Trans fat is a fat found in foods. Trans fat is made when a liquid vegetable oil is changed into a solid fat. Trans fat is often added to processed foods because it can improve taste and texture and helps the food stay fresh longer.
Why is trans fat bad for your health?
- Trans fat increases your risk of heart disease. This is because:
- Trans fat raises your LDL (bad) cholesterol AND
- Trans fat lowers your HDL (good) cholesterol
Fat is an important part of a healthy diet. It provides essential fatty acids and energy, and helps the human body absorb vitamins A, D and E. Fatty acids are sources of fuel because, when metabolized, they yield large quantities of ATP (adenosine triphosphate). Many cell types can use either glucose or fatty acids for this purpose. In particular, heart and skeletal muscle prefer fatty acids. Despite long-standing assertions to the contrary, fatty acids can be used as a source of fuel for brain cells.
Fatty acids that are required by the human body but cannot be made in sufficient quantity from other substrates, and therefore must be obtained from food, are called essential fatty acids.
There are two major types of fatty acids:
- Saturated fatty acids are long-chain carboxylic acids that have no carbon–carbon double bonds.
- Unsaturated fatty acids have some double bonds between carbon atoms in the chain.
What are TRANS FATS?
Trans fats are a type of unsaturated fats that are uncommon in nature but became commonly produced industrially from vegetable fats for use in margarine, snack food, packaged baked goods and frying fast food starting in the 1950s.
There are two main types of trans fats found in foods:
- naturally-occurring trans fats – produced in the gut of some animals and foods made from these animals may contain small quantities of these fats.
- artificial trans fats – created in an industrial process that adds hydrogen to liquid vegetable oils to make them more solid.
Meat, milk, and butter naturally contain small amounts of trans fat. The trans fat found naturally in foods is different than manufactured trans fat and does not increase your risk of heart disease.
The primary dietary source for trans fats in processed food is “partially hydrogenated oils.” Look for them on the ingredient list on food packages.
Scientific evidence has shown that dietary trans fats can increase your risk of developing coronary heart disease, the worldwide leading cause of death. To combat this, you can choose food for yourself and your children that contains little to no trans fat.
What “TRANS” actually means?
A little bit of chemistry
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.
Cis/trans isomerism (geometric isomerism, configurational isomerism) is a term used in organic chemistry to refer to the relative orientation of functional groups within a molecule. The terms “cis” and “trans” are from Latin, in which cis means “on this side” and trans means “on the other side” or “across”.
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.
Although trans fats are edible, consumption of trans fats has shown to increase the risk of coronary heart disease in part by raising levels of the lipoprotein LDL (so-called “bad cholesterol”), lowering levels of the lipoprotein HDL (“good cholesterol”), increasing triglycerides in the bloodstream and promoting systemic inflammation.
Most artificial trans fats are chemically different from natural trans fats.
History of Trans Fat
Historically, most trans fats have been found in such things as crackers, cookies, margarine (especially hard margarine), donuts, cakes, pastries, muffins, croissants, snack food and fried and breaded foods. Both the introduction of mandatory nutrition labelling on pre-packaged foods, and the two year recently completed Canadian Trans Fat Monitoring program have led to a reduction in the trans fat content of many, but not all foods.
But how it’s all started?
Nobel laureate Paul Sabatier worked in the late 1890s to develop the chemistry of hydrogenation, which enabled the margarine, oil hydrogenation, and synthetic methanol industries. The German chemist Wilhelm Normann showed in 1901 that liquid oils could be hydrogenated, and patented the process in 1902. During the years 1905–1910, Normann built a fat-hardening facility. At the same time, the invention was extended to a large-scale plant in Warrington, England. It took only two years until the hardened fat could be successfully produced in the plant in Warrington, commencing production in the autumn of 1909. The initial year’s production totalled nearly 3,000 tonnes.
In 1909, Procter & Gamble acquired the US rights to the Normann patent; in 1911, they began marketing the first hydrogenated shortening, Crisco (composed largely of partially hydrogenated cottonseed oil). Further success came from the marketing technique of giving away free cookbooks in which every recipe called for Crisco.
Normann’s hydrogenation process made it possible to stabilize affordable whale oil or fish oil for human consumption, a practice kept secret to avoid consumer distaste.
Prior to 1910, dietary fats consisted primarily of butterfat, beef tallow, and lard. During Napoleon’s reign in France in the early 19th century, a type of margarine was invented to feed the troops using tallow and buttermilk; it did not gain acceptance in the U.S. In the early 20th century, soybeans began to be imported into the U.S. as a source of protein; soybean oil was a by-product. What to do with that oil became an issue. At the same time, there was not enough butterfat available for consumers. The method of hydrogenating fat and turning a liquid fat into a solid one had been discovered, and now the ingredients (soybeans) and the “need” (shortage of butter) were there. Later, the means for storage, the refrigerator, was a factor in trans fat development. The fat industry found that hydrogenated fats provided some special features to margarines, which allowed margarine, unlike butter, to be taken out of the refrigerator and immediately spread on bread. By some minor changes to the chemical composition of hydrogenated fat, such hydrogenated fat was found to provide superior baking properties compared to lard. Margarine made from hydrogenated soybean oil began to replace butterfat. Hydrogenated fat such as Crisco and Spry, sold in England, began to replace butter and lard in the baking of bread, pies, cookies, and cakes in 1920.
In the 1940s, Catherine Kousmine researched the effects of trans fats on cancer.
Production of hydrogenated fats increased steadily until the 1960s, as processed vegetable fats replaced animal fats in the US and other western countries. At first, the argument was a financial one due to lower costs; advocates also said that the unsaturated trans fats of margarine were healthier than the saturated fats of butter.
As early as 1956 there were suggestions in the scientific literature that trans fats could be a cause of the large increase in coronary artery disease but after three decades the concerns were still largely unaddressed. In fact, by the 1980s, fats of animal origin had become one of the greatest concerns of dieticians. Activists, such as Phil Sokolof, who took out full page ads in major newspapers, attacked the use of beef tallow in McDonald’s French fries and urged fast-food companies to switch to vegetable oils. The result was an almost overnight switch by most fast-food outlets to switch to trans fats.
In 1994, it was estimated that trans fats caused 20,000 deaths annually in the US from heart disease.
Mandatory food labeling for trans fats was introduced in several countries. Campaigns were launched by activists to bring attention to the issue and change the practices of food manufacturers. In January 2007, faced with the prospect of an outright ban on the sale of their product, Crisco was reformulated to meet the United States Food and Drug Administration definition of “zero grams trans fats per serving” (that is less than one gram per tablespoon, or up to 7% by weight; or less than 0.5 grams per serving size) by boosting the saturation and then diluting the resulting solid fat with unsaturated vegetable oils.
Health Risks of Trans Fat
Hydrogenated vegetable oils have been an increasingly significant part of the human diet for about 100 years and some deleterious effects of trans fat consumption are scientifically proved.
The exact biochemical methods by which trans fats produce specific health problems are a topic of continuing research. One theory is that the human lipase enzyme works only on the cis configuration and cannot metabolize a trans fat. It leads to changes in the phospholipid fatty acid composition in the aorta, the main artery of the heart, thereby increasing risk of coronary heart disease.
High intake of trans fatty acids can lead to many health problems throughout one’s life. Trans fat is abundant in fast food restaurants. It is consumed in greater quantities by people who do not have access to a diet consisting of fewer hydrogenated fats, or who often consume fast food. A diet high in trans fats can contribute to obesity, high blood pressure, and a greater risk for heart disease and type 2 Diabetes. For example, a low-income neighborhood in New York City, East Harlem, mostly has fast food restaurants, which might be a part of why 31% of adults in East Harlem are obese compared to 22% citywide and only 9% in the high-income Upper East Side (NYC Department of Health and Mental Hygiene, Eating Well in Harlem: How Available is Healthy Food? 2007)
To minimize the risk of trans fats
- Follow the suggestions in Canada’s Food Guide to Healthy Eating. The guide advises you and your children to choose lower fat dairy products, leaner meats and foods prepared with little or no fat.
- Read the labels on pre-packaged food products. Since December 2005 it has been mandatory in Canada for most foods to list on the Nutrition Facts table the amount of trans fat in the product.
- Also look for the phrase “partially hydrogenated oil” – if you see this phrase in the list of ingredients on the label it means the product contains trans fat.
- Choose soft margarines that are labelled as being free of trans fats or with ingredient lists including fully hydrogenated or non-hydrogenated oil.
- Avoid products made with partially hydrogenated oil.
- Fry foods less often and use healthier oils with a higher proportion of unsaturated fats.
- Do not re-use oil for frying more than two or three times.
- When you eat out, ask about the trans fat content of the foods on the menu.
What foods have trans fat?
These foods often have trans fat:
- Deep fried foods (spring rolls, chicken nuggets, frozen hash browns, French fries)
- Ready to eat frozen foods (quiche, burritos, pizza, pizza pockets, French fries, egg rolls, veggie and beef patties)
- Hard (stick) margarine and shortening
- Commercially baked goods (donuts, Danishes, cakes, pies)
- Convenience foods (icing, puff pastry, taco shells, pie crusts, cake mixes)
- Toaster pastries (waffles, pancakes, breakfast sandwiches)
- Oriental noodles
- Snack puddings
- Liquid coffee whiteners
- Packaged salty snacks (microwave popcorn, chips, crackers)
- Packaged sweet snacks (cookies, granola bars)
Why trans fats are still widely in use?
Trans fats are easy to use, inexpensive to produce and last a long time. Trans fats give foods a desirable taste and texture. Many restaurants and fast-food outlets use trans fats to deep-fry foods because oils with trans fats can be used many times in commercial fryers.
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