Trans Fat: How to avoid the silent killer in your food

Trans fat intake is responsible for more than 278,000 deaths each year globally, according to the World Health Organization. Transfat kills, period! High intake of trans fats increases the risk of death from any cause by 34% [1]. While healthy fats are essential to a balanced diet, trans fats seriously threaten your health. Often hidden in processed foods, these silent killers can contribute to heart disease, stroke, and other chronic illnesses. Let's uncover the truth about trans fats and learn to avoid this killer ingredient altogether in your diet.

What are transfats?

Trans fats, also known as trans-fatty acids, are a type of unsaturated fat that can harm your health. While small amounts of trans fats occur naturally in some foods, the primary concern lies with industrially produced trans fats found in processed foods. The industrially-produced trans fats are created through hydrogenation, which adds hydrogen to liquid vegetable oil to make it more solid. This process alters the oil's chemical structure, creating trans fats, commonly known as partially hydrogenated oil (PHO). These artificial trans fats can raise harmful cholesterol levels, lower good cholesterol, and increase your risk of heart disease, stroke, and other health problems.

Sources of transfats

In the human diet, trans fat can come from three primary sources:

Industrial Trans Fats: Also called artificial trans fats, these trans fatty acids are created through hydrogenation, where hydrogen is added to liquid vegetable oils to make them more solid. This process produces trans fats that are not naturally found in foods. The industry uses hydrogenation because the process increases the shelf life, flavor, and texture of foods. This saves the food industry money and increases sales by making the food more appealing to consumers. The most significant example of artificial trans fat is partially hydrogenated oil (PHO), where the concentration of trans fat is close to 25%-45% [1].

Natural Trans Fats: A process known as biohydrogenation occurs in the rumen of ruminant animals (like cows and sheep) and can produce small amounts of trans fats in their meat and dairy products. While there is no definite conclusion on whether natural trans fats have the same adverse effects as industrial trans fats, [2] the high amount of saturated fat in animal-derived food is connected with various diseases.

Heat Processing: High-temperature cooking methods, such as frying, can create trans fat, even if you use an oil that doesn't have hydrogen added to it. For example, frying oil at high temperatures does produce a small amount of trans fat. Although this increase is small (2-3%) compared to the levels found in PHOs, eating fried food consistently can lead to the same adverse health effects [2]. For example, chemicals called HCAs and PAHs can form when you cook meat at high temperatures (like grilling or pan-frying). Lab tests have shown that these chemicals can damage DNA, which might increase the risk of cancer [3]. Similarly, the Indian spice tempering technique or frying/stir-frying food with oil at smoking temperatures can potentially add trans fats to foods.

Why food companies use trans fats and current status in the US

Trans fats have a surprisingly long history, dating back to the late 19th century. Partially hydrogenated oils (PHOs) became the most used form of transfats in more than 100 years since its inception in the early 1900s.

PHOs were attractive to the food industry for two main reasons. First, they significantly extended the shelf life of products. Second, they provided a texture and taste that consumers enjoyed in many foods, such as baked goods and fried items.

From the 1950s to the 1980s, PHOs were wrongly believed to be healthier than saturated fats. This misconception led to a surge in their use in place of animal-based fats.

Here is a timeline of trans fat inception to the fall of trans fat use in food.

1890s: French chemist Paul Sabatier lays the groundwork by discovering how to use metal catalysts to add hydrogen to organic compounds, a process called hydrogenation [4].  
1903: German chemist Wilhelm Normann successfully applies hydrogenation to liquid oils, creating a semi-solid fat called trans fat. This was a game-changer for the food industry [4].  
Early 1900s: Trans fats, in the form of partially hydrogenated oils (PHOs), become widely used in margarine, shortening, and processed foods. Food manufacturers and restaurants love PHOs' affordability, long shelf life, and ability to improve the texture of baked goods.
1950s-1980s: Concerns about saturated fat and cholesterol led to the increased use of trans fats as a seemingly healthier alternative.
1990s: Research begins to show a strong link between trans fats and heart disease, revealing that they raise "bad" LDL cholesterol and lower "good" HDL cholesterol [2].  
2000s: Public awareness of the dangers of trans fats grows, leading to labeling requirements and restrictions on their use in food.  
2015: The FDA determines that PHOs are no longer "generally recognized as safe" and sets a deadline for their removal from food.
2018: The FDA broadly bans PHOs, effectively eliminating artificial trans fats from most processed foods in the United States [5].

Trans fat's lingering presence post-ban

The WHO recommends limiting trans fat to less than 1% of your daily calories, which is about 2 grams for a 2,000-calorie diet. While trans fat is banned in many countries, a small amount is still permissible. Moreover, many countries, including Australia, Azerbaijan, Bhutan, Ecuador, Egypt, Iran (Islamic Republic of), Nepal, Pakistan, and the Republic of Korea, haven't instituted the ban since January 2023.

The other big concern is that many countries, even if they have instituted the trans fat ban, don't have stringent policy adherence systems to enforce the ban on food and food service manufacturers. The best way to avoid it is to detect it in food yourself.

What foods contain transfats?

While artificial trans fats have been largely eliminated from the U.S. food supply, they can still lurk in some unexpected places. These sneaky sources of trans fat often hide in processed foods, baked goods, and fried items, posing a hidden risk to your health. If you live in a country that has not enforced the trans fat ban, read food labels and/or inquire about manufacturers. Understanding where trans fats commonly hide can help you make informed choices and protect yourself from their harmful effects. The artificial PHOs can be primarily found in the following food categories:

Food Category	Common foods
Packaged baked goods	Cookies, crackers, frosting, sweet and savory pies, cakes, etc.
Frozen packaged items	Pizza crust, cookie dough, biscuits, cinnamon rolls, breakfast sandwiches, frozen dinners, etc.
Baked food items	Pie crust, cakes, muffins, etc.
Beverages	Non-dairy creamers both powdered and liquid,
Snacks	Popcorn, Indian Bhajia (fried snack), chips, etc.
Spreads	Margarine

The man-made trans fats are primarily found in the fried foods such as :

• French fries
• Chicken wings
• Onion rings
• Fried food at home
• Any recipe that heats oils at high temperatures, such as spice tempering,

Health risks associated with transfats

It's worth repeating that trans fat KILLS! Trans fat intake, mainly industrially produced PHOs, is linked with various diseases, some of which are life-threatening [2]. It increases the mortality rate by 34% due to any cause [1].

According to the U.S. Food and Drug Administration, removing trans fat from foods is estimated to have prevented thousands of heart attacks and deaths annually [2]. Some of the diseases linked with trans fat intake are as follows:

Increased Risk of Heart Disease: Trans fats raise levels of "bad" cholesterol (LDL) and lower levels of "good" cholesterol (HDL). This imbalance increases the risk of heart disease, heart attack, and stroke. Trans fat intake increases the coronary heart disease death risk by 28% and coronary heart disease by 21% [1]. Weight gain: Some scientific studies have found a direct link between trans fat intake and weight gain. According to some studies, subjects whose artificial trans fats consumption exceeded the recommended 1% of total energy intake exhibited a 5-fold increase of central adiposity or gaining fat on the midsection [2].
Inflammation: Trans fats can trigger chronic inflammation, contributing to various health problems, including heart disease, cancer, and Alzheimer's disease.

It's important to note that even small amounts of trans fats can significantly impact your health. Therefore, it's crucial to remove trans fats altogether from your diet.

How to avoid trans fat in your diet

In 2003, The World Health Organization (WHO) recommended that all trans fats be limited to less than 1% of overall energy (food) intake. Whether PHOs are banned in your country or not, you can restrict trans fat by taking the following steps.

1. Prepare most meals at home. This is the best way to ensure the purity of ingredients in your food.
2. Use caution when cooking with high heat, especially when using oils. Avoid overheating the oil to the point where it smokes.
3. Read food labels to check for trans fat. Often, food manufacturers are not required to list trans fat on food labels if it's included in small amounts. In the example of a packaged cake icing below, even though the trans fat amount is listed as ZERO, it still contains trans fat. The FDA allows manufacturers to write the trans fat amount as zero if the product contains less than 0.5 grams of trans fat per serving [7]. But remember, trans fat is harmful even in small amounts.

Trans-fat ban: manufacturers adapted to palm oil

Food manufacturers often look for solutions that boost profits. Therefore, they prioritize food recipes that enhance flavor, extend shelf life, and utilize cost-effective ingredients. While many countries have removed (or are in the process of) trans fats, another ingredient, palm oil, has replaced them. While palm oil is not shown to reduce the good type of cholesterol HDL, it is high in saturated fat, which is linked to heart diseases and other metabolic conditions [8].

Here is an example of a food label for French-fried onions from a top US grocery store brand, Trader Joe's (Nutrition label below). In another example, an Indian healthy snack brand shows palm oil in the ingredient list.

In a nutshell

Removing trans fat from your diet protects your heart and overall well-being. You can significantly reduce your risk of trans fat intake by avoiding processed foods, checking labels for partially hydrogenated oils, and choosing healthier cooking methods.