While limiting your fat intake is an important strategy for better weight control, the type of fat you eat is equally important to your pursuit of optimal health. Why? Certain kinds of fats are harmful and should be avoided, while others are actually necessary for life. Here are the basics of what you should know about choosing fats.
Best known for its role in promoting heart disease, saturated fat raises blood cholesterol levels, thus contributing to clogged arteries. The vast majority of saturated fat in most people's diets comes from high-fat meat and dairy products, so simply switching to low- and no-fat alternatives can go a long way towards reducing your intake of this harmful substance. Coconuts and tropical oils such as palm kernel oil also contain saturated fats, and should be limited as well.
A similar kind of fat that you should be aware of is hydrogenated fat. This is a chemically altered fat that is produced by adding hydrogen to liquid vegetable oils. This process, called hydrogenation, transforms the liquid vegetable oils into solid margarines and shortenings. While hydrogenation improves the cooking and baking qualities of oils, and extends their shelf life as well, it also makes the oils more saturated and creates undesirable by-products known as trans-fatty acids, or trans fats. And trans fats act much like saturated fats to raise levels of LDL, or "bad" cholesterol, and at the same time lower levels of HDL, or "good" cholesterol. The best way to trim your intake of trans fats is to avoid hard margarines as well as baked goods, snack foods, and other products that contain hydrogenated vegetable oils.
Monounsaturated fats found in olive oil, canola oil, avocados, and some nuts are the fats of choice these days. Unlike saturated and hydrogenated fats, monounsaturated fats do not promote heart disease. In fact, in Mediterranean countries where olive oil is used liberally, the incidence of heart disease is much lower than it is in countries like the United States. Keep in mind, though, that olive oil is just one component of the Mediterranean diet. This style of eating also includes generous amounts of fish, fruits, vegetables, legumes, and garlic, and contains less sugar, red meat, and processed foods than Western diets. It is the total Mediterranean diet not just the olive oil that is responsible for protection against heart disease. Realize, too, that like all fats, monounsaturated fats are a concentrated source of calories.
Some of the most exciting research in recent years centers on polyunsaturated fats especially on two classes of essential fatty acids known as omega-6 and omega-3 fats. Why are these fats attracting so much attention? Omega-6 and omega-3 fats have very powerful and very different effects in the body. For instance, omega-6 fat promotes blood clotting, while omega-3 fat inhibits clot formation. Omega-6 fat acts to raise blood pressure, while omega-3 fat helps to lower blood pressure. Because of their powerful and opposing effects, the balance of these essential fats in your diet can greatly affect your susceptibility to a variety of disorders.
Researchers believe that humans evolved on a diet that provided about equal amounts of these two fats. But over time and especially during the twentieth century our diets changed dramatically. First, technology made it possible to mass-produce vegetable oils, and our food supply became inundated with polyunsaturated vegetable oils that are concentrated sources of omega-6 fat, and practically devoid of omega-3 fat. Then, farmers began feeding livestock grains, which made the animals fatter as well as higher in saturated and omega-6 fats. To make matters worse, manufacturers began using omega-6-rich oils as the main ingredient in foods like mayonnaise, margarine, and salad dressings. As a result, the ratio of omega-6 to omega-3 fat in the diet rose from about 1 to 1 to as high as 20 to 1, creating an imbalance that alters body chemistry to favor the development of heart disease, cancer, inflammatory and autoimmune disorders, and many other health problems.
Fortunately, it is a simple matter to bring your intake of these two fats into balance. How? Eat fish at least twice a week, since fish is a rich source of especially potent omega-3 fatty acids. Also include generous amounts of green plant foods in your diet, as they, too, supply omega-3 fats. For most of your cooking needs, choose oils like canola, olive, walnut, and soybean, which have a healthier balance of omega-6 to omega-3 fats than do oils like safflower, sunflower, and corn. When purchasing products like mayonnaise and salad dressings, choose lower-fat versions, and read the label to see which oils they contain. Finally, try using omega-3-rich flaxseeds (page 23) in baking, or sprinkle some over your cereal. These simple strategies will help you consume both a healthy amount and a healthy balance of fats.