Thanks to those of you who answered my poll on my previous post, Not All Fats are Created Equal. The ways we process foods these days blurs the lines as to what a food actually is, and there can be some confusion. In essence, the type of fat is linked to the binding of fatty acids and the amount of hydrogen in the bonds. The University of Cincinnati has an excellent description of the structure of fatty acids on the website for it’s introductory biology course. Trans fats are actually a substitute for saturated fats—they are unsaturated fats that have been partially hydrogenized, which turns them into a saturated fat, so the answer to the poll question was “yes.” Good job!
I have a cynical view of how fats are presented to us, so I’ve clumped fats into these five categories: the good, the pretty good, the bad, the ugly, and the scary. I think it’s easier to think of them that way, but that does give away my bias.
Before any discussion of fats, though, you need to have a quick and basic understanding of cholesterol.
Cholesterol
Cholesterol is produced by the liver as well as introduced into the body by dietary fats. When things get out of control with how your body deals with cholesterol, you have to watch your intake of both cholesterol and fats. The consensus is that your cholesterol level is more a function of the kinds of fats you eat, rather than the cholesterol-containing foods you eat. However, some bodies cannot balance out their production of cholesterol with that of dietary cholesterol. If you have such a condition, it’s important to talk to your doctor or a certified nutritionist about this before eating food that inherently contains cholesterol.
There are basically two kinds of cholesterol:
- High-density lipoproteins (HDL), the “good” cholesterol, has been found to protect against heart attacks. Low levels of HDL cholesterol has been linked to an increase in heart disease.
- Low-density lipoproteins (LDL), the “bad” cholesterol, has been found to build up plaque in the artery walls and is linked to stroke and heart disease.
The kinds of fats you eat affect the cholesterol levels in your body.
Good: Monounsaturated fats have the effect of lowering “bad” cholesterol even though they do not raise “good” cholesterol. They include olive oil and canola oil as well as a number of nuts, such as walnuts and avocados. The oils can be identified because they are liquid at room temperature, although some solidification at cold temperatures, such as those found in the refrigerator, can occur. It’s advised that most of the fats eaten should come from monounsaturated fats, but remember that you should limit fat intake to 20–35% of your total calories ingested.
Pretty good: Polyunsaturated fats lower “bad” cholesterol, but also lower “good” cholesterol. These fats include safflower and corn oils, and are also liquid at room temperature as well as in cool temperatures. Omega-3 and -6 fatty acids are included in this group. They can be found in most seafood, and are thought to decrease the contribution of fats toward plaque formation in the arteries. Polyunsaturated fats should take up a large portion of the fats consumed.
Ugly: Saturated fats lower the “good” cholesterol and raise “bad” cholesterol, and is linked to heart disease. They typically come from animal products, but also include palm and coconut oils, and are solid at room temperature. Consumption of saturated fats should be limited to less than 10% of total caloric intake.
Bad: Trans fats also lower “good” cholesterol and raise “bad” cholesterol. In fact, they are linked to lowering HDL and a higher risk of heart disease even more than saturated fats. They are synthesized by adding hydrogen to vegetable oils, and are “hydrogenated.” This makes liquid oil more solid and lengthens the shelf-life of the product. While trans fats can be found naturally occurring in small amounts, they can typically be found in many commercially baked goods, such as cookies and crackers, in fried foods, and many margarines and shortenings. Although the nutrition facts panel may list trans fats as 0% or 0g, there may be up to half a gram of trans fats (0.5g) per serving and still list 0g trans fats*. The American Heart Association recommends that less than 1% of your total caloric intake comes from trans fats; I try to avoid them completely. Always check the ingredients for “hydrogenated” or “partially hydrogenated” oils.
Ironically, Smart Balance Buttery Spread just came out with a commercial advertising that they are as “close to zero trans fats as possible” (at .07g)
Scary #1: Fat substitutes, such as Olean® (Olestra), typically aren’t covered in discussions on fats because they are not fats (they’re substitutes). Olestra is the one that most of us have heard about—probably because in 1995 an FDA review group “…recommended that products containing olestra bear a label statement about the food’s potential to cause intestinal discomfort or a laxative effect, without suggesting that the product is intended for use as a laxative.” But this isn’t the only fat substitute, so I’ll deal with them in a future post.
Scary #2: Interesterified fats, like trans fats, are designed to be an alternative to saturated fat and also extend the shelf life of food products. They have similar side-effects as trans fats but have been found to affect glucose and lipoprotein metabolism. The American Heart Association states that more studies are needed, and I’m having problems finding labeling regulations on the FDA website. Although I am sure there are more companies that produce them, I could only find that Archer Daniels Midland Company (ADM) produces interesterified fats as Novalipids™. Hopefully we’ve learned our lesson from the trans fat fiasco and will deal with interesterified fats cautiously. Look for them in the ingredient list and try to avoid them.
Does anyone else know about interesterified fats or their regulation in our foods? Let us know!
Also, a quick-reference table comparing the above fats will be coming soon.
*FDA Electronic Code of Federal Regulations, § 101.9(c)(2)(ii).
