Real cure or placebo?
Professor Plum has a cold. That means that any adventurous textures and flavours are probably going to be a waste of time in her current condition. There is no real cure for the common cold, but there are a number of foods, from garlic to lemon to ginger, that are often recommended to help people get a little bit better. So, I decided to have a go at seeing whether I could cook up anything that would get Plum over her cold.
If there’s one food that’s known above all others to be good for a cold then it’s chicken soup. A Canadian cook of Thai food has been cited as saying: “It must be its soothing smell which makes it appear therapeutic to mothers of all persuasions. Jewish, Mexican, Greek, Canadian — all mothers agree that whatever is wrong with their kids will be put right with a bowl of chicken soup.”
It’s this universality of pro-chicken soup discourse that aroused the interest of Dr. Stephen Rennard, a pulmonary disease expert at the University of Nebraska, back in the 1990s. Interestingly, on top of his medicinal expertise in lung complaints, Rennard also had a background in comparative folklore, having an AB in Folklore and Mythology from Harvard University on top of his medical doctorate.
The earliest references to chicken soup as a cold remedy come from the Egyptian Jewish philosopher-physician Maimonides (Moshe ben Maimon) in the 12th century. Although it is strongly associated with Jewish culture since that point, there are examples of the chicken soup cure in cultures outside the direct sphere of influence of the Mediterranean Jewish community. This is where Rennard’s crossover interest in folklore and medicine came in handy. The idea of “multiple independent discoveries” of chicken soup as a cure in multiple cultures suggested to Rennard that there may be something genuinely effective to discover, rather than just an old wives tale passed down through generations. So, he decided to test the theory.
In 1993 Rennard conducted a laboratory study of the potential medical effectiveness of chicken soup and, in 2000, he published an article on the subject in CHEST, the peer-reviewed medical journal of the American College of Chest Physicians. Rennard’s paper, entitled Chicken Soup Inhibits Neutrophil Chemotaxis In Vitrio, is both slightly jokey and yet remains the leading work of genuine research on the subject. The New York Times cites a piece of research that suggested hot fluids help increase the flow of nasal mucus and chicken soup more than hot water, but still refers mostly to Rennard’s study even years later.
Like most families, Rennard’s had an old reliable family favourite chicken soup recipe to fall back on, or rather Mrs. Rennard did. The doctor’s wife is a good example of how such recipes have been passed through generations of women and contributed a chicken soup recipe of her Lithuanian grandmother to be used for the study. Rennard used his grandma-in-law’s soup and a variety of commercially produced alternatives to test specifically whether chicken soup had any effect in mitigating inflammation.
“Colds are generally the result of transient infections of the mucosa of the upper respiratory tract,” Rennard writes in his paper, “While incompletely understood, the viral infection leads to the stimulation of a cytokine cascade. It is likely that many, if not most, of the symptoms related to colds are consequent to the inflammatory response thus initiated. The activation of common physiologic pathways likely accounts for the marked similarity of symptoms that result from colds. In this regard, colds are associated with the generation of neutrophil chemotactic activities and with the recruitment of neutrophils to the epithelial surface of the airways.”
To break that down into more understandable terms for the non-medically trained among us: neutrophils are the most abundant of the white blood cells, chemotaxis is the term for the movement of cells (taxis) in response to chemical stimuli. In this case it’s this chemotaxis that is one possible cause for how such infections lead to coughs and sneezes. Rennard theorised, therefore, that if chicken soup inhibited this chemotaxis, the movement of neutrophil cells, then it would reduce the unpleasant symptoms and he decided to measure the neutrophils from the blood of student volunteers to test this.
Rennard added the chicken soup to a chemotaxis chamber along with Zymosan-activated serum (ZAS), a chemoattractant that would make the neutrophils migrate towards it. As this graph from Rennard’s paper shows, the chicken soup did indeed inhibit chemotaxis in the neutrophils and did so more based on the concentration of the soup. In case you’re wondering which shop bought chicken soups might be best for your cold, Rennard also tested the neutrophil chemotactic activity relating to a variety of these.
What does all this actually mean in terms of chicken soup’s incredible cold fighting powers, then? Well, as a peer-reviewed scientific paper Rennard’s article is heavily couched in “might”s and “may”s. While his experiment showed an impact from chicken soup on neutrophil chemotaxis, it is only possible that this would really reduce inflammation as it is just part of a much wider variety of inflammatory responses.
Rennard does add, however, that the possible benefits of chicken soup go beyond simply what his study tested. “The warm liquid, particularly when sipped, can stimulate nasal clearance and may improve upper respiratory tract symptoms,” he wrote, “he social setting in which chicken soup is often taken is likely to contribute to a strong placebo effect”. It is probably that these socio-enviromental factors have at least as much to do with the efficacy of chicken soup as a cold cure as any anti-inflammatory qualities. It is the accepted knowledge that chicken soup has a positive effect colds that continues to ensure thhat it does have a positive effect. Like all successful placebos it is self-perpetuating.
The University of Nebraska continue to be keen on media interest in the Rennard study and have posted this video to YouTube of Dr. and Mrs. Rennard preparing the soup, which is perhaps the most twee thing ever to be associated with a serious medical study. Particular highlights are the little women decorating Dr. Rennard’s braces (are a tie and braces good kitchen attire?) and Mrs. Rennard’s Macbeth quoting apron.
Having read the study and watched the video I knew that if I was going to try and cold curing chicken soup recipe on Professor Plum then it should be just the same as Mrs. Rennard’s Lithuanian grandmother. So, that’s just what I did.
Rennard’s study admits that there are some slightly unusual elements about “Grandma’s soup”, which perhaps make it an odd choice for a sort of every-soup for a study like this. There is a heavy root vegetable content, including sweet potato, which Rennard notes as unusual in a chicken soup recipe. He also suggests that the recipe’s depression era origins may account for the method in which the vegetables are pureed and then added to the soup, making it quite thick compared to a soup where the vegetables are removed from the broth prior to serving (although Rennard seems to feel this texture of soup is somewhat more unusual than it actually is).
The result of these methods on my soup, however, was to create a finished product wherein the sweet potato flavour stood out as much stronger than the others, including the chicken. Given Professor Plum’s sense of taste and smell was somewhat impaired, she could taste little beyond the sweet potato, which is not a favourite vegetable of hers, so perhaps the Rennard chicken soup was not ideal in providing a comforting flavour for her palate in particular.
I did depart from the recipe at the final point when serving the soup. In place of the Matzo balls (a sort of Jewish dumpling) that Mrs. Rennard and her grandmother suggest serving with the soup, I made some crusty garlic and herb bread. Firstly because I just like baking bread and prefer bread with soup and secondly because of the apparent cold curing effects of garlic and, oddly, toast.
Apart from the slight excess of sweet potato flavour over chicken it was a pretty decent soup. But what of the patient? Has Dr. Rennard’s soup suggestion proved his research correct and helped cure Professor Plum? Well, no, frankly. I can’t comment on the chemotaxis of her neutrophils, but simple observation suggested that her cold got no better and, if anything, possibly worse in the time after eating the soup.
In this one example, then, the positive benefits of chicken soup proved negligible. At the same time, shop bought cold medication has also done very little. She has just gradually got over it, as you do with colds and this may cut to the truth of the matter: there is no cure for the common cold, soup is as likely to do you a little bit of good as most medication in this circumstance and is a whole lot tastier, so which would you prefer to be treated with?
Professor Plum in the Dining Room: Well, I’m still ill. Even took the leftovers to work, but no luck. Also, if chicken soup has a placebo effect, it might work better if it tasted more strongly of chicken; the sweet potato overpowered everything else, to the point where I’d have assumed that only chicken stock was used, not actual chicken.