Boston -- In December, New York City passed a law to phase out the use of trans fat in restaurants. Other cities, including Boston and Chicago, might follow suit. According to Alice H. Lichtenstein, DSc, Gershoff professor of nutrition science and policy at the Friedman School of Nutrition Science and Policy at Tufts University, the ban is a step in the right direction, but restaurateurs need to replace partially hydrogenated fat with unsaturated fat. If they choose saturated fat it would diminish the health benefits of this new initiative. Another new regulation that requires some restaurants to provide calorie information as prominently as price might be even more important, notes Lichtenstein.
"There is no biological need for trans fat and intake is associated with adverse health outcomes. However, the media attention on the trans fat announcement to the exclusion of the calorie labeling is unfortunate. Two-thirds of Americans are overweight or obese. The New York City Department of Health and Mental Hygiene has proposed that the calorie content of food items be displayed as prominently as the price, at the point of purchase," says Lichtenstein, also director of the Cardiovascular Nutrition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts.
"That means," Lichtenstein continues, "that if you are wavering between placing an order for a small versus a medium order of French fries, both the price and the number of calories per serving will be displayed. People will become more aware of the caloric cost of the foods they order, and the next step on a public health level would be to educate the consumer on the amount of calories their body needs per day. This way, they will be able to put the numbers they see on the board or menu into perspective. Because the amount of food and beverages we eat that is prepared outside the home is so large, even if this regulation just covers a fraction of food service establishments, it can have a tremendous impact on caloric intake."
"Trans fat," says Lichtenstein, "is a double whammy, because like saturated fat, it raises levels of LDL or 'bad cholesterol,' but it also lowers levels of HDL or 'good' cholesterol." Most of the trans fats we eat are formed during the partial hydrogenation of oils used in fried foods and commercial baked goods. Partially hydrogenated oils provide processed foods with longer shelf lives and therefore greater economic profitability.
"But, trans fat is just one part of the diet. In general, people are still eating far more saturated fat than trans fat, and both need to be reduced in order to maintain optimal cholesterol levels and promote heart health," says Lichtenstein. "And the big giant – total calories – is always looming in the background."
In one study to assess the effects of consuming different types of oils on cholesterol levels, led by Lichtenstein and published earlier this year, fifteen adult volunteers with moderately high LDL cholesterol were fed each of four diets with a different source of primary fat, including partially hydrogenated soybean oil (trans fat), palm oil (50 percent saturated fat), non-hydrogenated soybean oil (only 16 percent saturated fat), and canola oil (only 7 percent saturated fat).
The results, published in the American Journal of Clinical Nutrition (AJCN), reported that after a trial of 35 days on each diet, participants consuming the partially hydrogenated soybean oil and palm oil diets had levels of LDL cholesterol that were 12 and 14 percent higher, respectively, than when consuming the non-hydrogenated soybean oil diet. An even greater difference was observed when the partially hydrogenated soybean oil and palm oil diets were compared to the canola oil diet. While participants were on the partially hydrogenated soybean oil and palm oil diets their LDL levels were 16 and 18 percent higher, respectively, than when on the canola oil diet.
"On the basis of this and other work, it's clear that phasing out partially hydrogenated oils (trans fats) will improve diet in some ways, "says Lichtenstein, corresponding author on the AJCN study. "However, just decreasing trans fat intake without changing other dietary habits, such as minimizing saturated fat intake and controlling total calorie intake, will result in some real disappointments with respect to both heart health and obesity."
Lichtenstein recommends that other cities monitor the successes and challenges of the trans fat ban in New York City before implementing their own regulations, and also advises that the focus on the new regulations shift to the mandate to display calorie labeling in food service establishments, and educating people about their total daily caloric requirements.
Vega-Lopez S, Ausman LM, Jalbert SM, Erkkila AT, Lichtenstein AH. "Palm and partially hydrogenated soybean oils adversely alter lipoprotein profiles compared with soybean and canola oils in moderately hyperlipidemic subjects." American Journal of Clinical Nutrition. 2006 (July);84(1):54-62.
If you are interested in learning more about this topic, or speaking with a faculty member at the Friedman School of Nutrition Science and Policy at Tufts University, or another Tufts health sciences researcher, please contact Siobhan Gallagher at 617-636-6586.
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight centers, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy. For two decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations. Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies.
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