Brain and memory training programs are popular, but they don't work well for everyone, says a Universitiy of Michigan psychologist.
New research by Cindy Lustig, a U-M assistant professor of psychology, and colleague David Bissig, a U-M graduate now at Wayne State University—U-M's University Research Corridor alliance partner—reveals what can help make a training program successful, especially for those older adults who could use the most help. Their findings are published in the August issue of Psychological Science.
Programs claiming to "train your brain" are becoming increasingly popular as baby boomers head into their golden years, the researchers say. Even Nintendo has gotten into the game, with a program designed to lower your brain's "age" with repeated playing.
However, not all of these programs have been shown to work, they say. For those that do work, scientists' understanding of how and why they work is very limited. Worse yet, the older a person is and the less memory ability he or she has before training, the less likely that person is to show benefits.
"The bottom line is that in most memory training programs, the people who likely need training the most—those 80 and older and people with lower initial ability—improve the least," Lustig said.
The researchers, who conducted their studies at Lustig's U-M psychology lab, were able to show that the kinds of strategies people use are related to how much benefit they show from training. Accounting for those strategies can eliminate age and ability differences in training success.
Lustig and Bissig took a memory training program that has been used both with healthy older adults and people in the beginning stages of Alzheimer's disease, and asked what was different about people who showed big benefits from training versus those who showed little or no improvement.
The results of the study suggest that in order to improve memory, one needs not only to work hard, but work smart. People in their 60s and 70s used a strategy of spending most of their time on studying the materials and very little on the test, and showed large improvements over the testing sessions.
By contrast, most people in their 80s and older spent very little time studying and instead spent most of their time on the test. These people did not do well and showed very little improvement even after two weeks of training.
One of their conclusions: What matters for memory—and what seems to change as people get older—is not only how much time we spend on trying to remember something, but where we put our efforts.
"My lab is now working on training people of more advanced age and lower education to use the strategies that our most successful participants used, to see if we can boost the performance of these potentially at-risk groups," Lustig said. "A stitch in time saves nine—and studying at the right time just might save your mind."
Tuesday, August 21, 2007
Tuesday, August 14, 2007
Waist-to-hip ratio better predicts heart risk
Waist-to-hip ratio may better predict cardiovascular risk than body mass index
A tape measure, not just a bathroom scale, may help you better assess your heart disease risk.
In a study to be published in the Aug. 21 issue of the Journal of the American College of Cardiology, investigators at UT Southwestern Medical Center found that people with a larger waist-to-hip ratio may be at increased risk for heart disease. The research evaluates the association between different measures of obesity and the prevalence of arterial disease.
“Our study shows that people who develop fat around the middle have more atherosclerotic plaque than those who have smaller waist-to-hip ratios,” said Dr. James de Lemos, associate professor of internal medicine and senior author of the study. “The risk was the same for both men and women who develop abdominal fat.
Prior studies examining the association between obesity and cardiovascular risk reported varied results for overweight subjects who eventually had clinical cardiovascular events. The patients often were evaluated for obesity on the sole measurement of body mass index (BMI), a weight-to-height ratio commonly used in doctors’ offices to gauge obesity. The UT Southwestern findings, however, suggest that BMI alone might not give a clear enough picture of heart disease risk.
“BMI was used as the primary measure of obesity rather than alternative measures such as waist circumference or waist-to-hip ratio,” said Dr. de Lemos. “The latter measures have demonstrated stronger correlations for cardiovascular risk than BMI.”
In the UT Southwestern study, researchers looked at men and women between the ages of 18 and 65. Nearly 3,000 individuals participated in a total of three medical visits each, which included an in-home health survey, blood and urine collection, and a detailed clinical exam complete with abdominal magnetic resonance imaging and coronary artery calcium scans.
Calcium was more likely to be found in the arteries of patients with the greatest waist-to-hip ratio, the researchers discovered. People with the largest waist-to-hip ratio had a twofold increase in the incidence of calcium deposits — a strong indicator of future cardiovascular ailments including heart attacks.
The prevalence of coronary artery calcium was strongly associated with waist circumference and waist-to-hip ratio in addition to high BMI. Hip circumference alone, however, was not a strong indicator for coronary calcium deposits.
“Fat that accumulates around your waist seems to be more biologically active as it secretes inflammatory proteins that contribute to atherosclerotic plaque buildup, whereas fat around your hips doesn’t appear to increase risk for cardiovascular disease at all,” Dr. de Lemos said. “We think the key message for people is to prevent accumulation of central fat early on in their lives. To do so, they will need to develop lifelong dietary and exercise habits that prevent the development of the ‘pot belly.’”
The research was conducted as part of the Dallas Heart Study, a multiethnic, population-based study of more than 6,000 patients in Dallas County designed to examine cardiovascular disease. The multiyear study aims to gather information to help improve the diagnosis, prevention and treatment of heart disease.
A tape measure, not just a bathroom scale, may help you better assess your heart disease risk.
In a study to be published in the Aug. 21 issue of the Journal of the American College of Cardiology, investigators at UT Southwestern Medical Center found that people with a larger waist-to-hip ratio may be at increased risk for heart disease. The research evaluates the association between different measures of obesity and the prevalence of arterial disease.
“Our study shows that people who develop fat around the middle have more atherosclerotic plaque than those who have smaller waist-to-hip ratios,” said Dr. James de Lemos, associate professor of internal medicine and senior author of the study. “The risk was the same for both men and women who develop abdominal fat.
Prior studies examining the association between obesity and cardiovascular risk reported varied results for overweight subjects who eventually had clinical cardiovascular events. The patients often were evaluated for obesity on the sole measurement of body mass index (BMI), a weight-to-height ratio commonly used in doctors’ offices to gauge obesity. The UT Southwestern findings, however, suggest that BMI alone might not give a clear enough picture of heart disease risk.
“BMI was used as the primary measure of obesity rather than alternative measures such as waist circumference or waist-to-hip ratio,” said Dr. de Lemos. “The latter measures have demonstrated stronger correlations for cardiovascular risk than BMI.”
In the UT Southwestern study, researchers looked at men and women between the ages of 18 and 65. Nearly 3,000 individuals participated in a total of three medical visits each, which included an in-home health survey, blood and urine collection, and a detailed clinical exam complete with abdominal magnetic resonance imaging and coronary artery calcium scans.
Calcium was more likely to be found in the arteries of patients with the greatest waist-to-hip ratio, the researchers discovered. People with the largest waist-to-hip ratio had a twofold increase in the incidence of calcium deposits — a strong indicator of future cardiovascular ailments including heart attacks.
The prevalence of coronary artery calcium was strongly associated with waist circumference and waist-to-hip ratio in addition to high BMI. Hip circumference alone, however, was not a strong indicator for coronary calcium deposits.
“Fat that accumulates around your waist seems to be more biologically active as it secretes inflammatory proteins that contribute to atherosclerotic plaque buildup, whereas fat around your hips doesn’t appear to increase risk for cardiovascular disease at all,” Dr. de Lemos said. “We think the key message for people is to prevent accumulation of central fat early on in their lives. To do so, they will need to develop lifelong dietary and exercise habits that prevent the development of the ‘pot belly.’”
The research was conducted as part of the Dallas Heart Study, a multiethnic, population-based study of more than 6,000 patients in Dallas County designed to examine cardiovascular disease. The multiyear study aims to gather information to help improve the diagnosis, prevention and treatment of heart disease.
Tuesday, August 7, 2007
Soluble fiber lowers bad cholesterol
Soluble fiber -- from beans, some fruits and even coffee -- may help lower low-density lipoprotein (LDL) or “bad” cholesterol and blood sugar and may help protect against heart attack and stroke.
The August issue of Mayo Clinic Health Letter explains how to boost soluble fiber in the diet.
Fiber comes in two forms -- soluble and insoluble. Soluble fiber dissolves in water to form a gel-like material. The recommended daily intake of total fiber for women over age 51 is 21 grams. For men over 51, it’s 30 grams.
Fiber supplements, such as Metamucil, Konsyl and others, can boost soluble fiber intake. A typical dose has 2 to 3 grams. Other good sources include:
-- One-half cup of baked beans, cooked black beans, kidney, lima or navy beans provides about 1 gram of soluble fiber. _-- A pear, peach, plum or orange contains about 1 gram of soluble fiber. _-- An apple, mango, one-half of a grapefruit or one-half cup of blackberries each has about _ gram of soluble fiber. _-- Certain vegetables, such as a medium carrot, one-half cup of cooked peas, broccoli or Brussels sprouts, or a medium cooked potato with its skin, contain about 1 gram of soluble fiber. _-- Oats, whether as one-half cup of oatmeal or oat bran or as an ounce of granola, are good for about 1 gram of soluble fiber. _-- Brewed coffee -- A recent analysis showed a cup of brewed coffee contains about 1 gram of soluble fiber.
The August issue of Mayo Clinic Health Letter explains how to boost soluble fiber in the diet.
Fiber comes in two forms -- soluble and insoluble. Soluble fiber dissolves in water to form a gel-like material. The recommended daily intake of total fiber for women over age 51 is 21 grams. For men over 51, it’s 30 grams.
Fiber supplements, such as Metamucil, Konsyl and others, can boost soluble fiber intake. A typical dose has 2 to 3 grams. Other good sources include:
-- One-half cup of baked beans, cooked black beans, kidney, lima or navy beans provides about 1 gram of soluble fiber. _-- A pear, peach, plum or orange contains about 1 gram of soluble fiber. _-- An apple, mango, one-half of a grapefruit or one-half cup of blackberries each has about _ gram of soluble fiber. _-- Certain vegetables, such as a medium carrot, one-half cup of cooked peas, broccoli or Brussels sprouts, or a medium cooked potato with its skin, contain about 1 gram of soluble fiber. _-- Oats, whether as one-half cup of oatmeal or oat bran or as an ounce of granola, are good for about 1 gram of soluble fiber. _-- Brewed coffee -- A recent analysis showed a cup of brewed coffee contains about 1 gram of soluble fiber.
Diets high in choline = risk for colorectal polyps
Diets high in choline may increase risk for colorectal polyps
Contrary to expectations, diets high in the nutrient choline were associated with an increased risk of some colorectal polyps, which can—but do not always—lead to colorectal cancer, according to a study published online in the August 7 Journal of the National Cancer Institute.
Major food sources of choline include red meat, eggs, poultry, and dairy products. Choline is involved in a biochemical process known as one-carbon metabolism. Studies have shown that people with increased intake of other nutrients required for one-carbon metabolism, such as folate, are at a decreased risk for colorectal polyps. This is the first study to examine the association between choline and colorectal polyps.
Eunyoung Cho, Sc.D., of Brigham and Women’s Hospital in Boston and colleagues sent food-frequency questionnaires to women enrolled in the Nurses’ Health Study every two to four years from 1984 to 2002. They then estimated the choline content in their diets.
The researchers had hypothesized that choline intake would decrease the risk of colorectal polyps like folate does. But the results suggest the opposite—greater amounts of choline in the diet were associated with an elevated risk of colorectal polyps.
“Although our results were contrary to expectation based on choline’s role [in one-carbon metabolism], there is a potential biologic basis for the positive association that we observed…Once a tumor is initiated, growth into a detectable [polyp] depends in part on choline availability because choline is needed to make membranes in all rapidly growing cells,” the authors write. However, because this was the first study of choline and colorectal polyps, and other components of diets high in choline may be responsible for the association, the finding needs to be replicated in other studies.
In an accompanying editorial, Regina Ziegler, Ph.D., and Unhee Lim, Ph.D., of the National Cancer Institute in Bethesda, Md., describe the complexity of the relationship between one-carbon metabolism and the development of cancer.
“Clearly, one-carbon metabolism and its role in [cancer development] is more complicated than originally anticipated, and our understanding of the underlying mechanisms is probably incomplete. More research, and caution in developing public health policy and guidance, is warranted,” the authors write.
Contrary to expectations, diets high in the nutrient choline were associated with an increased risk of some colorectal polyps, which can—but do not always—lead to colorectal cancer, according to a study published online in the August 7 Journal of the National Cancer Institute.
Major food sources of choline include red meat, eggs, poultry, and dairy products. Choline is involved in a biochemical process known as one-carbon metabolism. Studies have shown that people with increased intake of other nutrients required for one-carbon metabolism, such as folate, are at a decreased risk for colorectal polyps. This is the first study to examine the association between choline and colorectal polyps.
Eunyoung Cho, Sc.D., of Brigham and Women’s Hospital in Boston and colleagues sent food-frequency questionnaires to women enrolled in the Nurses’ Health Study every two to four years from 1984 to 2002. They then estimated the choline content in their diets.
The researchers had hypothesized that choline intake would decrease the risk of colorectal polyps like folate does. But the results suggest the opposite—greater amounts of choline in the diet were associated with an elevated risk of colorectal polyps.
“Although our results were contrary to expectation based on choline’s role [in one-carbon metabolism], there is a potential biologic basis for the positive association that we observed…Once a tumor is initiated, growth into a detectable [polyp] depends in part on choline availability because choline is needed to make membranes in all rapidly growing cells,” the authors write. However, because this was the first study of choline and colorectal polyps, and other components of diets high in choline may be responsible for the association, the finding needs to be replicated in other studies.
In an accompanying editorial, Regina Ziegler, Ph.D., and Unhee Lim, Ph.D., of the National Cancer Institute in Bethesda, Md., describe the complexity of the relationship between one-carbon metabolism and the development of cancer.
“Clearly, one-carbon metabolism and its role in [cancer development] is more complicated than originally anticipated, and our understanding of the underlying mechanisms is probably incomplete. More research, and caution in developing public health policy and guidance, is warranted,” the authors write.
Friday, August 3, 2007
Should You Take a Statin?
If your annual checkup reveals that your cholesterol levels are high, your doctor may recommend you take a statin—such as atorvastatin (Lipitor), sim¬va¬statin (Zocor), rosuva¬statin (Crestor), prava¬statin (Pravachol), or lovastatin (Mevacor)—to help lower your “bad” LDL cholesterol. Statins also can slightly raise “good” HDL cholesterol and may help lower triglycerides—blood fats that can increase heart disease risk, according to Weill Cornell Medical College. According to the National Cholesterol Education Program (NCEP) of the National Institutes of Health, 11 million Americans take a statin; another 25 million might benefit from one.
Prevention is key
Heart disease is the number-one killer of women, with stroke not far behind. A recent study of more than 2,700 women (Neurology, Feb. 20, 2007) showed that healthy women with no history of heart disease or stroke but with elevated cholesterol are twice as likely to suffer a stroke than women with lower cholesterol levels.
Antonio M. Gotto, Jr., MD, PhD, dean of Weill Cornell Medical College, says statin drugs are a valuable tool in controlling the cholesterol risk factor. For example, the Cholesterol and Recurrent Events (CARE) study showed that women who were heart disease survivors and took Pravachol instead of placebo did better than men in dodging another heart attack.
“Women overall tend to be at lower risk (for heart disease and stroke), but the studies show statins benefit them,” Dr. Gotto says.
Simeon Margolis, MD, PhD, professor of medicine and biological chemistry at Johns Hopkins School of Medicine in Baltimore, agrees that statins can help women keep cholesterol under control. “Initially, women were not well-represented in the studies,” Dr. Margolis says. “But now there is plenty of evidence that keeping cholesterol levels low prevents heart attack and stroke in women the same as it does in men. Young, old, male, female—it works.”
When to start statin therapy
Roughly half of your cholesterol is manufactured in your liver and other organs, with the rest coming from food sources, such as eggs, dairy products, meat, and poultry. The human body needs a certain amount of cholesterol to produce vital hormones and to manufacture bile salts for the digestion of food. But when cholesterol levels are too high, it can adhere to the walls of arteries to form plaque that blocks the flow of blood.
For women who have not had a heart attack or stroke, the NCEP advocates statins for those with LDL cholesterol of 190 milligrams per deciliter (mg/dl) or higher, even if they are not overweight and don’t have a family history of heart disease or any other risk factor, such as smoking, high blood pressure or diabetes. With two or more other risk factors, an LDL reading of 160 mg/dl or higher might justify a statin, according to the NCEP, with the goal of getting it down to 130 mg/dl.
Dr. Gotto likes to see LDL levels below 100 mg/dl, especially with higher-risk individuals, such as heart attack or stroke survivors or women with diabetes. “I think the guidelines are too high,” he says. And Dr. Margolis acknowledges that some cardiologists like to get LDL levels below 70 in their patients.
In addition to lowering LDL levels, statins also have ancillary benefits: they can relax stiff blood vessels, reduce inflammation (which is thought to be a contributor to heart disease), and inhibit clotting that can lead to heart attack or stroke. A link between statins and the possible prevention of osteoporosis also is being studied, according to Dr. Margolis.
What about side effects?
The most common side effects of statins, such as muscle pain, tend to come with the higher doses, Dr. Margolis says. “They go away if you stop the drug.”
Rather than discontinuing the drug, however, some physicians prescribe a different statin or a different dose to see if that reduces the side effect. A lower dose accompanied by another LDL-lowering drug, ezetimibe (Zetia), may help reduce the risk of developing muscle pain, says Dr. Gotto.
In very rare cases, the inflamed muscles can release a protein that damages the kidneys and can even lead to death. Statins also can cause liver problems in some patients, so make sure your doctor tests your liver function at least once a year.
Some women, such as those in frail physical condition, the very elderly, and those of Asian descent, also may be at greater risk for muscle pain side effects.
Lifestyle changes
What about controlling cholesterol through diet and exercise? The NCEP recommends such steps as part of any treatment. Lifestyle changes can lower cholesterol by up to 15 percent, according to Dr. Margolis, but statins may reduce it by up to 50 percent with few side effects, depending on the statin and the dosage.
Nevertheless, it’s a good idea, even if you are taking a statin, to use oils low in saturated fats, such as olive oil; roast or steam foods instead of frying them; eliminate trans fats from your diet (they increase LDL and lower HDL); use egg whites instead of whole eggs; and load up on complex carbohydrates such as oatmeal, bran, vegetables, and fruits. Aerobic exercise, such as a good walk, on most days of the week is also important.
WHAT YOU SHOULD KNOW ABOUT STATINS
Statins must be taken regularly to maintain lower cholesterol levels and can be expensive, even with insurance.
Statins have been shown to reduce heart attack and stroke in both genders.
Statins can lower LDL cholesterol by up to 50 percent. Lifestyle changes, at best, can lower LDL by up to 15 percent.
Muscle pain is reported in as many as seven percent of those who take statins but may ease with reduced dosage or another type of statin.
Prevention is key
Heart disease is the number-one killer of women, with stroke not far behind. A recent study of more than 2,700 women (Neurology, Feb. 20, 2007) showed that healthy women with no history of heart disease or stroke but with elevated cholesterol are twice as likely to suffer a stroke than women with lower cholesterol levels.
Antonio M. Gotto, Jr., MD, PhD, dean of Weill Cornell Medical College, says statin drugs are a valuable tool in controlling the cholesterol risk factor. For example, the Cholesterol and Recurrent Events (CARE) study showed that women who were heart disease survivors and took Pravachol instead of placebo did better than men in dodging another heart attack.
“Women overall tend to be at lower risk (for heart disease and stroke), but the studies show statins benefit them,” Dr. Gotto says.
Simeon Margolis, MD, PhD, professor of medicine and biological chemistry at Johns Hopkins School of Medicine in Baltimore, agrees that statins can help women keep cholesterol under control. “Initially, women were not well-represented in the studies,” Dr. Margolis says. “But now there is plenty of evidence that keeping cholesterol levels low prevents heart attack and stroke in women the same as it does in men. Young, old, male, female—it works.”
When to start statin therapy
Roughly half of your cholesterol is manufactured in your liver and other organs, with the rest coming from food sources, such as eggs, dairy products, meat, and poultry. The human body needs a certain amount of cholesterol to produce vital hormones and to manufacture bile salts for the digestion of food. But when cholesterol levels are too high, it can adhere to the walls of arteries to form plaque that blocks the flow of blood.
For women who have not had a heart attack or stroke, the NCEP advocates statins for those with LDL cholesterol of 190 milligrams per deciliter (mg/dl) or higher, even if they are not overweight and don’t have a family history of heart disease or any other risk factor, such as smoking, high blood pressure or diabetes. With two or more other risk factors, an LDL reading of 160 mg/dl or higher might justify a statin, according to the NCEP, with the goal of getting it down to 130 mg/dl.
Dr. Gotto likes to see LDL levels below 100 mg/dl, especially with higher-risk individuals, such as heart attack or stroke survivors or women with diabetes. “I think the guidelines are too high,” he says. And Dr. Margolis acknowledges that some cardiologists like to get LDL levels below 70 in their patients.
In addition to lowering LDL levels, statins also have ancillary benefits: they can relax stiff blood vessels, reduce inflammation (which is thought to be a contributor to heart disease), and inhibit clotting that can lead to heart attack or stroke. A link between statins and the possible prevention of osteoporosis also is being studied, according to Dr. Margolis.
What about side effects?
The most common side effects of statins, such as muscle pain, tend to come with the higher doses, Dr. Margolis says. “They go away if you stop the drug.”
Rather than discontinuing the drug, however, some physicians prescribe a different statin or a different dose to see if that reduces the side effect. A lower dose accompanied by another LDL-lowering drug, ezetimibe (Zetia), may help reduce the risk of developing muscle pain, says Dr. Gotto.
In very rare cases, the inflamed muscles can release a protein that damages the kidneys and can even lead to death. Statins also can cause liver problems in some patients, so make sure your doctor tests your liver function at least once a year.
Some women, such as those in frail physical condition, the very elderly, and those of Asian descent, also may be at greater risk for muscle pain side effects.
Lifestyle changes
What about controlling cholesterol through diet and exercise? The NCEP recommends such steps as part of any treatment. Lifestyle changes can lower cholesterol by up to 15 percent, according to Dr. Margolis, but statins may reduce it by up to 50 percent with few side effects, depending on the statin and the dosage.
Nevertheless, it’s a good idea, even if you are taking a statin, to use oils low in saturated fats, such as olive oil; roast or steam foods instead of frying them; eliminate trans fats from your diet (they increase LDL and lower HDL); use egg whites instead of whole eggs; and load up on complex carbohydrates such as oatmeal, bran, vegetables, and fruits. Aerobic exercise, such as a good walk, on most days of the week is also important.
WHAT YOU SHOULD KNOW ABOUT STATINS
Statins must be taken regularly to maintain lower cholesterol levels and can be expensive, even with insurance.
Statins have been shown to reduce heart attack and stroke in both genders.
Statins can lower LDL cholesterol by up to 50 percent. Lifestyle changes, at best, can lower LDL by up to 15 percent.
Muscle pain is reported in as many as seven percent of those who take statins but may ease with reduced dosage or another type of statin.
Thursday, August 2, 2007
Zinc Lozenges an Ineffective Treatment for Colds
Despite 20 years of research, the benefits of zinc lozenges as a therapy for the common cold have not been proven. A new study, published in the Sept. 1 issue of Clinical Infectious Diseases, currently available online, reviews the 14 placebo-controlled studies from the past two decades and finds significant fault with 10 of the studies. Of the four remaining studies, three reported no therapeutic effect from zinc lozenge or nasal spray, and one study reported positive results from zinc nasal gel.
“The best scientific evidence available indicates that zinc lozenges are not effective in treating colds,” said Jack M. Gwaltney, Jr., MD, one of the authors.
With colds affecting virtually everybody (one study estimates that adults experience an average of three colds each year and children may experience as many as eight or 10), people are eager to alleviate the discomfort that accompanies a cold. In 1984, the first study reporting that zinc lozenges effectively reduced the duration of the common cold was published. Many other studies followed, some seeming to support the idea of zinc either lessening symptoms or length of illness and some finding no effect.
In this new research, the authors have sorted through 105 studies of zinc and the common cold. From this, they extracted the 14 randomized, placebo-controlled studies, the type of study that might provide the strongest evidence for or against zinc’s usefulness in cold-relief. They then checked each study for 11 features of experimental design that needed to be met in order for the study to produce valid results.
The research was performed by medical student Thomas Caruso of Stanford University School of Medicine with the direction of Dr. Gwaltney, a professor of internal medicine, emeritus, at the University of Virginia School of Medicine, and with the assistance of Charles Prober, MD, also at Stanford.
They found significant flaws in 10 of the studies, flaws that may have invalidated the results. The most frequently found problem was the lack of an “intent to treat” analysis, which ensures that data for all subjects will be used regardless of whether or not they complete the trial. This is important because if study subjects who are taking zinc decide it’s not having an effect and quit the study, and their data is not included in the analysis, then they might leave behind only those subjects who think the zinc is having an effect, creating a significant bias in favor of the effectiveness of zinc.
Other problems found in the studies included lack of a quantifiable hypothesis or sample sizes too small to produce statistically valid findings.
Of the four studies that met the authors’ criteria, two studies reported that zinc lozenges had no effect on the symptom severity or duration of a cold, one study reported no effect of zinc nasal spray, and one study reported a positive effect of zinc nasal gel in lessening symptoms and length of a cold.
“Since less information is available on the intranasal approach, additional well-designed studies of intranasal zinc spray or zinc-treated nasal swabs should be performed,” said Dr. Gwaltney.
As the search for a cure for the common cold continues, some may be happy to learn that it isn’t contained in a zinc lozenge, as the lozenges are frequently reported to be unpleasant to the taste and may produce stomach ache and nausea as side effects. In addition, chronic zinc intake of greater than 40 mg/day can lead to malfunctioning of the immune system and chronic fatigue (various brands of lozenges have between 5 and 24 mg of zinc in each lozenge).
“The best scientific evidence available indicates that zinc lozenges are not effective in treating colds,” said Jack M. Gwaltney, Jr., MD, one of the authors.
With colds affecting virtually everybody (one study estimates that adults experience an average of three colds each year and children may experience as many as eight or 10), people are eager to alleviate the discomfort that accompanies a cold. In 1984, the first study reporting that zinc lozenges effectively reduced the duration of the common cold was published. Many other studies followed, some seeming to support the idea of zinc either lessening symptoms or length of illness and some finding no effect.
In this new research, the authors have sorted through 105 studies of zinc and the common cold. From this, they extracted the 14 randomized, placebo-controlled studies, the type of study that might provide the strongest evidence for or against zinc’s usefulness in cold-relief. They then checked each study for 11 features of experimental design that needed to be met in order for the study to produce valid results.
The research was performed by medical student Thomas Caruso of Stanford University School of Medicine with the direction of Dr. Gwaltney, a professor of internal medicine, emeritus, at the University of Virginia School of Medicine, and with the assistance of Charles Prober, MD, also at Stanford.
They found significant flaws in 10 of the studies, flaws that may have invalidated the results. The most frequently found problem was the lack of an “intent to treat” analysis, which ensures that data for all subjects will be used regardless of whether or not they complete the trial. This is important because if study subjects who are taking zinc decide it’s not having an effect and quit the study, and their data is not included in the analysis, then they might leave behind only those subjects who think the zinc is having an effect, creating a significant bias in favor of the effectiveness of zinc.
Other problems found in the studies included lack of a quantifiable hypothesis or sample sizes too small to produce statistically valid findings.
Of the four studies that met the authors’ criteria, two studies reported that zinc lozenges had no effect on the symptom severity or duration of a cold, one study reported no effect of zinc nasal spray, and one study reported a positive effect of zinc nasal gel in lessening symptoms and length of a cold.
“Since less information is available on the intranasal approach, additional well-designed studies of intranasal zinc spray or zinc-treated nasal swabs should be performed,” said Dr. Gwaltney.
As the search for a cure for the common cold continues, some may be happy to learn that it isn’t contained in a zinc lozenge, as the lozenges are frequently reported to be unpleasant to the taste and may produce stomach ache and nausea as side effects. In addition, chronic zinc intake of greater than 40 mg/day can lead to malfunctioning of the immune system and chronic fatigue (various brands of lozenges have between 5 and 24 mg of zinc in each lozenge).
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