Editors at a recent Los Angeles food conference agreed that cutting down on fats was the No. 1 health recommendation in the stories they write. But the types of fat and how they affect the diet are still puzzling to readers.
The most recent introduction of new oil on the market--canola oil, the most unsaturated of polyunsaturated oils--provides the perfect opportunity to talk about oils, what they are, their role in the diet and how they measure up against one another.
The key to the fat issue is its affect on health and its direct link to heart disease.
Since 1958 at least 17 health agencies, including the American Heart Assn. and the National Cancer Institute have called for sweeping changes in the American diet in an effort to reduce heart disease, which claims 500,000 Americans each year.
Most recently the U.S. Surgeon General C. Everett Koop urged Americans to improve their dietary health by reducing their consumption of fat, especially saturated fat and cholesterol.
In his report he urged consumers to reduce total fat intake, especially saturated fat, and to choose foods low in fat and saturated fat. Further, he stated, “Among vegetable fats, those that are more unsaturated are better choices.”
Today Americans consume an average of 37% in fat, more than the upper limit of 30%, and 13% from saturated fat recommended by the American Heart Assn. and the American Cancer Society. Less than 10% saturated fat is urged, however.
Despite a 6% drop in fat consumption in the last six years, fat consumption in the United States is above that consumed by Mediterranean countries, Japan and China where coronary heart disease rates are much lower than those in the United States. Saturated fat has been linked to coronary heart disease, claiming an average of 1,370 people per day. Excessive levels of dietary cholesterol and saturated fat have been shown to significantly increase blood cholesterol levels.
A 1988 survey at the De Bakey Heart Center at Baylor College of Medicine in Houston showed that 56% of 18,000 dietitians and practitioners agreed that saturated fat--and not dietary cholesterol--is the biggest culprit in raising serum cholesterol in the blood, according to Debbie L. Tindle, a registered dietitian and director of the weight management program at Colima Internal Medical Group, Inc., in Whittier.
Where is all the fat coming from?
It comes from oils and fats used in baking and cooking.
Oils that are most unsaturated are best choices, according to health experts.
However, selecting the proper oil for cooking and salads is not enough. “Oils hidden in processed foods pose a problem because the consumer must interpret the label in order to determine the percentage of fat contained in the product,” said Tindle.
The label contains information not only on the percentage of grams fat, but also the type of fat.
Do you know your oils?
We have included a chart showing the percentage of saturated fat for each oil commonly available. Note that canola oil, the newest oil on the market is the least saturated.
All fats are made up of varying combinations of saturated, mono-unsaturated and polyunsaturated fatty acids, but one type of fatty acid usually predominates. The more saturated the fat, the fewer the double bonds and the more hydrogen (firmness at room temperature) they contain.
Two Unsaturated Types
There are two types of unsaturated fats: polyunsaturated and mono-unsaturated fats. Polyunsaturated fats can actually help lower blood cholesterol, thus reducing risk of developing heart disease. Recent studies indicate that mono-unsaturated fats can also help reduce blood cholesterol levels, in particular, the harmful LDL cholesterol (low-density lipoproteins) without affecting the protective high-density lipoproteins (HDL), which are packages of fatty protein. Medical experts believe the cholesterol carried by LDLs is more likely to adhere to artery walls, while HDLs helps remove cholesterol from the body.)
Cholesterol is a soft, waxy substance which is present in all parts of the body, including the brain, nerves, muscles and heart. However, if too much cholesterol circulates in the blood, it can build up on the inside of artery walls, especially in the arteries leading to the heart. This can slow the flow of blood and greatly increase the risk of a heart attack. Before any cholesterol can travel through the bloodstream, it must be attached to lipoproteins.
Polyunsaturated fatty acids are fats that have two or more double bonds--less hydrogenation and are more liquid at room temperature. Corn, sunflower, safflower and soy oils are good examples.
Mono-unsaturated fatty acids contain one double bond, meaning that they have a neutral effect on serum cholesterol and coronary heart disease risk. Recent preliminary studies indicate that monounsaturates may have a favorable effect on good health. Peanut and olive oil are examples of mono-unsaturated oils.
Saturated fat, the fat that can increase the amount of cholesterol produced by the body and has been directly linked to high blood cholesterol, is high in animal foods, such as processed meats (frankfurters and sausages) fatty cuts of red meat and dairy products.
However, certain plant oils, such as coconut oil, palm oil and palm kernel oil are also high in saturated fat (see chart) because they are partially hydrogenated. The more hydrogenated the fat, the more saturated.
Palm kernel oil is slightly higher in saturated fat than palm oil.
Partially hydrogenated oils are generally found in processed food products, such as nondairy creamers, imitation sour cream, crackers, cereals, ice cream and certain frozen desserts, peanut butter and some margarines.
Liquid oils are least saturated, with canola oil, the lowest in saturated fat, the clear winner among them with only 6% saturated fat compared with 79% for palm kernel oil, the highest saturated oil. Like other vegetable oils, they do not contain cholesterol.
Effects of Stearic Acid
Saturated fats generally raise cholesterol. However, some fats, such as corn oil, which contains 13% saturated fat (7% higher than safflower or canola oils) and coconut oil, which contains more than 70% saturated fat, were found not to raise serum cholesterol levels as much as it was thought because of their prominent stearic acid composition, according to Margo L. Denke, MD, of the University of the University of Texas, Southwestern Medical Center at Dallas. Denke’s research centers on serum lipids, including cholesterol.
Stearic acid, one of the four fatty acids (others are lauric acid, myriustic acid and palmitic acid) that comprise saturated fat, was recently found not to raise serum cholesterol levels. Stearic acid is a fatty acid common in cocoa butter, the major fat in chocolate, as well as in beef and pork fats.
Denke also pointed out that monounsaturated fat was just as effective as polyunsaturated fat in reducing serum cholesterol levels.
Monounsaturated fats are found in olive and peanut oils, both of which are neutral in terms of cholesterol formation and neither prevent or cause cholesterol levels to rise.
“Based on these new dietary research findings, the American Heart Assn. and National Cholesterol Education Committee have endorsed a new diet that should contain less than 30% total calories in fat, with less than 10% in saturated fat (7% if 10% is too high), 10% in polyunsaturated fats with the remaining 10% or less in monounsaturated fat,” she said.
Canola oil, the lowest saturated fat and highest unsaturated fat (primarily mono-unsaturated) of any edible oil, with moderate levels of polyunsaturates, is free of cholesterol, as are all vegetable oils. Canola is 94% saturated fat free. With only 6% saturated fat content, canola contains 30% less saturated fat than safflower or sunflower oils, 50% less saturated fat than corn and olive oil, and 60% less than soybean oil, the most commonly used vegetable oil in the United States. (See the cholesterol-fat content chart on this page.
Canola oil, now nationally available in the United States as Puritan Oil, is a cousin of the rapeseed plant that once was used to make lamp oil in ancient Asia. It was grown in Europe as early as the 13th Century and used as feed for cattle.
By the 20th Century, oil from rapeseed was adapted for use as a lubricant for steam engines. Later, during World War II, rapeseed oil became a valuable commodity for maintaining Allied naval and merchant ships. When enemy blockades cut off European and Asian sources of rapeseed, the Allies turned to Canada for fresh supplies. Canada became the leading exporter of rapeseed oil to the United States.
Used Popularly in Canada
About 40% of all oils used for cooking and salad oils in Canada are made of canola. The name canola was adopted by the Canadian seed oil industry to identify the oil recognized by the early 1970s for its nutritional benefits in reducing saturated fat in the diet.
Canola oil is also a source of omega-3 fatty acids, a type of fat contained in trout, halibut and albacore tuna, as well, have been found to lower serum cholesterol levels. They have also shown to be especially helpful in inhibiting the formation of blood clots, which can cause heart attacks.
The American Heart Assn. and American Dietetic Assn. suggest that consumers refrain from taking fish oil capsules, because they are a high source of fat. “Their absorption and utilization is also being questioned,” said Tindle. Moderation is a key.
It’s a mistake, says Tindle, for consumers to select an oil hoping for a major cure. “There is no quick cure, no magic. It’s a matter of making significant and gradual dietary changes to include foods that are high in complex carbohydrates (fruit, vegetables and whole grains) and lower in total fats (including saturated and unsaturated),” she said.
“A good way to know how much fat you are consuming is to remember that 5 grams of fat equal 1 teaspoon fat (butter, oil, peanut butter or margarine). A teaspoon of butter equals one pat. So if a label indicates that there are 15 grams fat in any form in the product you can translate it to three pats of butter,” Tindle said.
“We need specifically to look for grams of fat per serving, remembering that there are 9 calories per gram in fat, compared with 4 grams for carbohydrates and proteins,” said Tindle.
When reading labels, look for total grams fat. Look for polyunsaturated and unsaturated compared to saturated. The desirable unsaturated and saturated fat ratio is 2-to-1 or greater, in favor of unsaturated (polyunsaturated fat).
For more guidelines on reducing fat intake, call the American heart Assn. at (800) 339-7382 for a Dine to Your Heart’s Content Guide and other literature for low-fat living.
Sound nutrition information is also available by calling the American Dietetic Assn. hot line at (800) 621-6429.
Ways to Fight Fat
Tindle suggested other ways of reducing saturated fat:
--Instead of using package microwave popcorn, use air-popped corn prepared in the microwave, but with nonstick cooking spray and butter-flavored sprinkles.
--For egg substitutes, use such substitutes as those that contain no fat. “Not all egg substitutes are equal. Some are high in fat. Read labels,” said Tindle.
--Egg whites are safe and an excellent substitute for whole eggs or commercial egg substitute.
--Substitute fresh vegetables and fruit with plain nonfat yogurt dip in place of chips and dip.
--Nonfat or part-skim (1% or 2% fat dairy products) are safe in moderation.
--Choose lean cuts of red meat, such as sirloin versus prime rib, especially when dining out, suggests Tindle.
--Order sauces on the side.
--Substitute whipped margarine for butter.
--Dark-colored poultry meats, such as chicken and turkey, are higher in total fat than lighter colored breasts of turkey or chicken.
--Choose light-colored fish, such as trout, halibut and albacore tuna in lieu of darker fish, such as salmon, shark, mackerel, bonita or snapper. In fact, it’s a good idea, Tindle said, to eat fish two or three times a week.
--Use imitation butter or vegetable spread in lieu of butter. Some new products contain 10 grams fat per tablespoon and have a 4-to-1 ratio of unsaturated to saturated fat, which is considered safe. “However, remember that even imitation butter is a source of fat, so should be used sparingly,” Tindle said.
--Research at Northwestern University in Chicago found that with a low-fat diet, adding two servings of oatmeal or oat bran can further reduce serum cholesterol by 5%. “Oatmeal is not a quick cure and has to be used in combination with other dietary changes,” Tindle said.
--Whipped butter or other whipped margarine spreads contain less calories and less then 3 gm fat per servings than butter (5 gm fat).
--Remember that 3 grams of whipped butter or margarine is equivalent to 1 teaspoon.