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TOPIC: ARGUMENT142 - The article entitled 'Eating Iron' in last month's issue of Eating for Health reported that a recent study found a correlation between high levels of iron in the diet and an increased risk of heart disease. Further, it is well established that there is a link between large amounts of red meat in the diet and heart disease, and red meat is high in iron. On the basis of the study and the well-established link between red meat and heart disease, we can conclude that the correlation between high iron levels and heart disease, then, is most probably a function of the correlation between red meat and heart disease.


Outline: 1. 质疑研究中的correlation, 由于研究的样本的可靠性没有被提及， 例如年龄，身体状况，遗传因素。
        2．质疑作者的假设，红肉中的高铁引起心脏病，但可能有其他的因素，例如胆固醇，以及其他矿物质，钙。
       3．质疑结论，the correlation between red meat and heart disease 决定了the correlation between high levels of iron and heart disease, 因为研究中的饮食中的铁可能容易吸收，相对肉中的铁，or 研究中的饮食中的铁来自肝脏，而不是肉类

Before claiming that the correlation between red meat and heart disease causes the correlation between high iron levels and heart disease, a complete examination is needed from several perspectives. The argument assumes that only high levels of iron in red meat result in heart disease without other some possible factors, which may have impaired the credibility of it.

First of all, the reliability and representative of study mentioned by the author is open to doubt. The author does not provide any information about the sample in the study, such as the age, gender, health conditions and genetic features, and so forth. If the majority of persons in study are the older people, then it is entirely possible that their own bad physical condition cause them to more easily suffer from heart disease, not relevant to their high levels of iron in diets. Or if all of persons in study come from the same area where there is generally high incidence of heart disease in group, it is quite likely that these participants in the study natually have a higher risk of heart disease than others at a result of certain genetic accessibility in them to heart disease. Consequently, without considering the cases, the assertion that the high-iron diet in the study leads to heart disease is unreasonable.

Moreover, even if red meat indeed causes heart disease, the assumption that the reason why eating red meat can cause heart disease is due to the high iron levels in it is unwarranted. In fact, there are some possible reasons like cholesterol and calcium involved in red meat, which truly results in heart disease instead of iron in it. As is known to all, meats have high levels of cholesterol. Then it is fully likely that when eating the normal amounts of red meat, people may fully transform the cholesterol and thus the physical fitness cannot be damaged. On the contrary, if people eat a large amount of red meat, the function of transforming cholesterol might have gone the maximum and thus there is a great deal of cholesterol reserving in the body. Eventually, this causes blood vessels of body to thicken and stimulates heart disease. Clearly, under the case, the reason why red meat results in heart disease is not due to its high iron levels.

Finally, the conclusion that the correlation observed in the study is directly relevant to the correlation between red meat and heart disease is not persuasive. Do the high levels of iron in the diet in the study come from red meat? Is the form of iron in red meat same as those in the study? Clearly, the author does not afford any information about these respects. Actually, common sense tells us that the difference with oxidized condition of iron will determine whether it can be absorbed fully. Then it is rather probable that the high levels of iron in diets in the study come from animal liver containing a kind of iron that is the easiest absorbed form, and thus the amounts of iron assimilated stimulate heart disease. However, the iron in red meat is difficult to be absorbed due to the different oxidized form. Thus, the result resting on the study is not relevant to the correlation between red meat and heart disease.

From what has been discussed above, we can safely arrive at the conclusion that the author's contention cannot convince us unless he or she can provide more information about the group of people in study and other possible dangerous factors of red meat causing heat disease.

[ 本帖最后由 aunknown 于 2007-2-1 12:43 编辑 ]