I would be embarrassed by this cheap and easy post about chicken soup for symptoms of cold and flu, but I have a more serious purpose. I want to ask ScienceBlogger colleagues who inveigh constantly against alternative medicine (or “woo” as orac at Respectful Insolence insists on calling it) what they think of this and why.
Here’s the set-up:
The suspected benefits of chicken soup were reported centuries ago. The Egyptian Jewish physician and philosopher, Moshe ben Maimonides, recommended chicken soup for respiratory tract symptoms in his 12th century writings which were, in turn, based on earlier Greek writings. But, there’s little in the literature to explain how it works.
In 1993, Stephen Rennard, M.D., conducted an informal laboratory study and submitted the results as an abstract mostly because of its amusement value. Seven years later, his chicken soup research has been officially published in the Oct. 17 issue of CHEST, the peer-reviewed journal of the American College of Chest Physicians. It is titled, “Chicken Soup Inhibits Neutrophil Chemotaxis in vitro.”
Dr. Rennard, Larson Professor of Medicine in the Pulmonary and Critical Care Medicine Section at UNMC [University of Nebraska Medical Center], had for years watched his wife, Barbara, cook her Lithuanian grandmother’s chicken soup recipe when a cold was going around her family of 10.
“She told me the soup was good for colds,” Dr. Rennard said. “I’ve heard that a zillion times. Then I started to think, “well, maybe it has some anti-inflammatory value.” Everyone’s heard this from their mother in many cultures. No one seems to have a monopoly on the insight of the value of chicken soup.”
Three batches of soup prepared in the home of Dr. Rennard were studied in the laboratory under controlled conditions. Researchers collected neutrophils from blood donated by healthy, non-smoking volunteers.
The study focus was to find out if the movement of neutrophils – the most common white cell in the blood that defends the body against infection – would be blocked or reduced by chicken soup. Researchers suspect the reduction in movement of neutrophils may reduce activity in the upper respiratory tract that can cause symptoms associated with a cold.
Colds are the result of infection in the upper respiratory tract, which causes inflammation. Although colds are not completely understood, it is believed the inflammation contributes to cold symptoms. Dr. Rennard theorized if soup can stop or reduce inflammation, it might reduce the symptoms of a cold.
In the laboratory, UNMC scientists diluted the soup and subjected the neutrophils to several variations of the soup, including vegetables, chicken and a combination of the ingredients. The team found the movement of neutrophils were reduced. Samples taken during the initial stages of the soup with chicken broth alone were not found effective in inhibiting neutrophil movement.
The researchers were not able to identify the exact ingredient or ingredients in the soup that made it effective against fighting colds but theorize it may be a combination of ingredients in the soup that work together to have beneficial effects. “All vegetables and the soup had activity,” Dr. Rennard said. “I think it’s the concoction.”
Known as “Grandma’s Soup,” the recipe includes chicken, onions, sweet potatoes, parsnips, turnips, carrots, celery stems, parsley, salt and pepper. For comparison purposes, commercial soups were obtained from a local supermarket and prepared according to the directions on the label. Many of the soups had the same inhibitory effect.
“A variety of soup preparations were evaluated and found to be variably, but generally, able to inhibit neutrophil chemotaxis,” Dr. Rennard said. “The current study, therefore, presents evidence that chicken soup might have an anti-inflammatory activity, namely the inhibition of neutrophil migration.”
Researchers noted that “Grandma’s soup” has several unusual features. It contains strained vegetables. Dr. Rennard noted, however, that the inhibitory activity was observed with several other recipes that lack the particles from vegetables. “Thus,” he said, “while the identity of the biologically active materials is unknown, it seems likely they are water-soluble or extractable. Pureed carrots or other vegetables are not recommended as a remedy while chicken soup is.” (University of Nebraska Medical Center news release)
Chicken soup for flu and colds has to qualify as alternative medicine, I would think. The question I have is this. What would allow it to escape the slings and arrows of Orac’s mighty pen? In perusing his posts on the subject he seems to have two complaints about alternative remedies, which he tends to conflate, often sliding from one to the other. The first is that the treatment has not been shown effective via a Randomized Clinical Trial or other acceptable study design to work. There are some variations on this theme when trials have actually been done. Sometimes critics (not Orac as far as I know) will mistakenly say that the lack of statistical significance in a trial means any effects seen are due to chance (“small numbers” are a variation of this). This, of course, is incorrect but here isn’t the place to go into why. Another response is that the trial is flawed (which many are). So that’s the first complaint: no convincing demonstration of efficacy. Unfortunately much the same can be said for a lot of what we conventional practitioners do. I won’t single out surgeons, but they are hardly free of this millstone (lobotomy, anyone?). OK, I guess I did single out surgeons. Orac is a surgeon.
The second complaint is different: there is no theory or scientific rationale. It is this defect that the present chicken soup “study” seeks to remedy. I’d like to know what Orac and other quack-fighters think. Is this kind of showing sufficient to move chicken soup as therapy out of the alternative camp? If not, how much and what kind of evidence would it take? And what if we have showings of efficacy without any scientific theory? You want an example? We still don’t know how asbestos causes cancer, but on the basis of epidemiological studies we have no doubt that it does. A variation of this is that the proposed explanation is “magical thinking.” That’s perfectly fair as a criticism. Unfortunately, proposed counter-explanations are also vulnerable. If one takes “the placebo effect” to mean an interaction between the mind and the body that produces an effect, that’s at the level of magical thinking in my book. If you provide a neurophysiological explanation that’s fine (assuming you can give one). But then the remedy is actually having a physical effect so what’s the problem? It’s like a psychoactive agent. Counter-irritation as an assumed mechaism is another irritating wave of the hand that seems quite magical to me. What exactly is the mechanism of counter-irritation, say, for acupuncture anesthesia? If you give me one then aren’t you giving me an explanation for how acupuncture really does work? If you can’t, why isn’t that a “magical explanation”? Or is the complaint about some alternative therapies that they might work but have the wrong reason? In which case much of conventional medicine is probably also in big trouble.
Underneath all this are certain difficult epistemological questions, chief among them what philosophers of science call the Demarcation Problem, i.e., criteria that can be used to separate science from pseudoscience. Many scientists think this is settled. Far from it. The two criteria they are likely to give most often, confirmability and falsifiability contradict each other. Moreover both have been abandoned by most contemporary philosophers of science (if they were ever accepted; Popper ruled no philosophical roost but his own). If the criterion is simply “testability” (itself a slippery idea), then astrology is clearly science, not pseudoscience, because it makes testable claims.
I am not raising these questions to rescue any alternative remedies, none of which I use, advocate or believe in, as far as I know. Instead I am trying to bring some humility to the discussion and make a counter claim that a lack of intellectual rigor isn’t confined to one side.
Consider it a gauntlet thrown down to my colleagues. Just for fun.
Oh, I almost forgot. Here’s the recipe for Grandma’s Chicken soup, courtesy nbc6:
Researchers at the University of Nebraska came up with the following recipe, which they say can relieve cold and flu symptoms.
1-5 lb chicken
3 large onions
1 large sweet potato
12 large carrots
6 celery stalks
1 bunch parsley
Salt and pepper to taste
Clean the chicken, put it in a large pot and cover it with cold water. Bring the water to boil. Add the chicken wings, onions, sweet potato, parsnips, turnips and carrots. Boil about 1 and a half hours. Remove fat from the surface as it accumulates. Add the parsley and celery. Cook the mixture about 45 min. longer. Remove the chicken. The chicken is not used further for the soup.
Eat two bowls and go to bed and read me in the morning.