For Cold Virus, Zinc May Edge Out Even Chicken Soup

By TARA PARKER-POPE

From http://well.blogs.nytimes.com/

 

Scientists still haven’t discovered a cure for the common cold, but researchers now say zinc may be the next best thing.

A sweeping new review of the medical research on zinc shows that sniffing, sneezing, coughing and stuffy-headed cold sufferers finally have a better option than just tissue and chicken soup. When taken within 24 hours of the first runny nose or sore throat, zinc lozenges, tablets or syrups can cut colds short by an average of a day or more and sharply reduce the severity of symptoms, according to the Cochrane Database of Systematic Reviews, a respected medical clearinghouse.

In some of the cited studies, the benefits of zinc were significant. A March 2008 report in The Journal of Infectious Diseases, for example, found that zinc lozenges cut the duration of colds to four days from seven days, and reduced coughing to two days from five.

While the findings are certain to send droves of miserable cold sufferers to the drugstore in search of zinc treatments, the study authors offered no guidance on what type of zinc product to buy. The authors declined to make recommendations about the optimal dose, formulation or duration of zinc use, saying that more work was needed before they could make recommendations.

“Over all, it appears that zinc does have an effect in controlling the common cold,” said Dr. Meenu Singh, the review’s lead author and a professor in the department of pediatrics at the Postgraduate Institute of Medical Education and Research in Chandigarh, India. “But there still needs to be consensus about the dose.”
Zinc experts say that many over-the-counter zinc products may not be as effective as those studied by researchers because commercial lozenges and syrups often are made with different formulations of zinc and various flavors and binders that can alter the effectiveness of the treatment.

“A lot of preparations have added so many things that they aren’t releasing zinc properly,” said Dr. Ananda Prasad, professor in the department of oncology at Wayne State University School of Medicine in Detroit and an early pioneer of research into zinc as an essential mineral. Two of Dr. Prasad’s studies were included in the Cochrane report.

“The public is confused because people have used the wrong dose, they have used the wrong sort of zinc or they have not started the treatment within 24 hours of onset,” he said.

Even so, the new report gives credence to the long-debated theory that zinc can be an effective treatment for colds. While it’s not certain how the mineral curbs colds, it appears to have antiviral properties that prevent the cold virus from replicating or attaching to nasal membranes.

The first study to show that zinc might be a useful treatment for the common cold was published in 1984, but the research was criticized for its poor methods. Since that study, 18 more trials of zinc for colds have been conducted: 11 of them showed it to be a useful treatment, while seven of them showed no benefit, according to the review.

Although a majority of trials have shown some benefit from zinc, many of them have been criticized for failing to “mask” the treatment, meaning the participants most likely knew they were using zinc, which may have skewed the results. At the same time, many of the trials that showed no benefit from zinc have been criticized for using formulations that may have contained ingredients that blunted the effectiveness of zinc.

The Cochrane reviewers selected 15 studies that enrolled a combined 1,360 participants. The studies were all considered to have good methodological quality with a low risk of bias, but they were far from perfect. All the studies compared zinc use with a placebo, but in several studies the zinc users complained about the taste of lozenges, suggesting that some people may have known that they were using zinc rather than a placebo.
Even so, when the data was pooled, the effect shown was strong. The review found that not only did zinc reduce the duration and severity of common cold symptoms, but regular zinc use also worked to prevent colds, leading to fewer school absences and less antibiotic use in children. People who used zinc were also far less likely to have a cold that lasted more than seven days.

The studies used various forms and doses of zinc, including zinc gluconate or zinc acetate lozenges and zinc sulfate syrup, and the dose ranged from 30 to 160 milligrams a day. Several studies in the Cochrane review used zinc acetate lozenges from the Web site ColdCure.com, created by George Eby, the researcher who wrote the first zinc study in 1984.

Dr. Prasad said his studies have used zinc acetate lozenges from ColdCure.com that contained about 13 milligrams of zinc. Study participants took a lozenge every three to four hours during the day for four consecutive days, resulting in a daily dose of 50 to 65 milligrams a day, he said.
Some cold sufferers have been wary about using zinc since the Food and Drug Administration warned consumers to stop using Zicam nasal sprays and swabs, which contain zinc, after numerous reports that some users lost their sense of smell after using the product. The Cochrane report did not review any studies of nasal zinc products.

Researchers crack the code of the common cold

Scientists have begun to solve some of the mysteries of the common cold by putting together the pieces of the genetic codes for all the known strains of the human rhinovirus. Researchers at the University of Maryland School of Medicine in Baltimore and colleagues at the University of Wisconsin-Madison have completed the genomic sequences of the viruses and assembled them into a "family tree," which shows how the viruses are related, with their commonalities and differences. The study will be released on the online version of the journal Science (Science Express) at 2 p.m. EST on February 12.

The researchers say this work provides a powerful tool that may lead to the development of the first effective treatments against the common cold.

"There has been no success in developing effective drugs to cure the common cold, which we believe is due to incomplete information about the genetic composition of all these strains," says the study's senior author, Stephen B. Liggett, M.D., professor of medicine and physiology at the University of Maryland School of Medicine and director of its Cardiopulmonary Genomics Program.

"We generally think of colds as a nuisance, but they can be debilitating in the very young and in older individuals, and can trigger asthma attacks at any age. Also, recent studies indicate that early rhinovirus infection in children can program their immune system to develop asthma by adolescence," says Dr. Liggett, who is a pulmonologist and molecular geneticist.

Major discoveries of the study

The researchers found that human rhinoviruses are organized into about 15 small groups that come from distant ancestors. The discovery of these multiple groups explains why a "one drug fits all" approach for anti-viral agents does not work. But, says Dr. Liggett, "Perhaps several anti-viral drugs could be developed, targeted to specific genetic regions of certain groups. The choice of which drug to prescribe would be based on the genetic characteristics of a patient's rhinovirus infection."

Dr. Liggett adds that while anti-viral drugs seem to be the most likely to succeed, "the data gathered from these full genome sequences gives us an opportunity to reconsider vaccines as a possibility, particularly as we gather multiple-patient samples and sequence the entire genomes, to see how frequently they mutate during a cold season. That work is underway now."

The researchers also found that the human rhinovirus skips a step when it makes its protein product, a shortcut that probably speeds up its ability to make a person feel sick soon after infection. "This is a new insight," says co-investigator Claire M. Fraser-Liggett, Ph.D., director of the Institute for Genome Sciences and professor of medicine and microbiology at the University of Maryland School of Medicine. "We would not have had any sort of intuition about this had it not been revealed through genome analysis. Information that comes from this discovery might present a completely different approach in terms of therapy."

The analysis shows that some human rhinoviruses result from the exchange of genetic material between two separate strains of the virus that infect the same person. Such a swap, known as recombination, was previously not thought possible in human rhinovirus. During cold season, when many different strains of rhinovirus may be causing infections, recombination could rapidly produce new strains.

Multiple mutations (as many as 800) were evident in virus samples taken recently from patients with colds, compared to older rhinovirus reference strains. Some viruses mutate by making slight changes in certain proteins to avoid being destroyed by antibodies from a person's immune system. "Mutations were found in every area of the genome," says Dr. Liggett.

The study's lead author, Ann C. Palmenberg, Ph.D., professor of biochemistry and chair of the Institute for Molecular Virology at the University of Wisconsin-Madison, notes, "As we begin to accumulate additional samples from a large number of patients, it is likely that hotspots for mutation or recombination will become apparent, and other regions resistant to mutational change may emerge. This will provide clues as to how flexible the virus is as it responds to the human environment, important hints if you are designing new therapeutics."

Study background

Human rhinovirus infection is responsible for half of all asthma attacks and is a factor in bronchitis, sinusitis, middle ear infections and pneumonia. The coughs, sneezes and sniffles of colds impose a major health care burden in the United States—including visits to health care providers, cost of over-the-counter drugs for symptom relief, often-inappropriate antibiotic prescriptions and missed work days—with direct and indirect costs of about $60 billion annually.

Prior to the start of this project, the genomes of only a few dozen rhinoviruses had been sequenced from what was considered the reference library, a frozen collection of 99 different rhinovirus strains taken from patients over a span of more than two decades. During this team's work, several other groups began to report the full genomes of some of these viruses, as well as some odd rhinovirus-like strains from relatively sick patients.

"It was clear to us that the spectrum of rhinoviruses out there was probably much greater than we realized. Further, we needed to develop a framework from which we could begin to figure out ways to combat these viruses and use their genetic signatures to predict how a specific virus would affect a patient," says Dr. Fraser-Liggett.

The current study adds 80 new full genome sequences to the rhinovirus library and 10 more acquired recently from people with colds. Each sequence was modeled and compared to each other. Dr. Liggett says, "Now we can put together many pieces of the human rhinovirus puzzle to help us answer some fundamental questions: how these rhinoviruses might mutate as they spread from one person to another; which rhinoviruses are more associated with asthma exacerbations and why rhinovirus exposure in infancy may cause asthma later in life. With all this information at hand, we see strong potential for the development of the long-sought cure for the common cold, using modern genomic and molecular techniques."

"With recent improvements in technology, including next-generation DNA sequencing tools, it has become easier to generate whole genome sequence information," says Dr. Fraser-Liggett. "There is no reason any longer to focus on a very limited part of the rhinovirus molecule to learn what it's doing, what the predominant strain is in a population, or to try to infer what the evolution of the entire molecule might be. Instead, by studying the complete genome sequence, we can answer multiple questions in parallel."

Source: University of Maryland Medical Center