This past holiday season, University of Wisconsin-Madison nutritionist Sherry Tanumihardjo made brownies with butter, not margarine. Like a lot of us, she wanted to avoid artificial trans fats.
Tanumihardjo knows a thing or two about fats. She developed educational materials about fats for the Wisconsin Nutritional Education Program, which aims to help Wisconsin citizens make healthier dietary choices.
You don't have to be a nutrition expert to share Tanumihardjo's concern. You've probably noticed the "no trans fats" message in food ads and labeling. You may have heard that New York City's health board passed a ban on the use of trans fats in the city's restaurants.
So, what is the skinny on trans fats? What are they? Why is this long-time food industry staple on the blacklist now? What will New York City eateries - and the rest of us - use in their place? Are the alternatives really healthier?
Keep reading as Tanumihardjo and other UW-Madison experts answer some frequently asked questions about trans fats.
What Are Trans Fats?
Hydrogenated vegetable oil has long been the preferred oil for making processed foods because it has a long shelf life, a buttery consistency at room temperature and is cholesterol-free. Due to the way hydrogenated vegetable oil is manufactured, it contains artificial trans fats, a class of fat molecules with a distinct chemical structure.
"Trans fats commonly show up in cookies, cakes, stick margarine and microwave popcorn," says Tanumihardjo, associate professor of nutritional sciences in the university's College of Agricultural and Life Sciences. Trans fats are also typically found in the deep fryer vats that crank out the French fries and other greasy goodies that we all love so much.
Trans fats have been around for longer than you might imagine; Crisco, the first hydrogenated oil, appeared on grocery store shelves in 1911.
What Are Natural (vs. Artificial) Trans Fats?
It is important to distinguish artificial trans fats from natural trans fats, which are found in dairy products and meats. Although natural trans fats are molecularly similar to artificial trans fats, they are widely considered to be healthier than their artificial brethren, and will not be discussed here. Besides, studies indicate that natural trans fats make up only a minor fraction of the total trans fats consumed by Americans.
Why Are Artificial Trans Fats Bad?
There was a time, not so long ago, when hydrogenated vegetable oil was widely considered to be healthier than the major alternative fats, such as butter and lard.
"This was a vegetable product," says Tanumihardjo, referring to the common thinking then. "It didn't contain cholesterol like butter or lard."
However, it was later discovered that hydrogenated vegetable oil negatively affects human cholesterol nonetheless. Trans fats in hydrogenated vegetable oil cause an increase in blood levels of low-density lipoprotein, or LDL, which is commonly known as "bad cholesterol." LDL's job is to transport cholesterol to the tissues of the body, and it can wreak havoc on its way.
"As LDL travels through the blood [carrying cholesterol to the tissues], it can deposit some of the cholesterol in the arteries, leading to plaques and atheroschlerosis," explains James Ntambi, UW-Madison professor of biochemistry and nutritional sciences.
Ntambi notes that, on the other hand, HDL, or "good cholesterol," transports cholesterol to the liver, where it is destroyed and excreted from the body. The polyunsaturated fat known as Omega-3 fatty acid increases HDL levels, and is considered heart healthy. It is found in the oil of many types of fish.
More generally, all unsaturated fats - both polyunsaturated and monounsaturated - are considered healthful, in the sense that they do not increase risk for heart disease. Unsaturated fats are found in vegetable oils and nuts, in addition to fish.
What Are The Alternatives?
While Crisco has already developed a trans fat-free product and others are doing the same, "Nabisco and Kraft can't buy as much [trans fat-free oils] as they need at this point," says Barbara Ingham, associate professor of food science at UW-Madison.
To replace trans fats, many food producers are reaching for saturated fats, such as palm oil, coconut oil and cocoa butter. Unfortunately, saturated fats don't offer much of a health benefit over trans fats, if any. The USDA lumps trans fats and saturated fats together; both types raise LDL and are considered unhealthful.
So, when you reach for a bag of trans fat-free chips, don't be tricked into thinking that you're choosing a healthy alternative to regular chips. That may not be the case; you need to read the nutrition label.
More promising alternatives to trans fats are at various stages of development. Blended oils are already available, says Ingham, noting that Land O'Lakes sells a spread made from real butter and "healthy" vegetable oil. The spread is trans fat-free, and has lower cholesterol than straight butter.
On the technology front, chemists are trying to perfect ways to hydrogenate vegetable oils without producing trans fats. Also, some agribusinesses are engineering oil-producing plants to yield "desirable" oils-ones that can be used without undergoing the standard processing that causes trans fats to form.
"The trans fat ban in New York City will accelerate this process [of creating and producing better fats] within the industry," says Ingham. "This will be an opportunity for the food industry to respond positively to a health issue. As with the low carb diet craze, the food industry has shown that it can respond quickly if there is consumer demand for change."
Will Switching Oils Make French Fries A Healthy Food?
Trans fat-free French fries are not significantly healthier, says Tanumihardjo, because "even though restaurants in New York will be taking out the bad guy [trans fats], they are adding back saturated fats."
"Watching total fat consumption is important," she emphasizes. "You've got to consider the total diet and exercise."
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