Who would have thought that an 1890's French born Nobel laureate recipient and a German scientist would be connected to our current day health dilemma related to the consumption of trans fatty acids? This much talked about health concern can be traced to a brilliant French born scientist named Paul Sabatier's. His painstaking research on the use of finely-divided metal hydrogenation catalysts subsequently lead to the formulation of oil hydrogenation and later to the invention of margarine. While Sabatier's focus was only on the hydrogenation of vapors, his German food chemistry counterpart, Wilhelm Normann, demonstrated in 1901 that liquid oils could be hydrogenated. He patented the process in 1902 and in 1909, Procter & Gamble acquired the US rights and they began marketing the first hydrogenated shortening made from cottonseed oil. This product would reach the grocery stores shelves and the consumer would recognize it as Crisco.
What are trans fatty acids?
To understand what makes a trans fatty acid so harmful we must first define its chemical origin. Trans fats are unsaturated fatty acids with at least one double bond. Note that there are two groups of fatty acids--saturated and unsaturated. The term unsaturated refers to the presence of one or more double bonds between carbons whereas a saturated fatty acid has all bonding positions between carbons occupied by hydrogen. A general principle about these acids is that vegetable oils contain more unsaturated fatty acids and animal fats contain more saturated fatty acids. We commonly hear about saturated fats which come from animal sources as well as tropical oils such as coconut and palm oils. These fats raise the levels of LDL cholesterol as opposed to unsaturated fats which come from vegetable oils and in general practice does not increase cholesterol levels and may even reduce them.
Unfortunately, when unsaturated vegetable fats are subjected to the process of hydrogenation by forcing hydrogen atoms into the holes of unsaturated fatty acids, a new type of fatty acid is formed. This new type of fatty acid is called trans fatty acid and the end product that we use on our toast is called margarine. The food industry is very attracted to these partially hydrogenated fats because of their long shelf life, their adaptability to high heat cooking processes such as deep-frying, and their ability to enhance the palatability of baked goods and sweets.
What's the harm with trans fatty acids?
A couple of decades ago the bad news from the scientific community started pouring in on the unhealthy side effects of saturated fats. In an effort to stem the tide of these saturated fats being used in the manufacturing process the food industry switched to unsaturated fatty acids that had undergone hydrogenation. The practice of substituting partially hydrogenated vegetable oils for saturated fats in processed foods set the stage for the introduction of relatively large amounts of trans fatty acids into the typical diet.
Increased concern over the correlation between consumption of trans fatty acids and coronary artery disease began in the early 1990's. Harvard School of Public Health researchers helped raise the awareness of the deleterious effects of trans fat consumption and coronary heart disease. They were instrumental in the push to have trans fatty acids listed on food labels to alert consumers of the health risk. Finally, in January 2006, new FDA labeling guidelines mandated that trans fat must be listed on food labels in the United States. This is significant because prior to this legislation, no other food label change has been enacted since 1993. This labeling change has helped educate the public on the awareness of trans fat and health risks but it still remains one of the most common ingredients in processed foods. One hidden fact is that many products, including fast foods, have trans fats and are exempt from the labeling laws. For example, if a person consumes one sweet roll for breakfast and a large order of onion rings for lunch they would be eating around 10g of trans fatty acids. This equates to approximately 90 calories, or 5% of the total calories in fat and includes very little food.
Metabolic studies have shown that trans fats have adverse effects on blood lipid levels increasing total cholesterol and LDL ("bad cholesterol") levels and reducing HDL ("good cholesterol") levels. In other words, trans fatty acids are detrimental to cardiac health and the combined effect is double that of saturated fatty acids.
Research published in 1997 by The Nurses Health Study further defined the relation between trans fatty acid intake and risk of coronary disease. The study suggested that, "replacing 5 % of caloric intake from saturated fat with unsaturated fat was associated with a 42 percent lower risk of cardiac disease whereas replacing 2 percent of energy from trans fat unsaturated fat with calories from unhydrogenated, unsaturated fats was associated with a 53% lower risk.
Are there any heart healthy oils?
Yes, there are two catagories of heart friendly oils which contain monounsaturated and polyunsaturated fatty acids. These oils originate from vegetables or other plant sources and can actually reduce total cholesterol and increase HDL cholesterol levels. Consumer demand for canola, peanut, olive, flax, corn, safflower, and sunflower oils have steadily increased in the past several years with grocery stores stocking extra shelves of these products. The bonus with these oils is the essential fatty acids they provide which the body cannot make itself. So on you next visit to the grocery store take a good look at the labels of the products you choose. This may just be the best read of your life.
By Valerie Houghton Registered Dietitian
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