Goodbye to Trans Fats
The Food Journal
June 25, 2015
by guest columnist Dr. Ruth S. MacDonald, Professor and Chair, Food Science and Human Nutrition, Assistant Dean of Graduate Programs, College of Agriculture and Life Sciences, Iowa State University
On June 16, the FDA announced that partially hydrogenated oils (PHOs) will no longer be considered "generally recognized as safe" (GRAS) for use in human foods. With this change, PHOs will have to be removed from foods over the next three years. PHOs are the primary source of artificial trans fats. This change in policy is a response to scientific evidence that trans fats contribute to the risk for cardiovascular disease and other chronic illness including dementia. Since 2006, food manufacturers have been required to display the amount of trans fats in their food on the nutrition facts panel, which led many to reduce or eliminate these from their products. The FDA estimates that between 2003 and 2012 consumer consumption of trans fats was reduced by 78 percent.
Hydrogenation is a process that has been used in the food industry since the late 1960s to convert liquid vegetable oils into solid fats. By bubbling hydrogen gas through the oils in the presence of a catalyst, hydrogen ions are taken up by the double bonds within the fatty acid structure. This makes the fats ‘hydrogenated’ and changes their melting point. PHOs include margarines and shortenings, which are used in a wide range of food products including fried foods, pastries, cake mixes and frozen dinners. PHOs increase the shelf life of foods by reducing the potential for oxidation that causes rancidity, and they also provide structure and texture to the foods.
In the early years of understanding heart disease risk, health care providers believed that saturated fats, such as those found in butter and meats, increased cardiovascular disease risk. Therefore, it was widely recommended that people switch from butter to margarines to avoid saturated fats, and food manufacturers used more PHOs in their products. It was not recognized until more recently that the presence of trans fats in these products could be harmful.
Most naturally occurring fatty acids, and those found in the body, are in the cis-orientation. This has to do with the rotation of the carbon chain around the double bond. Trans fatty acids are inverted forms of these fats, and in the process of producing PHOs some of the fatty acids end up in the trans-orientation. This unnatural orientation may be one of the reasons trans fats may cause harm to the cardiovascular system. Evidence suggests that when trans fats are present in the circulation they increase the amount of the bad lipoproteins, the LDLs, and also increase inflammation. People who consume high amounts of trans fats, primarily from consumption of foods containing PHOs, have been found to have higher rates of cardiovascular disease. However, there is not enough data to define what amounts of trans fats actually increase risk. A meta-analysis that compiled data from many research studies found that a two percent increase in energy intake from trans fats was linked to a 23 percent increase in risk of heart disease. Based on these estimates, eliminating all trans fats from the food supply would reduce overall heart disease risk significantly.
It is important to note that some foods naturally contain trans fats. Ruminant animals, including cows and sheep, have bacteria in their stomachs that generate trans fats. Hence, cheese, milk, butter and beef contain these ruminant trans fats. The types of fatty acids found in dairy foods and beef are structurally different from those generated by hydrogenation of vegetable oils. And research suggests that unlike artificially generated trans fats, these ruminant trans fats are not linked to negative health effects and may actually be protective of heart disease.
Food manufacturers have three years to meet the FDA requirement to remove all PHOs from their products. Because of the increasing awareness of the harm of trans fats and the required labeling of these fats, many foods have already been reformulated. But finding a suitable replacement for PHOs in some foods will be difficult. Adding more saturated fats to foods would not be desirable as these are also harmful to heart health. The texture and flavors of some foods will likely be changed as manufacturers work to find alternative ingredients to the PHOs. Fried foods, donuts, pastries, crackers and baked goods will be the most challenging products to reformulate as PHOs give them the flaky and light texture we have come to enjoy. But there are many food scientists who are well capable of finding solutions to this challenge, and it is certain that we will continue to enjoy great tasting and healthy foods.
Click here for more information on the trans fat ban.