By Yolanda Smith, BPharm
Trans fat is a type of unsaturated fat that can be produced when unsaturated fats, like those found in vegetable oils, are processed to resemble the physical properties of saturated fats, like butter.
The most common example of a food product with trans fat is margarine, which is created from vegetable oil through a chemical hydrogenation reaction. There are trans fats present in many food products, however, and they are also commonly used in the cooking processes of many food chains.
Trans fat is known to have an adverse effect on health, particularly as it raises the risk of coronary heart disease. As a result, food manufacturers have been working towards using fewer or eliminating trans fat and the public should avoid consumption of trans fat where possible.
Natural Trans Fat
The vast majority of trans fats present in the world have been produced through chemical processes for commercial purposes, however some trans fat normally occurs in natural substances.
For example, approximately 2-5% of the fat found in the milk and body fat of cattle and sheep are trans fats, such as conjugated linoleic acid (CLA) and vaccenic acid.
Natural trans fats occur in very small concentrations in respect to other types of fat, however, and trans fat from commercial food forms the majority of consumed trans fat by the public today.
Rationale for Trans Fat in Food Products
When the process of converting unsaturated vegetable fats to saturated vegetable fats was discovered early in the twentieth century, it presented a valuable opportunity for food producers.
Partially hydrogenated fats could be manufactured in a cost-effective manner and held particular benefits over traditional fat products. An example of this is the readiness of margarine to be spread, immediately upon removal from the refrigerator, which offers greater convenience to the consumer. These products also usually have a longer shelf life.
As a result, partially hydrogenated fats that contain trans fat largely replaced natural fats and oils in many food industries throughout the twentieth century, including baked goods, snack foods, fried food and fast food production.
Trans Fat Content in Food
Trans fat is produced in the manufacturing process of partially hydrogenated plant fate, but the concentration of trans fat can vary with up to 45% of total fat trans fat content.
The fat found in baking shortening is generally composed of 30% trans fat, while some margarine may contain 15% trans fat. When it is considered that naturally occurring trans fat is found at concentrations of 2-5%, these figures are alarming.
Trans fats have been routinely used for deep-frying in fast food restaurants as they have a longer shelf life and are more cost effective than conventional oils. The fats used in restaurants in different locations can vary greatly due to the regulations enforced in the region.
Early in the 21st century, non-hydrogenated vegetable oils with significantly longer lifespans were introduced to the market, offering a suitable alternative to products containing trans fat. As a result, many food manufacturers and producers have been making the change to produce food that contains less trans fat.
Breast Milk Trans and Fat Consumption
Research has shown that trans fat content in human milk is related to the maternal consumption of partially hydrogenated oil. Additionally, infant consumption of trans fat in milk has a direct effect on the fat circulating in their bloodstream and is presumed to have negative health effects.
Just as dietary intake of trans fat differs in countries of the world, the concentration found in breast milk and infants also fluctuates. Spain and France have lower levels of trans fat, with 1% and 2% respectively whereas human milk in the United States contains 7% trans fat on average.
Last Updated: Jun 14, 2015