Original story published here on May 27, 2004.
Although most people believe that fat in the diet is a bad thing, leading to clogged arteries and other health problems, certain types of fat are necessary for our bodies to function properly, said Manabu Nakamura, a specialist in biochemical and molecular nutrition at the University of Illinois.
In fact, omega-3s and omega-6s are so important to body function that they are called essential fatty acids, and they are critical to fetal development and to skin, nerve, and brain function. Omega-3s can reduce the clotting factors that precipitate stroke and heart disease, and they can lower blood triglycerides, another risk factor of heart disease.
Furthermore, our bodies can’t make these essential fatty acids, so we have to consume them in our diets. “Fatty fish, such as salmon, is a good source of omega-3s, and I recommend cooking with canola or soybean oil. Consumers can already purchase eggs that are rich in omega-3s, and other enhanced products should be available soon,” he said.
Omega-6s can be consumed in pistachios and sunflower seeds or consumed in borage oil or evening primrose oil, available as dietary supplements. Nakamura said it’s important to keep omega-3s and 6s in balance, and he added that genetic modifications to soybeans and other oil seeds are under way that will help us do that.
Saturated fats, on the other hand, found in animal fats and fried and processed foods, are the “bad” fats, implicated in everything from heart disease to breast cancer.
Nakamura has been investigating the way in which essential fatty acids regulate the production of certain enzymes in the liver. “We know that the essential fatty acids help regulate body fat deposition, increasing the body’s use of fat by causing fat-burning enzymes to kick in,” said Nakamura.
“Although it looked promising at first, we are finding that this phenomenon is mostly restricted to the liver, not to fat storage tissue in the body. The liver seems to regulate fat synthesis in such a way that it makes just enough unsaturated fat to promote flexibility in human cell membranes,” he said.
Nakamura is also investigating the way two types of carbohydrate–glucose and fructose– are metabolized in the body. Table sugar, he said, contains about half glucose and half fructose. Most soft drinks contain a lot of high-fructose corn sugar because fructose is sweeter than glucose and makes a better sweetening ingredient in beverages.
“Although it’s still early to talk about the results, one of our animal studies seems to show that fructose may not be as good as glucose for the body. Fructose may actually have a strong effect on whether food is used as energy or stored as body fat,” he said.
Although the metabolism of fat is still not fully understood, scientists know enough to be able to say that some types of fat are beneficial while others cause health problems.
While research continues in Nakamura’s lab and others, he suggests eating one to three servings of fish weekly for the essential fatty acids that our bodies need and avoiding the saturated fats, found in fried and processed foods, that have unhealthy effects on our bodies.