In this memo from a newsletter of the West Meria Public Health Council, the author recommends that it is a good way to prevent cold and absenteeism by daily using Ichthaid(IC), which is a nutritional supplement derived from fish. To support this conclusion he points out that cold is the main reason given for absenteeism and eating fish can effectively prevent cold. He also provide a study reporting the neighboring city East Meria(EM)’s number of people who visit the doctor for cold is very low due to the high fish consumption. However, the evidence lends little credible support for the argument. To begin with, the fact that people in EM rarely visit doctor for the treatment of colds doesn’t indicate a low incidence of colds. Not everyone uncomfortable would visit the doctor. There is naturally the possibility that majority of cold patients prefer staying at home to recover. As cold is a popular case, it is unnecessary to visit the doctor every time. Thus, the number of people visiting the doctor for colds treatment and the low incidence of colds might have no logic relationship.
Moreover, the author fails to establish a causal relationship between high level of fish consumption and the low incidence of cold in EM. It is entirely possible that other conditions mainly contribute to the low incidence of cold rather than eating fish. For example, the climate in EM might be agreeable and pleasant so as to low incidence of cold. Or perhaps, the daily recipe of EM’s residents has some other particular things which have the effect to defend cold. Without roling out these possibilities, the author cannot confidently arrive the conclusion that the low incidence of cold is the result of high fish consumption
Even if the evidence mentioned above is true, the ground evidence that IC can replace eating fish is not guaranteed. IC may not have the same function in preventing colds as has eating fish. After all, the manufacture of the produce IC is a process of refining. Even fish has the function to defend cold, it does not mean that the component of fish like IC has the same effect. The author does not provide any information that the component preventing cold is in IC, I can hardly be convinced that IC is a good choice for defending colds
In sum, the recommendation is not well supported. To strengthen it, the author should ensure that high level of fish consumption and low incidence in EM have causal relationship. To better support it, the author must provide more information of IC