Sunday, December 10, 2006

Eliminating trans fats in Chicago won't eliminate obesity: A cultural perspective concerning access, economics, and causes of obesity - Anna Fendley

The city of Chicago, which is home to almost 3 million Americans, has a fat problem. Among the top five leading causes of death in Chicago in 2005 were heart disease and diabetes (1). These can both be linked to consumption of trans fats. Evidence from epidemiologic studies shows that there is a dose-dependent relationship between trans fat intake and the LDL:HDL cholesterol ratio, which is associated with heart disease and is about twice as great as for saturated fats (2) (3). Trans fats are related to diabetes because their consumption has been shown to cause or exacerbate insulin resistance in people who are overweight (4). Insulin resistance is the characterizing factor in Type 2 diabetes, which accounts for about 90-95% of diabetes cases (4). To alleviate Chicago’s fat problem and the impact of heart disease and diabetes, Edward Burke, a Chicago City Council member, has proposed a ban of trans fats in Chicago restaurants. In an interview with NewsHour on PBS, Burke said, “If the restaurants won't voluntarily change their policy and adopt a healthy means of preparation, then I think that it's clear that municipal government has the right to step in and legislate (5).”

Burke’s proposed ban aligns with recent nation-wide concern about trans fats, which are generally used for deep-frying and preservation. Trans fats are artificially made by partially hydrogenating liquid vegetable oils so the carbon atoms bond in a straight line and the fat remains a solid at room temperature (4). They are calorie-dense and made in very large quantities to be used in margarine, to turn vegetable oils into shortening, to lengthen the shelf-lives of processed foods, and to give a certain feel to fried foods (4). The fat has no safe level according to the American Academy of Sciences (5), however the FDA considers trans fats safe to consume. The proposed ban in Chicago would require restaurants to replace trans fats in their kitchens with other types of oils. Restaurants that do not comply with the regulation would be fined between $200 and $1000 daily (6). Public outcry from small restaurant owners and the Illinois Restaurant Association caused Burke to revise the proposal in July 2006 to include only those restaurants that gross more that $20 million annually (7). These chain restaurants would be the only ones to be investigated and pay the large fines.

This ban as a public health intervention does have positive aspects. For example, it addresses an issue that the public is concerned about, and it takes a societal approach instead of focusing on the individual. However, the ban is unlikely to have a substantial effect in reducing the prevalence of obesity due to the continued access to trans fats, the market economy, and the multiple causes of obesity in the American lifestyle.

The proposed ban of trans fats in Chicago restaurants is not a population-wide intervention and will not significantly reduce access to trans fats for several reasons. First, trans fats are present in many foods that are not affected by the ban in restaurants. There are very few people who eat the majority of their meals in restaurants, and even fewer who eat the majority of their meals in those restaurants that will be affected by this ban. The population at large will still eat trans fats that are in numerous items sold in supermarkets, including margarine and most processed foods because trans fats lengthen their shelf-life by taking a longer time to oxidize than other fats (5) (4). Therefore, many foods, such as cookies and crackers, would not be affected by the restaurant ban and would be readily available to the public.

Second, ease in commuting both into and out of the city suggests that Chicagoans will eat some meals outside of the jurisdiction of the City Council’s proposed ban. The Chicago Transit Authority (CTA) serves a six-county region in the Chicago area. According to its 2005 Annual Budget Summary, the CTA provides 81 percent of the transportation in the region, and ridership has increased for five of the last six years (8). The Summary also reports that 73 percent of the freeways in the area are congested during rush hour (8). This local data suggests that the population in the Chicago area eats and lives both in and outside of Chicago proper. The proposed ban would only significantly reduce access to trans fats for those who primarily eat at large, chain restaurants in the City of Chicago, not for the typical individual who commutes and eats outside of the jurisdiction of the City.

Finally, the proposed ban only affects restaurants in the city that gross over $20 million dollars per year. Smaller restaurants throughout Chicago can continue to use trans fats for frying. Therefore, any Chicagoan who eats fried food at an unaffected restaurant will very likely be consuming trans fats.

Because Chicago’s intervention lacks a population-wide approach to limiting access to trans fats, only a small segment of the population will be affected by the proposed ban. That is, only those people who eat most of their meals large fast-food restaurants will be affected. While the ban could benefit them, access is not limited enough to have a substantial effect on obesity, heart disease, or diabetes.

Another reason that the proposed ban would not eliminate obesity in Chicago is the market economy in which consumers select goods. A market economy allocates resources through decentralized decisions of many producers and consumers as they interact for goods and services (9). According to basic economic principles, the government has a great deal of market power, and its intervention through regulations affects the market of a particular good or service (9). In this example, a ban on trans fats would affect the market for fried food by changing the costs to producers. Oil containing trans fats is significantly cheaper than alternative oils. Before they were exempt from the ban because of yearly gross income, one Chicago pizza restaurant estimated that its costs would increase by $50,000 a year if it was forced to use an alternative oil in its dough(6). However, because the ban only applies to those restaurants that gross more than $20 million a year, these are the only restaurants that will incur the higher costs of production. This high cost must be absorbed by the producer or shared with the consumer by raising prices. If the cost is shared with consumers, the price of food at these restaurants will be higher than at the smaller restaurants that are not affected by the ban. Either way, the producers affected by the ban will lose economic viability because they will lose money, customers or both.

An additional economic principle is that consumers face trade-offs (9). In this case, the trade-off is between foods at a large, chain restaurant whose prices have increased and foods at a smaller restaurant whose prices have stayed the same. Consumers respond to incentives (9). In this situation the incentive is the lower price for foods in the smaller restaurants than in the larger chain restaurants. Finally, rational consumers think at the margin (9) and will choose to be fiscally responsible by purchasing meals at the smaller restaurants with lower prices, regardless of the health costs or benefits.

The situation described here is an example of the outcome of a free market in which consumers choose which goods they purchase. Free markets allocate the demand for goods to the sellers who can produce them at the least cost (9). Oils that contain trans fats are less expensive, which allows food to be produced at a lower cost. Restaurants that produce food at the lowest cost will have the most business because the cost to the consumer is lower. So, the irony is that because the proposed ban in Chicago does not apply to all restaurants, the free market economy gives an advantage to smaller restaurants that can still serve trans fats. This means that the ban will not be substantially effective in reducing obesity because consumers are likely to eat trans fats at these less expensive, smaller restaurants.

Finally, Chicago’s proposed ban on trans fats would not eliminate obesity because it does not address the multiple causes of obesity in the American lifestyle. While the single-pronged approach could be effective for some health problems, it is not suitable for the problem of obesity. Epidemiologic studies, supported by the ‘web of causation’ model of epidemiology, have shown that many factors contribute to obesity. This model suggests that this single-causation view is not an effective way to view or combat a disease like obesity, which has so many contributing factors. The proposed ban focuses on trans fats as the sole cause of obesity in Chicago instead of concentrating on multiple causes.

First published in a textbook in 1960, the ‘web of causation’ model was suggested as a way to determine the etiology of a disease and to develop successful public health interventions. The model suggests the image of a spider’s web with the many strands and their intersections representing pathways, risk factors, and outcomes. Epidemiologists who use this model are required to look for multiple causes of a disease and to consider the interactions of the many causes. (10)

The model was proposed as an alternative to the germ-theory because chronic conditions were on the rise, and they cannot be explained by a single agent (10). In Chicago, this is precisely the problem with the proposed ban. Obesity is a chronic condition, and its cause cannot be described as trans fat, which is a single agent that play a limited and non-essential role in the pathway to obesity.

Countless research has been done to reinforce the multiple causes of obesity in America. There are behavioral causes, such as high calorie consumption and lack of physical activity. Societal causes also play a role. Examples of these are availability of calorie-dense foods, lack of access to physical activity, advertising, the free market, and restaurants using oils containing trans fats. More importantly, all of these causes are affected by risk factors that can increase a person’s chances of becoming obese. Risk factors include socioeconomic status, education, and family history.

While the ‘web of causation’ suggests that all of these causes and factors play a role in causing obesity, each one makes a different contribution. Some play a more direct role than others. Altering one may have a slight effect on the problem of the disease, but in order to eliminate obesity, many causes and their interactions must be addressed in a public health intervention. Chicago’s proposed ban on trans fats only addresses the use of trans fats by restaurants, which, it could be argued, does not play nearly as important a role in obesity causation as limited physical activity or high calorie consumption. And, the ban does not take the step to completely ban the use by all restaurants, so its intervention is exceedingly limited. If the City of Chicago wants to reduce obesity among its population, it needs to address more than one cause of obesity in a broad and effective intervention.

In conclusion, Chicago’s ban on trans fats in restaurants is too limited for a public health intervention, especially since it only applies to large, chain restaurants. Chicagoans will not have significantly reduced access to trans fats both because they are still available in some restaurants, in supermarkets, and in restaurants just outside of the Chicago City Council’s jurisdiction. Also, the free market economy suggests that consumers will purchase food at restaurants that have cheaper prices, which will be those restaurants not affected by the ban who can still offer food containing trans fats. Finally, the ban only addresses one of many causes of obesity. An intervention for obesity should use the ‘web of causation’ model to combat a disease because it takes into account the multiple causes, risk factors, and their interactions. For these reasons, Chicago’s proposed ban on trans fats will not be effective in significantly reducing obesity, and the City Council should explore other options to fight obesity in the area.

(1) Bocskay, K., Harper, D., Thomas S. (2005). Leading causes of death in Chicago. Health Index Series: Vol. XV No. IV. Chicago, Illinois: Chicago Department of Public Health Office of Epidemiology.
(2) Ascherio, A. (2006, May). Trans fatty acids and blood lipids. Atherosclerosis Supplements 7(2), 25-7.
(3) Katan, M. (2006, May). Regulation of trans fats: the gap, to Polder, and McDonald’s French fries. Atherosclerosis Supplements 7 (2), 63-6.
(4) Odegaard, A., &Pereira, M. (2006, August). Trans fatty acids, insulin resistance, and type 2 diabetes. Nutrition Reviews 64 (8), 364-72.
(5) Bracket, E. (Correspondent). (2006, August 16). Chicago City Council proposed anti-trans fats ordinance. The Online NewsHour with Jim Lehrer.
(6) Davey, M. (2006, July 18). Chicago weighs new prohibition: Bad-for-you fats. The New York Times.
(7) Chicago Sun-Times News Group Wire. (2006, July 18). Burke limits no-fat proposal to fast food giants.
(8) Chicago Transit Authority. (2005). Throughout city and suburbs: meeting the need for transit. Proposed 2005 Annual Budget Summary.
(9) Mankiw, N. (2004). Principles of microeconomics: 3rd edition. South-Western.
(10) Krieger, N. (1994). Epidemiology and the web of causation: has anyone seen the spider? Social Sciences and Medicine, 39, 887-903.


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