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Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.

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Knowledge is Power العلم نورٌ

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July 10, 2008

Healthy oils and healthy fats


Healthy Oils, Healthy Fats
Good fats are emerging as one of the hottest new functional foods.
By
Peter JaretWebMD Feature
Reviewed by
Brunilda Nazario, MD
When Americans started to pack on pounds a few decades ago, fat was fingered as public enemy number one. “Low-fat” became the rallying cry for healthy eating. And so began one of the most misguided public health campaigns in history.
Most of us know by now that the main villains are saturated fats, found chiefly in meat and high-fat dairy products, and trans fats, found in fried foods, cakes, crackers, and some margarines. They raise total cholesterol levels and gum up arteries. Unsaturated fats, which mostly come from plants and fish, are essential to good health.
But even the good fat/bad fat message is turning out to be more complicated than nutritionists once thought, as researchers explore the health effects of the many different kinds of fatty acids. With evidence emerging that healthy fats not only improve cholesterol and triglyceride levels but also reduce inflammation, fats are emerging as one of the hottest new functional foods.
Polyunsaturated vs. Monounsaturated: Choosing the Healthiest Oil
“We can now say unequivocally that unsaturated fats protect against heart disease,” says John Brunzell, MD, professor emeritus in the division of metabolism at the University of Washington, Seattle.
· In an analysis of data from 60 trials, researchers at Maastricht University in the Netherlands found that cutting back on carbohydrates and consuming more polyunsaturated and monounsaturated fats decreases the level of harmful LDL cholesterol and increases protective HDL cholesterol.
· The more recent Optimal Macronutrient Intake Trial for Heart Health (OmniHeart) study showed that a diet rich in unsaturated fats also lowers blood pressure and reduces overall heart disease risk.
Debates have long raged about whether monounsaturates or polyunsaturates have the edge. The Maastricht University study found a slight advantage to polyunsaturated fats for improving the ratio of HDL (good cholesterol) to total cholesterol. But studies of people with diabetes, who have a high risk of heart disease, conducted at Trinity College in Dublin suggest that monounsaturated fats may offer more protection.
In the end, few of us keep count of grams of monounsaturated or polyunsaturated fat, of course. All edible oils are a blend of these two types of fat. Edible oils also contain at least some saturated fat. The amount of saturated fat in oil may be a more important consideration than the ratio of monos to polys.
· Olive oil, for instance, contains 73% monounsaturated fat, 11% polyunsaturated fat, and 14% saturated fat.
· Soybean oil, by contrast, is 24% mono, 61% poly, and 15% saturated fat.
· Canola oil wins high marks. It’s 62% monounaturated, 32% polyunsaturated, and only 6% saturated fat -- by far the lowest among edible oils.
A 2007 study by researchers at the Department of Food Science and Human Nutrition at the University of Illinois, Urbana-Champaign found that substituting canola oil for other vegetable oils and canola oil-based margarine for other spreads could significantly lower saturated fat levels in the American diet. What’s more, canola oil is also a good source of omega-3 polyunsaturated fats, which may be especially crucial to good health.
Of course, studies of the Mediterranean diet suggest that olive oil, which has a very different fatty acid profile, also offers potent protection against heart disease.
“In fact, there are many healthy unsaturated oils,” says Brunzell. “The issue isn’t choosing the healthiest, but encouraging people to use the ones they like.”
Omega-6 Versus Omega-3: Finding the Healthiest Balance
Polyunsaturated fats can be subdivided into omega-6, found in most plants, and omega-3 fatty acids, found predominantly in fish oils. Many researchers think the balance of these two fats may be the most critical measure of a healthy diet.
Currently, the modern diet is tipped heavily toward omega-6s, says Floyd Chilton, PhD, director of the Bontanical Lipids Center at Wake Forest University. “In the average western diet, the ratio is about 9:1 omega-6s to omega-3s. In some individuals we’ve studied, the ratio is as high as 40:1.”
No one knows what the optimum balance should be. According to Chilton, there’s good evidence that the diet of hunter-gatherers -- and thus the diet our bodies evolved to eat -- had a ratio of 2:1 omega-6s to omega-3s.
Restoring something close to that balance could help fight many of the chronic diseases that plague us, Chilton believes. “Omega-6s fatty acids regulate genes that spark inflammation. And inflammation is increasingly being seen as the central process in heart disease, diabetes, arthritis, and other chronic health problems.”
Omega-3s, in contrast, tamp down inflammation and have been linked to many health benefits, including lowering triglyceride levels, guarding against dangerous irregular heart rhythms, and preventing plaque from breaking away from the lining of arteries. A 2006 review in The American Journal of Cardiology found that consuming omega-3s from fish, nuts, or soybean oil can lower cardiovascular risk by as much as 60%.
Contains Omega-3s: Can You Believe the Latest Health Claim?
The good news about omega-3s hasn’t been lost on food manufacturers. “Contains omega-3s” is the hottest new health claim on packages.
In 2000, omega-3 supplementation was a $100 million business, according to Chilton. By 2007, it had ballooned into a $3 billion business, which is expected to more than double by 2011.
Unfortunately, the omega-3s touted on the packages today are usually in the form of flaxseed oil, which is not as biologically available as omega-3s from fish oil. More and more manufacturers are beginning to switch to fish oil, according to Chilton, using a double encapsulation technology that prevents the flavor and smell from affecting food. The functional food industry is also working overtime to develop plant sources of omega-3s that are biologically active.
But not everyone’s sold on the idea that a healthy diet should be built on fortified foods and supplements. “There’s a long history of nutrients being taken out of food and put into pills, from vitamin E to beta carotene, and the results have not been encouraging,” says Brunzell. He thinks people should be encouraged to get their nutrients from foods that are known to be healthy -- fish, nuts, fruits and vegetables, and whole grains.
Cholesterol-Lowering Spreads: What You Should Know
One of the first fat-based functional foods to hit the market were spreads and margarines made with substances from plants called sterols and stanols, which have been shown to lower LDL. These substances are similar in size to the cholesterol molecule but they work by blocking the absorption of cholesterol in the intestines. Plant stanols or sterols occur naturally in foods such as fruits and vegetables, but not in high enough concentration to have an impact on cholesterol. So they are concentrated and added back to select foods.
The National Cholesterol Education Program recommends eating 2 grams of plant sterols or stanols a day if you have high cholesterol. But for people who do not have high cholesterol, both the NCEP and the American Heart Association do not recommend foods enriched with plant sterols. Instead, those people should get the plant sterols found naturally in vegetables and fruits.
“Most people can get the same benefits from using unsaturated oils and eating plenty of vegetables, which are the natural source of sterols and stanols,” says Brunzell.

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