Lyn Nichols column: What's Cookin': Know your oils for a healthy diet
It seems that almost every week new information is reported on the effects of dietary fats and oils on our health. The most current news item was "the government has declared war on fat." Although the dangers of high cholesterol are widely public...
It seems that almost every week new information is reported on the effects of dietary fats and oils on our health.
The most current news item was "the government has declared war on fat."
Although the dangers of high cholesterol are widely publicized, not so much is reported about fats and oils or about the beneficial effects of one form of cholesterol.
Cholesterol is classified as a lipid because cholesterol and fat have similar solubilities.
Structurally, cholesterol is a sterol and is very important for body health because it helps form parts of cell walls, some hormones and bile acids. It is a soft waxy substance that won't dissolve in water (blood), so special carriers called lipoproteins must transport it in the blood. Depending on the density of the lipoprotein (high or low), the cholesterol is called either "good" or "bad" because of the way it acts.
Cholesterol in the blood comes from two sources. It may be consumed in the diet, especially when food is rich in animal products and meat, or it is manufactured in the liver.
The liver makes the bulk of the cholesterol needed by the body, but eating excess saturated fats or trans fats will definitely produce elevated levels.
If cholesterol is linked to a "low-density" lipoprotein (LDL) it tends to form hard deposits on the insides of arteries that clog them and restrict blood flow.
In contrast, cholesterol that is linked to "high-density" lipoprotein (HDL) is known as "good" cholesterol because it tends to carry cholesterol away from the arteries and back to the liver where it is processed and passed from the body. High HDL levels protect against heart attack.
Natural fats and oils are structurally different from cholesterol and are formed when fatty acids bind to glycerol to form fat molecules.
The fats in foods are mainly of two types -- saturated where all the available spaces in the fatty acids are filled with hydrogen atoms, or unsaturated, where some of the available spaces are not filled by hydrogen atoms.
Furthermore, the unsaturated fatty acids are divided into those with many empty spaces (poly) or a single empty space (mono). These distinctions are listed on the labels of fats and oils purchased in the market and have distinct implications for a healthy diet.
Most saturated fats come from animal sources such as meat, egg yolks, butter and other dairy products. They will raise cholesterol levels in the blood more than anything else except for the unusual plant oils, coconut and palm, which are also saturated.
Saturated fats are usually solid at room temperature in contrast to unsaturated fats (oils) which are liquid at room temperature.
Polyunsaturated (corn oil, safflower oil, sunflower seed oil, etc.) will remain liquid even in the refrigerator. Monounsaturated oils (canola and olive) will firm up when chilled.
Alert shoppers will note that sometimes the amounts of fats on food labels don't add up -- the total fat is greater than the sum of the saturated, polyunsaturated and monounsaturated.
The reason is that trans fats, fats formed when hydrogen atoms are forced through vegetable oils, are often not included on the labels. Until recently, they have been difficult to measure.
The purpose of hydrogenation is to create a more solid product that is spreadable, has a longer shelf life and can be molded into sticks. This is how margarine is created. Unfortunately, trans fats, like saturated fats, but to a lesser degree, tend to raise blood cholesterol and the "bad" low-density lipoproteins.
The good news is that both polyunsaturated and monounsaturated oils help to keep blood cholesterol down and reduce cholesterol deposits in artery walls.
Monounsaturated (canola and olive oil) are the most efficient at lowering the low-density lipoproteins in the blood and keeping the high-density lipoproteins at the same levels.
Canola and olive are both excellent cooking oils. When using canola for frying foods, for example, french fries, the product has a clean potato taste pleasing to most palates. The highest grade of olive oil, cold-pressed extra virgin, adds a delicate flavor to food but the lower grades of olive oil impart a more intense olive flavor.
To help win the "declared war on fat," use fats, oils and hydrogenated shortenings sparingly and cook with vegetable oils (corn, canola or olive) whenever possible.
Remember that coconut and palm oil are high in saturated unhealthy fat even though they contain no cholesterol. Sauté food with olive oil instead of butter, use olive oil in salad dressings and marinades, and use canola oil when baking.
Snack on nuts rather than potato chips. Prepare fish such as salmon, tuna or mackerel, instead of meat two or three times a week -- they contain monounsaturated and omega-3 fats.
And, finally, remember to eat your fruits and vegetables and keep your meals colorful.
For more in-depth information, consult the American Heart Association Web site www.americanheart.org .
Lyn Nichols hosts "What's Cookin'?" weekdays on WDAY-TV. Her column appears Sundays and alternate Wednesdays in The Forum. She can be reached at PO Box 2466, Fargo, ND 58108, or e-mail, email@example.com