What Are Trans Fats & Why Should We Avoid Them?
Trans fat, or trans-unsaturated fatty acids, trans fatty acids, are a type of unsaturated fat that occur in small amounts in nature, but became widely produced industrially from vegetable fats for use in margarine, snack food, packaged baked goods, and frying fast food starting in the 1950s. Trans fat, has been shown to consistently be associated, in an intake-dependent way, with increased risk of coronary artery disease, a leading cause of death in Western nations.
Trans fatty acids are made when manufacturers add hydrogen to vegetable oil — in a process described as partial hydrogenation. If the hydrogenation process were allowed to go to completion, there would be no trans fatty acids left, but the resulting material would be too solid for practical use. Usually the hydrogen atoms at a double bond in a natural fatty acid are positioned on the same side of the carbon chain. However, partial hydrogenation reconfigures most of the double bonds that do not become chemically saturated, so that the hydrogen atoms end up on different sides of the chain. This type of configuration is called trans (which means “across” in Latin).
Fats contain long hydrocarbon chains, which can either be unsaturated, i.e., have double bonds, or saturated, i.e., have no double bonds. In nature, unsaturated fatty acids generally have cis as opposed to trans configurations. In food production, liquid cis-unsaturated fats such as vegetable oils are hydrogenated to produce saturated fats, which have more desirable physical properties, e.g. they melt at a desirable temperature (30–40 °C). Partial hydrogenation of the unsaturated fat converts some of the cis double bonds into trans double bonds by an isomerization reaction with the catalyst used for the hydrogenation, which yields a trans fat.
Partial hydrogenation increases the shelf life and flavor stability of foods containing these fats. Partial hydrogenation also raises the melting point, producing a semi-solid material, which is much more desirable for use in baking than liquid oils. Partially hydrogenated vegetable oils are much less expensive than the fats originally favored by bakers, such as butter or lard. Because they are not derived from animals, there are fewer objections to their use.
Although trans fats are edible, consumption of trans fats has been shown to increase the risk of coronary artery disease in part by raising levels of the lipoprotein LDL (often referred to as “bad cholesterol”), lowering levels of the lipoprotein HDL (often referred to as “good cholesterol”), increasing triglycerides in the bloodstream and promoting systemic inflammation.
Trans fats also occur naturally. Vaccenyl and conjugated linoleoyl (CLA) containing trans fats occur naturally in meat and dairy products from ruminants. Butter, for example, contains about 3% trans fat. Two Canadian studies have shown that vaccenic acid, found in beef and dairy products, could actually be beneficial compared to hydrogenated vegetable shortening, or a mixture of pork lard and soy fat, by lowering total and LDL and triglyceride levels. A study by the US Department of Agriculture showed that vaccenic acid raises both HDL and LDL cholesterol, whereas industrial trans fats only raise LDL without any beneficial effect on HDL.
In light of recognized evidence and scientific agreement, nutritional authorities consider all trans fats equally harmful for health and recommend that consumption of trans fats be reduced to trace amounts. In 2003 the World Health Organization recommended that trans fats make up no more than 1% of a person’s diet. In 2013, the United States Food and Drug Administration (FDA) issued a preliminary determination that partially hydrogenated oils (which contain trans fats) are not “generally recognized as safe”, which was expected to lead to a ban on industrially produced trans fats in the American diet. On 16 June 2015, the FDA finalized its determination that trans fats are not generally recognized as safe, and set a three-year time limit for their removal from all processed foods.
Two sources: There are two types of trans fat, according to the U.S. Food and Drug Administration (FDA)
- Naturally formed trans fat: This type is produced in the gut of some grazing animals, so small quantities of trans fats can be found in meat, milk and milk products.
- Trans fat formed during food processing: Artificial trans fats are created when hydrogen is added to (unsaturated) liquid vegetable oils to make them more solid. Food manufacturers use partially hydrogenated oils (PHOs) to improve texture, shelf life and flavor. PHOs are the main source of this type of trans fat in the United States, according to the FDA.
PHOs were discovered in 1902 by scientist Wilhelm Normann. For many years, it was thought that eating shortening or margarine made from PHOs was preferable to butter because they didn’t contain saturated fat. It wasn’t until the 1980s that researchers started uncovering the health hazards that come from consuming PHOs. In 2015, the FDA determined that partially hydrogenated oils are no longer “generally recognized as safe” (GRAS) in human food and took steps to restrict its use. According to the new restrictions, companies must remove PHOs from their food products by June 2018. Removing trans fat could prevent up to 20,000 heart attacks, and 7,000 deaths from heart disease each year in the United States, the Centers for Disease Control and Prevention estimated.
Before the advent of partial hydrogenation, the only trans fat that humans consumed came from eating cows (or dairy products), lamb, and deer; in ruminants like these, bacteria living in the stomach make small amounts of trans fat. But due to the growth of partial hydrogenation, by the early 1990s, trans fat intake in the United States averaged 4 to 7 percent of calories from fat.
In 1981, a group of Welsh researchers speculated that trans fat might be linked with heart disease. A 1993 Harvard study strongly supported the hypothesis that intake of partially hydrogenated vegetable oils contributed to the risk of having a heart attack. In that study, the researchers estimated that replacing just 2 percent of energy from trans fat with healthy unsaturated fat would decrease the risk of coronary heart disease by about one-third. An influential symposium on trans fat later in the 1990s drew public attention to the issue.
The FDA recommends eating as little trans fats as possible. Finding out if a product has trans fats can be tricky, though. A food can list “0 grams of trans fats” on the label but still contain less than 0.5 grams of trans fat per serving in the United States, according to the Mayo Clinic. The FDA also noted that trans fats have no percent daily value (%DV) on nutrition labels, so the grams (g) labeling is all that is posted on the label. A better indicator of trans fat content may come from reading the ingredients list. If a food contains partially hydrogenated oils, it contains trans fats.
What Are the Health Consequences of Consuming Trans Fat?
- Gram-for-gram, trans fat is the most harmful fat of all, causing 50,000 fatal heart attacks annually. In 2016, the Food and Drug Administration finalized its determination that artificial trans fat is no longer generally recognized as safe for use in food.
- Consuming trans fat increases low-density lipoprotein (LDL, or “bad”) cholesterol. This effect contributes to increased coronary heart disease and death.
- Trans fat may also have other adverse health effects like decreasing high-density lipoprotein (HDL, or “good”) cholesterol.
- Known to trigger systemic inflammation, trans fat can be found in fast foods and other fried products, processed snack foods, frozen breakfast products, cookies, donuts, crackers and most stick margarines. Avoid foods with partially hydrogenated oils in the ingredient labels.
- Further reducing trans fat consumption by avoiding artificial trans fat could prevent 10,000–20,000 heart attacks and 3,000–7,000 coronary heart disease deaths each year in the U.S.
Artificial trans fat can be found in many of the same foods as saturated fat, including:
- Baked goods (cookies, cakes, pies, and crackers)
- Ready-to-use frostings
- Snack food (such as potato chips and microwave popcorn)
- Fried food typically found in fast food restaurants (such as French fries, fried chicken, and doughnuts)
- Refrigerated dough products (such as biscuits, cinnamon rolls, and frozen pizza)
- Vegetable shortening
- Stick margarine
- Coffee creamer
The amount of trans fat can vary within food categories:
- Margarine and spreads 0.0-3.0 g
- Cookies 0.0-3.5 g
- Frozen pies 0.0-4.5 g
- Frozen pizza 0.0-5.0 g
- Savory Snacks 0.0-7.0 g
What Can Be Done to Reduce Artificial Trans Fat Intake?
- Read the Nutrition Facts label and ingredient list to compare foods. Choose products with 0 grams trans fat. Check the Ingredient List to see if there is any partially hydrogenated oil in the product. Because products containing less than 0.5 grams of trans fat per serving can be labeled as having 0 grams trans fat, checking the Ingredient List is important to avoid all artificial trans fat.
- When choosing foods low in trans fat, make sure they are also low in saturated fat and cholesterol: look for foods with 5% of the Daily Value or less. Foods with 20% or more of the Daily Value of these two components are high.
- Use monounsaturated fat (canola and olive oil) and polyunsaturated fat (soybean, corn, and sunflower oil) in recipes that call for fat.
- A good way to avoid trans fat is to eat a balanced diet rich in fruits, vegetables, whole grains, lean sources of protein, and low-fat or fat-free dairy products.
- Ask your grocer to stock products free of “partially hydrogenated oil” and “shortening”.
- Talk with your favorite restaurant establishment about current use of partially hydrogenated oils or changing to a menu that is 100% free of “partially hydrogenated oil” and “shortening”.
- Choose restaurants that do not use partially hydrogenated oil to prepare food.
Margarine Sticks & Spreads
Not so long ago, margarine was marketed as a healthier alternative to butter because it’s made from vegetable oil instead of dairy or animal products. But for the margarine to maintain its solid form, many brands (especially stick varieties) depend on hydrogenated oils that are high in trans fat and/or saturated fat. Steer clear of Blue Bonnet Regular Sticks (1.5 grams per serving), and instead opt for whipped, reduced-fat, or fat-free soft spreads.
Developed in the 1800s in France when butter was scarce and expensive, margarine has had its ups and downs, including several U.S. bans and taxes driven by the dairy industry. It’s been called a healthier, plant-based alternative to butter, but it also faced a backlash for being artificial and having trans fats, which help keep oil-based ingredients solid at room temperature. Margarine is any vegetable-oil-based, butter-flavored spread that contains 80% oil; anything with a lower oil and fat content is called a “soft margarine spread.”
To stay solid at room temperature, vegetable oils are hydrogenated, which creates trans fatty acids that can raise LDL, or bad cholesterol. Most solid sticks of margarine contain trans fats and/or saturated fat. These include Country Crock Spreadable Sticks (80 calories, 1.5 grams saturated fat, 2 grams trans fats), Blue Bonnet Sticks (70 calories, 1.5 grams saturated fat, 1.5 grams trans fat), Land O’Lakes Margarine Sticks (100 calories, 2 grams saturated fat, 2.5 grams trans fats), and Fleischmann’s Original Stick Margarine (80 calories, 2 grams saturated fat, 1.5 grams trans fat).
The American Heart Association suggests buying soft, trans-fat-free spreads instead of regular butter or stick margarine. Choose a blend with the least amount of saturated fat and zero trans fats. Check the ingredients: If it says partially hydrogenated oils, it still has some trans fat (less than 0.5 gram per serving), even if the label says trans fat free.
A gram or two of trans fats may not seem like a lot, but even small amounts are bad for the heart. Baker recommends keeping trans-fat intake as low as possible. There are trans-fat-free options if you need hard butter or margarine for baking. Promise Sticks contain 80 calories per serving, and 9 grams of fat (2.5 grams saturated). I Can’t Believe It’s Not Butter Sticks and Earth Balance Vegan Buttery Spreads contain no trans fats, but they still have 3.5 grams and 4.5 grams of saturated fat, respectively, and the same amount of total fat and calories as butter.
Soft spreads packaged in a tub are generally much healthier for your heart, because they contain less saturated fat and many are trans fat free. Some examples include Fleischmann’s Original Whipped Tub with 60 calories and 7 grams of fat (1 gram saturated) per serving, Smart Balance Original Buttery Spread with 80 calories and 9 grams of fat (2.5 grams saturated), and Blue Bonnet Soft Spread with 60 calories and 6 grams of fat (1 gram saturated).
Is Butter Better?
Regular butter is made with one ingredient: cow’s milk or cream, churned or shaken until it reaches a semisolid state. By definition, it contains at least 80% milk fat by weight, and it takes about 11 quarts of milk to make 1 pound of butter. Traditionally, butter comes in salted and unsalted varieties, and it can be found in solid stick form or whipped and packaged in plastic tubs. You may also find cultured butter, a rich butter made from cultured cream popular in Europe, at your grocery store or specialty foods store.
Most “original” butter sticks contain 100 calories per tablespoon, a typical serving size. One serving has 11 grams of fat, and 7 grams of it is artery-clogging saturated fat—about one-third of your recommended daily value! It also contains 30 milligrams of dietary cholesterol (10% of your daily value). Some have even more fat; Ireland’s Kerrygold Unsalted Pure Irish Butter, for example, contains 12 grams of fat, 8 grams of it saturated.
Better: Whipped butter
The process of whipping adds air to the butter, making it lighter and less dense. If you can stick with the same tablespoon-size portion, you’ll save up to half the calories and saturated fat by choosing whipped butter in a tub. Land O’Lakes Whipped Butter, for example, contains 50 calories and 6 grams of fat (3.5 grams saturated), and only 15 milligrams of cholesterol per serving.
Even Better: Vegetable-oil blends
A butter blend with added olive or canola oil won’t cut calories or fat much or at all—most have 100 calories and 11 fat grams per serving—but it will lower saturated fat and cholesterol. What’s more, these are typically softer and easier to spread right out of the refrigerator. To lower calories, select a “whipped” or a “light” blend. We like Shedd’s Spread Country Crock Spreadable Butter with Canola Oil (80 calories and 9 grams of fat, 3.5 saturated), and Land O’Lakes Light Butter with Canola Oil (50 calories and 5 grams of fat, 2 saturated).
Beware of What’s Replacing Trans Fats & Partially Hydrogenated Oils
(Bloomberg.com by Deena Shanker)
Research showing the dangers of trans fat, which raises the risk of heart disease and stroke, solidified with a major study published in 1990 and got stronger with each successive round of research, forcing food makers to start looking for alternatives. From 2006 to 2008, according to one estimate, the amount of PHOs in food in North America was cut in half. By 2015, the Grocery Manufacturers Association said trans fat had been reduced by 85 percent. That year, the U.S. Food and Drug Administration announced that food makers had three years to completely remove the oils from their products.
PHOs come in many forms and serve a variety of hidden functions. They could be in the deep fryer at a national fast-food chain or in your favorite packaged baked goods—you know, the ones that tastes as fresh today as when they were purchased three years ago. They’ve shown up in creamers, cereal bars and microwave popcorn. Replacing them requires a mix of liquid oils and solid fats, along with collaboration among oil-producers, fast-food industry and packaged food producers.
Consumers likely won’t be able to tell the difference when they sample the new generation of PHO-free products. In fact, many have already been eating them for years. Nutritionally, all are an improvement over standard partially hydrogenated soybean oil. Producers tout their high content of “good fats,” (aka monounsaturated and polyunsaturated fats) and low levels of “bad fats” (trans and saturated fats). Omega-9 fatty acids, or oleic acid, makes the oil both more stable and healthful. (The high oleic acid content of olive oil is one reason it is considered the gold standard of healthy oils.) Yet these oils fall short in at least one respect: Because all the new oils are liquid, baking with them requires the addition of other solid fats. In these cases, palm oil, an ingredient associated with negative environmental impacts, is often the solid fat of choice.
Non-GMO Omega-9 canola oil, from Dow Chemical Co.’s Dow AgroSciences LLC, has even lower levels of saturated fats than olive oil and about the same level of omega-9s. “This oil has the whole package,” said Dave Dzisiak, the global business leader of oils and grains at the company. The oil also has a cleaner, light taste, he said. It’s currently being used by major national and regional foodservice chains, as well as by snack makers, according to the company.
DuPont Co.’s DuPont Pioneer subsidiary makes similar claims about its trans-fat free oil, Plenish. Through genetic modification, the company lowered the amount of saturated fat in standard soybean oil by 20 percent and raised the omega-9 fatty acids to rival that of olive oil. Plenish is also currently being used in packaged goods, according to DuPont. It believes its soy oil holds a competitive advantage over canola because soy is so entrenched in the American diet. “There’s a pretty strong belief that the U.S. consumer in particular has developed a preference for soy,” said Russ Sanders, director of food at DuPont. “The flavor of the food comes through more than the flavor of the oil.”
Monsanto Co. is banking on the same preference as it prepares to launch its own soybean oil, Vistive Gold. Like its competitors, Vistive Gold has a high omega-9 count, low saturated fat content and better stability than standard soybean oil. It is also a product of genetic engineering. The company declined to name any specific customers, but a spokesperson said it has been working closely with the food industry to develop an oil producers will want to use.
At the moment, high-oleic canola oils are more popular, largely because they have been around in commercial quantities much longer than the new soybean oils, said Robert Collete, president of the Institute of Shortening and Edible Oils. (High-oleic sunflower oils have also been available for some time in lower quantities.) But the soybean industry is fighting back with Qualisoy, an organization that promotes high-oleic soybean oil, including Plenish and Vistive Gold.
- S. Department of Agriculture and U.S. Department of Health and Human
- Dietary Guidelines for Americans, 2010. 7th Edition, Washington, DC: U.S. Government Printing Office, December 2010.
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press, Washington, DC, 2005.
- Doell D, Folmer D, Lee H, Honigfort M, Carberry S. 2012. Updated estimate of trans fat intake in the U.S. population. Food Additives & Contaminants: Part A: Chemistry, Analysis, Control, Exposure & Risk Assessment.
- Dietz WH, Scanlon, KS. 2012. Eliminating the Use of Partially Hydrogenated Oil in Food Production and Preparation. JAMA. 2012;308(2):143-144.