Tuesday, August 21, 2007

The Facts About Fat

Below is an article from August 2007 issue of Cooking Light magazine written by Maureen Callahan, MS, RD. Cooking Light is a great resource for healthy cooking, always providing healthy alternatives to make every recipe more nutritious by substituting ingredients and recommending different methods of cooking. Cooking Light is not only for the inspired chef. They also provide interesting facts about a variety of food, beauty tips, and guideline for healthy living.
In this article Maureen Callahan provides the good, the bad, and the ugly, on the various fatty acids to include how much to eat, the effects that fat has on our bodies, and the source of each type of fat. She also brushes upon the trans-fat ban that has recently taken effect in New York City. "It's just a matter of time before tran fat disappear from the American landscape," says Maureen Callahan, MS, RD.

The Facts About Fat
Trans Fat Bans have helped bring awareness to the many roles other fats play in our diets

From curbside snack carts to four-star restaurants, New York City chefs have until next year to rid their kitchens of trans fat. Its a bold move but a necessary one, according to city health officials.

"When you look at the evidence, there's no question artificial trans fat increases the risk of coronary heart disease," says Sonia Angell, MD, director of cardiovascular disease prevention and control at New York City's Department of Health. "The most conservative estimates show that the replacement of these fats with heart-healthy alternatives can decrease coronary artery disease risk by six percent, and it is likely even higher." In fact, a recent Harvard University study showed that women with low blood levels of trans fat are three times less likely to develop heart disease.

The Big Apple's impending trans fat ban is making other cities food companies and scientific experts pay closer attention to the increasingly complex relationships between dietary fat and health. Here's the latest on fats, including where each is found , what it does, and how much or how little to eat.

Trans Fat

There are two types of trans fat-the kind that occurs naturally in small amounts in animal products, and the artificial kind produced by adding hydrogen to liquid oils so they remain solid at room temperature, which helps extend the shelf life. So far no studies have examined how natural trans fat impacts health, but the artificial kind raises levels of LDL("bad") cholesterol and lowers HDL ("good") cholesterol, raising the risk of heart disease.

Where it's found: Most commercially produced fried foods, baked goods, and stick margarine are made with artificial trans fat. Natural trans fat can be found in red meat, butter, milk, and cheese.

How much to eat: As little as possible. The American Heart Association (AHA) suggests limiting trans fat to less than one percent of your daily calories, about two grams if you follow a 2,000-calorie-per-day plan. That figure includes artificial trans fat as well as natural, since natural trans fat sources are often high in another type of fat linked to heart-disease risk factors-saturated fat. "If you're mindful that you want to decrease both trans fat and saturated fat, you're in a good position. I think some people are so focused on trans fat that they forget about saturated fat," says Alice Lichtenstein, DSc, director of the Cardiovascular Nutrition Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging in Boston.

Latest News: The Food world is working at warp speed to find replacements for artificial trans fat. In addition to New York, eight other large American cities-including Los Angeles, Philadelphia, and Boston- have legislation pending to limit or ban artificial trans fat. "It's just a matter of time before these fats virtually disappear from the American landscape," says William Connor, MD, a researcher at Oregon State Health Sciences University.

Saturated Fat

Saturated fat raises LDL cholesterol and sets the stage for heart disease by encouraging the formation of plaque in arteries.
Where its found: Animal products like whole milk, cream, butter, lard, and fatty cuts of meat. Also a component of cocoa butter and tropical oils (palm, palm kernel, and coconut).

How much to eat: Less than 10 percent of your total calories per day (20 grams if you eat 2,000 calories) is a good starting point. For optimal heart health, the AHA recommends seven percent (16 grams).

Latest News: Just one meal high in saturated fat may damage blood vessels and hinder the ability of HDL cholesterol to protect arteries. Normally, HDL guards blood vessels from inflammation that contributes to artery clogging plaque, says Stephen Nicholls, MD, cardiologist at the Cleveland clinic foundation. Not so after a meal high in saturated fat. When Nicholls and colleagues fed 14 healthy volunteers two meals of carrot cake and a milk shake- one made with highly saturated coconut oil and one with polyunsaturated safflower oil-two things happened: The ability of blood vessels to expand and contract (a sign of healthy arteries) and the anti-inflammatory action of HDL were impaired for as much as six hours after the high saturated fat meal. In contrast, when the cake and milk shake were made with polyunsaturated fat, arterial and HDL functions improved. Just how much saturated fat was in that test meal? We likened it to people eating a double cheeseburger, fries, and a shake, which unfortunately, is not that uncommon of a meal," Nicholls says.

Polyunsaturated Fat

This type of fat helps to reduce blood cholesterol levels when substituted for saturated fats. One variety, omega-3 fatty acids, also helps lower blood pressure, control inflammation, and protect against irregular heartbeats.

Where it's found:Vegetable oils like safflower, sunflower, sesame, corn and soy, and nuts and seeds. Omega-3's are found in fatty fish, such as salmon and mackerel, flax seed, and walnuts.

How much to eat: Authorities say 40 to 78 grams in a 2,000-calorie diet should come from fat, polyunsaturated and monounsaturated fats comprising the bulk. However, there is no specific recommended amount for either.

The AHA puts omega-3s in a separate category and suggests two to three meals of fatty fish a week. Two components of omega-3 fatty acid molecules have different benefits: EPA (eicosapentaenoic acid) helps alleviate arterial inflammation and prevent blood platelets from clumping together, while DHA (docosahexaenoic acid) is valuable to the retina and brain. Plant sources of omega-3s confer heart-health benefits similar to those of other foods rich in polyunsaturated fats, but because the chemical structure of the omega-3 fatty acid they contain (alpha-linolenic acid, of ALA) is different, the body does not convert it as readily to EPA or DHA, Connor says.
Latest News: Two studies from the University of Pittsburgh suggest omega-3s found in fish may help improve mood and increase gray matter in the brain. In the first, researchers demonstrated that people with high blood levels of omega-3s tended to be more agreeable and less likely to report mild symptoms of depression than those with low levels. In the second study, researchers uncovered a possible mechanism behind the mood differences: people with high blood levels of omega-3s have more gray matter in the areas of the brain linked to mood. Although preliminary, the findings provide increasing support for including omega-3s in a healthful diet.

Monounsaturated fat

Monounsaturated fat helps lower blood cholesterol levels when substituted for saturated fat in the diet.

Where it's found: Olives, avocados, and olive, canola and peanut oils.

How much to eat: Again, roughly two-thirds of the fat you eat should be unsaturated, either monounsaturated or polyunsaturated.

Latest news: Monounsaturated fat may help protect against heart disease and diabetes, particularly among people with a cluster of conditions-insulin resistance, high blood pressure, high cholesterol levels, and big waistlines-referred to as metabolic syndrome. A recent Italian study put 180 men and women with metabolic syndrome on either a low-calorie Mediterranean-style diet rich in monounsaturated fats, fruits and vegetables, and whole grains or a diet of 30 percent of calories from any type of fat. At the study's end two years later, half of the subjects who followed the Mediterranean-style diet were no longer diagnosed with metabolic syndrome. "Compared to their baseline values the Mediterranean group had a significant increase in HDL and a decrease in both triglycerides and blood sugar, all good changes," says Kathy McManus, MS, RD, of Harvard's Brigham and Women's Hospital in Boston.

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