New trials are completed on an ongoing basis, so we suspect that there will be additional websites with effective interventions added to this list over time. It is important that procedures are in place so that people know where to find health information that is backed up by science."
    She and her colleagues found that nearly 80 percent of effective online approaches to health-related self-help, shown to work in randomized controlled trials, aren't currently available to the public.
    Rogers and her colleagues hope that their work will help the public in general, but also clinicians who want to steer their patients toward evidence-based online tools to help them between clinic visits.
    About the study
    The investigators started by doing a massive search for research papers in any language, and from any health field, that compiled the evidence from randomized controlled trials for online self-help approaches. They found 71 such papers, called meta-analyses, which looked at the results from 1,733 studies. 
    But through this review, the researchers found that only 21 percent of the online programs had a functioning website after the study was finished. Rogers and her colleagues note that often, the end of a grant to support a trial of an online program means the end of a research team's efforts to provide it. After the trial, ongoing support for web hosting and technical upgrades may not be available. So the authors call for efforts to host such sites after the trials are completed. 
    Many of the websites provide precautionary information to seek professional medical attention for health questions. Some sites also provide resources for health professionals. 
    For example, painACTION which was created using funds from the National Institutes of Health, offers resources for both patients and physicians, and was shown to help patients manage chronic pain. For every four people with chronic back pain who used it, one person experienced improvement compared to a control group. For every three people with migraines who used the site, one person experienced improvement compared to a control. 
    Rogers and her colleagues note that even though the sites on their list have evidence behind them, this does not guarantee a benefit for every single person who uses the site. But, compared to people who don't use the site, they do offer a greater likelihood of a benefit if the program is completed.
    Most of the effective online health programs are available in English but some are available in Spanish, French, Portuguese, Dutch, German, Norwegian, Finnish, Swedish, or Mandarin Chinese. With 3.5 billion Internet users worldwide, future research is necessary to determine whether online programs work equally well in people with different social and cultural backgrounds. 
    Rogers adds, "If there is an internet program that can help someone improve their health and there's little extra cost involved in maintaining it, we should provide more avenues to keep these sites available. It could represent potentially great cost effectiveness globally. In addition, we have to do a better job of letting people know that there are evidence-based sites to help them."
    ###


    The full paper is at  http://www.jmir.org/2017/3/e90/

    Elevated blood pressure not a high mortality risk for elderly with weak grip


     A study of nearly 7,500 Americans age 65 or older suggests that elevated blood pressure is not related to high mortality risk among people in that age group with weak grip strength.
    New research by Oregon State University builds on an earlier OSU study that showed the relationship between high blood pressure and risk of death is largely dependent on elders' frailty status as measured by walking speed.
    The findings are important because they suggest that treating high blood pressure in older patients should not follow a one-size-fits-all approach. When an older person is still functioning at a high level physically, high blood pressure indicates mortality risk; however, when the person is not physically robust, high blood pressure is not a marker for mortality risk.
    "If people are very frail, they typically don't respond well to anti-hypertensive therapy and they are not benefiting from having a low blood pressure," said lead author Chenkai Wu, a graduate student in OSU's College of Public Health and Human Sciences. "The research is basically saying older adults are not one single group, they're very different in terms of their health status, and drugs may not have the same benefits for everyone. This is consistent with the idea of precision medicine, where you don't just look at age, you look at other things like functional status."
    Measured in millimeters of mercury, blood pressure is the force of blood against the vessel walls. Systolic blood pressure, the higher number, is the force during a heartbeat, and diastolic refers to when the heart is at rest.
    Most people's diastolic blood pressure goes down with age. Systolic blood pressure, though, tends to rise, and high blood pressure - hypertension - can put extra strain on the heart and arteries, causing greater risk of heart attack and stroke.
    But as Wu's research suggests, an elderly patient's level of physical functionality should be considered in determining whether anti-hypertensive therapy is warranted.
    Grip strength, easily measured by an inexpensive device known as a dynamometer, is a common way to gauge functionality in the elderly. Another often-used measuring stick is walking speed.
    Wu looked at data from 7,492 people age 65 or older who had taken part in the nationally representative Health and Retirement Study. Six years after being surveyed, 25 percent of those people had died.
    The study showed that elevated systolic blood pressure (150 or greater) and diastolic blood pressure (90 or greater) correlated with a substantially higher likelihood of dying for those with normal grip strength, which is 26 kilograms or more for men and 16 kilograms or more for women.
    "We did three analyses," Wu said. "One was to look at gait speed to separate people into two groups, normal and slow. The second part was grip strength - weak grip and normal grip. Third, we looked at the combinations, and the strongest inverse association between high blood pressure and mortality was for slow walkers with weak grip strength.
    "Both measures are markers of functional status, a multidimensional concept. Considering both might be better than considering each measure alone for identifying subgroups of elders for whom high blood pressure is potentially beneficial."
    OSU public health epidemiologist Michelle Odden, senior author on the study and the lead author on the earlier gait-speed research, explained how high blood pressure might actually help in some cases.
    "As we age, our blood vessels lose elasticity and become stiff," said Odden, an assistant professor in the College of Public Health and Human Sciences. "Higher blood pressure could be a compensatory mechanism to overcome this loss of vascular elasticity and keep fresh blood pumping to the brain and heart.
    "And everyone ages differently - there is a profound difference between the physiological age of an 80-year-old man who golfs every day and someone who needs a walker to get around. So with fast walkers, high blood pressure may be more indicative of underlying disease and not just a symptom of the aging process."
    In addition to the connection with weak grip strength, Wu said there was a "very clear" inverse association between high blood pressure and mortality among those who weren't physically able to finish the gait-speed test in the latest study, measured over a 98.5-inch walk.
    Put another way, among those who couldn't walk a little over 8 feet, high blood pressure was associated with less mortality risk.
    "It's a small group but not negligible - 6 percent - of people who were not able to complete the test," he said. "Compared to grip strength, it's a harder test to complete, an integration of a lot of physiological systems: balance, vision, lower-extremity muscle strength, etc."


    Saturday, March 25, 2017

    Brief interval training three times a week best exercise for aging bodies


    A study published this month in Cell Metabolism, however, suggests that certain sorts of workouts may undo some of what the years can do to our mitochondria.

    Researchers at the Mayo Clinic in Rochester, Minn., recently conducted an experiment on the cells of 72 healthy but sedentary men and women who were 30 or younger or older than 64. After baseline measures were established for their aerobic fitness, their blood-sugar levels and the gene activity and mitochondrial health in their muscle cells, the volunteers were randomly assigned to a particular exercise regimen.

    Some of them did vigorous weight training several times a week; some did brief interval training three times a week on stationary bicycles (pedaling hard for four minutes, resting for three and then repeating that sequence three more times); some rode stationary bikes at a moderate pace for 30 minutes a few times a week and lifted weights lightly on other days. A fourth group, the control, did not exercise.

    After 12 weeks, the lab tests were repeated. In general, everyone experienced improvements in fitness and an ability to regulate blood sugar.

    There were some unsurprising differences: The gains in muscle mass and strength were greater for those who exercised only with weights, while interval training had the strongest influence on endurance.

    But more unexpected results were found in the biopsied muscle cells. Among the younger subjects who went through interval training, the activity levels had changed in 274 genes, compared with 170 genes for those who exercised more moderately and 74 for the weight lifters. Among the older cohort, almost 400 genes were working differently now, compared with 33 for the weight lifters and only 19 for the moderate exercisers.

    Many of these affected genes, especially in the cells of the interval trainers, are believed to influence the ability of mitochondria to produce energy for muscle cells; the subjects who did the interval workouts showed increases in the number and health of their mitochondria — an impact that was particularly pronounced among the older cyclists.

    It seems as if the decline in the cellular health of muscles associated with aging was “corrected” with exercise, especially if it was intense, says Dr. Sreekumaran Nair, a professor of medicine and an endocrinologist at the Mayo Clinic and the study’s senior author. In fact, older people’s cells responded in some ways more robustly to intense exercise than the cells of the young did — suggesting, he says, that it is never too late to benefit from exercise.

    Thursday, March 23, 2017

    Active surveillance preserves quality of life for prostate cancer patients

    Faced with the negative quality-of-life effects from surgery and radiation treatments for prostate cancer, low risk patients may instead want to consider active surveillance with their physician, according to a study released Tuesday by the Journal of the American Medical Association (JAMA).

    The Vanderbilt University Medical Center study led by Daniel Barocas, M.D., MPH, associate professor of Urologic Surgery, compared the side effects and outcomes of contemporary treatments for localized prostate cancer with active surveillance in order to guide men with prostate cancer in choosing the best treatment for them.

    Surgery is considered by some to be the most definitive treatment, and there is evidence from other studies that it has better long-term cancer outcomes than radiation for higher-risk cancers, but it has more sexual and urinary side effects than radiation.

    "Patients who were treated with surgery or radiation had side effects, while those who were managed with active surveillance, for the most part, did quite well," Barocas said.

    "It is best to avoid treatment if you have a prostate cancer that is safe to observe. This is why most doctors recommend 'active surveillance' for low-risk cancers," he said.

    Three-year survival from prostate cancer was excellent in the study at over 99 percent for patients regardless of whether they chose surgery, radiation or active surveillance. Barocas did caution that prostate cancer tends to be slow growing and patients would need to be followed for 10 years or more to find differences in mortality.

    "This study shows that, despite technological advances in the treatment of prostate cancer, both surgery and radiation still have a negative effect on quality of life," said co-author David Penson, M.D., MPH, Paul V. Hamilton, M.D., and Virginia E. Howd Professor of Urologic Oncology and professor and chair of the Department of Urologic Surgery.

    "Certainly, if a man has low-risk prostate cancer, he should seriously be considering active surveillance as a reasonable way to go," he said.

    Erectile dysfunction and urinary incontinence were more common in men treated with surgery than radiation when studied three years after treatment, although the difference in sexual dysfunction was only apparent in patients with excellent baseline function.

    "Urinary incontinence was reported as a moderate or big problem in 14 percent of men three years after surgery compared to 5 percent of men who had radiation," Barocas said.

    "Men who had radiation reported more problems with bowel function and hormone side effects compared to men who had surgery, but these differences were only seen within the first year following treatment," he said.