Dietary fat is a vital nutrient that is essential for health. Like other macronutrients, dietary fat is an important energy source for the body. It is also the most concentrated energy source for the body, providing 9 calories/gram vs. 4 calories/gram for both carbohydrates and protein.
Hence, while some dietary fat is essential to provide the essential fatty acids and fat-soluble vitamins which include A, D, E, and K, too much fat can add a significant amount of energy, subsequently leading to weight gain.
Three Main Types
There Are Three Main Types Of Fatty Acids:
All fats have the same basic structure; they are a chain of carbon atoms with varying amounts of hydrogen atoms attached to each carbon. This is important to understand the next piece to this article.
Think of the structure of fats as a school bus; the bus itself is the carbon atom chain discussed above and all the seats are the hydrogen atoms.
If all the carbon atoms are full of hydrogen atoms, the "seats on the bus" are full, and you have a saturated fat. No other atoms can fit onto the structure because there are no "empty seats."
Saturated fats are easy to identify because they are solid at room temperature (butter, shortening, animal fats, etc). Likewise, if there is one "empty seat" on the bus and the rest are full, you have a monounsaturated fat (mono, meaning one).
Mono & Polyunsaturated Fats
Monounsaturated fats are liquid at room temperature (vegetable oils, like olive oil, canola oil, etc). This means there is room to fit more hydrogen because of the one empty space.
Trans fats are another type of fat that occur naturally in some foods, such as dairy products and animal products, but are most commonly added artificially into a variety of commercial products (Table 1). Remember the monounsaturated fats from above; they had the one empty "seat" without a hydrogen atom.
The process of hydrogenation or partial hydrogenation is when food manufacturers artificially add hydrogen to unsaturated fats to provide greater stability and, ultimately, longer shelf life; hydrogenation makes liquid fats solid at room temperature.
The process of hydrogenation was developed in the early part of the last century. It is now used to increase the functionality of the specific food product (ability for margarines to spread easily, increases shelf life and stability, contributes to the creaminess of certain foods, etc).
| The Discovery Of Hydrogenation.
The first patent for the hydrogenation process was issued to William Norman in 1903 as food processors began to lean toward the use of vegetable oils.
This is obviously beneficial for the food companies because it enhances the palatability of foods, increases their ability to remain fresh, and decreases the cost (it is cheaper than using some other types of fats). No one is interested in buying expensive, stale crackers!
The problem is researchers have learned that trans fats have adverse actions on lipid profiles (raise LDL, the "bad" cholesterol), plasma markers of inflammation, endothelial function, and are subsequently associated with an increased cardiovascular disease risk1.
Similar results have been realized for those with preexisting heart disease; it is not just in healthy individuals as was originally investigated2.
|Table 1: Select Foods That Commonly (not always) Contain Trans Fats.|
|Most baked goods||Margarines|
|Cakes||Non-natural peanut butter|
Therefore, with these negative health outcomes clearly correlated to trans fats, it is important to discuss specific foods they may be found in (Table 1), suggested intakes, how to avoid them, and the new labeling laws that will require trans fat be listed on food labels.
Real World Tips
These tips may help provide insight into the world of trans fats.
Is There A Suggested Intake For Trans Fats?
There is no suggested intake for trans fats; however, total elimination of trans fats from the diet would be difficult, since it is contained naturally in some foods. However, it is suggested that the intakes are lowered as much as possible; there is no requirement for trans fats in the diet.
The best way to limit the intake of trans fats is to reduce the amount of processed, prepackaged foods and increase the intake of more natural foods, like fruits and vegetables, for example.
How Can Someone Tell If A Product Contains Trans Fats?
The simplest way is to read the ingredient panel; if hydrogenated or partially hydrogenated oils are listed, it contains some trans fats. In 2006 it will be mandatory for all food manufacturers to list trans fat on their product's nutrition facts panel.
This will be listed on a separate line, under saturated fat. Some manufacturers have already begun making this change.
How Can The Ingredient List Say Hydrogenated Or Partially Hydrogenated, But List 0 Grams Of Trans Fat?
The tricky part is that some products may contain low amounts of trans fats, but still lists zero trans fats on the food label. Remember, if the ingredient list says hydrogenated or partially hydrogenated oils, the food contains trans fats.
However, food manufacturers are allowed to list the amount of trans fats as zero, if, and only if, each serving contains less than 0.5 grams of trans fat.
Keep in mind that this is per serving, so if it's normal to sit down with a container of peanut butter on your lap and eat it by the spoonful, the normally low amount of trans fats in each serving will quickly add up. Of course the calories will too, so this practice is not recommended at all.
Similarly, if a product itself contains less than 0.5 grams of total fat per serving, a footnote must be added stating that the food "is not a significant source of trans fat."
Again, serving size is the crucial component in a situation like this. So read the nutrition facts panel and ingredient lists.
I Have Heard That Butter Is Safer Than Margarine Because Of The Trans Fats. Is This True?
There are a number of margarines on the market that now contain zero trans fats. Remember, trans fats make liquid oils solid at room temperature. Therefore, a simple way to determine if margarine is hydrogenated is to look if it's in a tub or sold a stick.
The tub of margarines are usually lower in trans fats; they are easier to spread and are more fluid than the solid sticks.
There are also some fairly new butter spreads that contain healthier fats, such as flax oil, or other omega-3 fats; these can be a healthier alternative if looking for a butter or margarine type product to use.
The moral of the story is to reduce the intake of prepackaged foods as much as possible. Look for items that do not contain partially hydrogenated or hydrogenated oils.
| A Modern Look At An Old Process.
"If the hydrogenation process were discovered today," Dr. Walter Willett remarked in his Harvard School of Public Health Report, "It could not be adopted by the oil food industry... It's currently the third-highest food-safety concern, ranking only behind the E.coli scare and salmonella."
Since trans fats are found naturally in many foods, it's very difficult to totally eliminate all trans fats in the diet. Doing what you can to reduce the intake as much as possible is highly recommended, though.
This is especially important for those with diabetes, who are already at an increased risk of cardiovascular disease; doing everything possible to reduce this risk is crucial.
Remember there is no dietary requirement for trans fats. This translates to doing 95% of your shopping around the perimeter of the grocery store. There you'll find more natural foods, such as fruits, vegetables, whole grains, fish, etc. and less prepackaged items.
- Lopez-Garcia, E., Schulze, M. B., Meigs, J. B., Manson, J. E., Rifai, N., Stampfer, M. J., et al. (2005). Consumption of trans fatty acids is related to plasma biomarkers of inflammation and endothelial dysfunction. J Nutr, 135(3), 562-566.
- Mozaffarian, D., Rimm, E. B., King, I. B., Lawler, R. L., McDonald, G. B., & Levy, W. C. (2004). trans fatty acids and systemic inflammation in heart failure. Am J Clin Nutr, 80(6), 1521-1525.