The Skinny on Dietary Fat
By Laurine Brown

For several decades, nutritionists have been telling us to skim off the fat on our plates. We've been told this will help us stop clogging our arteries and protect our hearts, especially if we go light on the saturated and trans fats. And since fat is packed with calories, going “low fat” was also supposed to help us slim down, which would consequently lighten the load on our ailing hearts too. Recently a panel of experts gathered at the American Dietetic Association's Food and Nutrition Conference to debate the latest science on whether “low fat” really works to protect our health, especially our hearts. With heart disease still being America's major killer the need to “get it right” is urgent. While their session "The Great Fat Debate: Is There Validity in the Age-Old Dietary Guidance?”
raised more questions than answers, several guiding points have emerged from over three decades of “low fat” preaching:

o Replacing fat with sugars and refined carbohydrates does more harm than good. When food manufacturers were given the challenge to lower the fat in processed foods, they needed to find a way to keep the flavor and texture. Sugar fit the bill perfectly, and its use soared as fat was skimmed off. Incidentally, industry loved the switch, since added sugar was cheaper than fat, according to Dr. Walt Willet of Harvard University. Unfortunately, loading up with highly refined carbohydrates tends to raise blood levels of a fatty substance “triglycerides.” To make matters worse, the low-fat switch didn't help us slim down. In fact we plumped up. Deceived by the illusion that “low fat” meant “low calorie”, we gobbled even more calories. And we know where that goes.

o Obsession with “low fat” has been a “massive distraction” often leading to illogical dietary choices, claims Willet, in agreement with Dr. Alice Lichtenstein of Tufts University. We became lured by shelves packed with nutritionally dubious, albeit “fat-free”, chips, sodas, gummy bears and more, as we obsessed over adjusting technical components of our diets, like saturated and trans fats. Yet we lost sight of the big picture of wholesome nourishing foods that should be the center of attention of our heart-healthy plates (real foods like vegetables, fruits, nuts and seeds, legumes, fish, whole grains, etc.). In addition low fat diets can rob us of healthy fats. Along with being a storehouse of energy for growth and development, fats are critical building blocks of every cell membrane, they line our brain and spinal cord, they transport fat-soluble vitamins A, D, E and K which are essential for many body functions including vision, bone and blood health, and a strong immune system, and much more.

o The type of fat really matters, even more than the amount. Interestingly, a recent analysis of more than 1.5 million healthy adults found that following a Mediterranean diet (which serves up plant-based foods with over 30% of the calories from fats like unsaturated olive oil and nuts/seeds) was associated with a reduced risk of overall cardiovascular mortality. With only minimal amounts of red meat and high fat dairy, the diet limits saturated fats (those solid fats found in animals). Our bodies can make these saturated fats anyway, and eating a lot of them may raise heart health risks, although the verdict is still out, explains Willet and Dr. Dariush Mozaffarian of Harvard Medical School. On the contrary, some unsaturated fats, like alpha linolenic acid (an omega-3 fatty acid) are essential because they cannot be made by the body and must be consumed in foods like fatty fish, flax seeds, walnuts, leafy green vegetables. They play a role in improving vascular function, reducing inflammatory responses, blood clotting, blood pressure, cardiac arrhythmias, and blood triglycerides, all of which are associated with a risk of heart disease. Similarly, linolenic acid (an omega 6 fatty acid) - found in vegetable and nut oils like sunflower, corn soy, and peanut oil - is essential, aiding cell membranes, blood clotting and blood pressure. (If all this technical jargon is over-the-top for you, just remember: eat vegetables, fruits, nuts and seeds, legumes, fish, whole grains, etc.).
o Trans fats are bad. Ditch them. Period. These man-made fats are created by heating liquid vegetable oils with hydrogen gas, a process called “hydrogenation”. Labeled “partially hydrogenated vegetable oil” these fabrications are solid at room temperature, stable, flavorful, and less likely to spoil. That's a good thing for manufacturers and we find them everywhere in vegetable shortenings, some margarines, crackers, candies, cookies, snack foods, fried foods, and baked goods. But, hands down, health experts agree they're a bad thing for our health: trans fats raise the bad LDL cholesterol in our blood, increasing our risk for heart disease. What should we aim for? Zero. Zip. But that's not really a problem because you won't find any in the foods that are really good for us (again, vegetables, fruits, nuts and seeds, legumes, fish, whole grains, etc.)

o Nutrition science is a work in progress, emerging “bite” by “bite.” These fragmented bites have done a great job of confusing the public, claims Dr. Lewis Kuller of University of Pittsburg. Keep your fork on the big picture. We still have a lot to learn about how manipulating single food components influences health. And “eating should not be a 'therapeutic challenge,'” Kuller remarks. “It should be pleasurable!” We've eaten real foods from the beginning of time and there is amazing consensus by scientists on foods that nourish us. So in a nutshell? Keep the ingredients simple: vegetables, fruits, nuts and seeds, legumes, fish, whole grains, etc. Got it? And for practical tips on healthy fats see Harvard's http://www.hsph.harvard.edu/nutritionsource/, Oldways http://www.oldwayspt.org/mediterraneandiet, and the University of Michigan's Healing Food Pyramid http://www.med.umich.edu/umim/food-pyramid/. Bon appetit.

Know Your Fats
Saturated fats: Solid at room temperature. Mainly animal fats like beef, pork, dairy.
Trans fats: “Hydrogenation” of liquid vegetable oil changes it to a solid at room temperature. In margarines, fried foods, processed snack foods.
Monounsaturated fats (MUFA): Liquid at room temperature. Turns cloudy in fridge. Examples: olive oil, canola oil, peanut, avocados, nuts like almonds, hazelnuts, pecans, and seeds, like pumpkin and sesame.
Polyunsaturated fats (PUFA): Liquid at room temperature. Mainly in vegetable oils (sunflower, corn, soy, flaxseed), fish, walnuts.
Omega 6 fatty acids: An essential PUFA (must come from food). In vegetable nut oils like sunflower, corn, soy, peanut.
Omega 3 fatty acids: An essential PUFA (must come from food). In flax seed, fatty fish, walnuts, leafy green vegetables. (Note: a 4:1 ratio of omega 6:omega 3 is often recommended for heart health. Western diets have 20:1.)

References:
o Barston S, Paul M, Segal M. “Healthy Dietary Fats: The Truth About Fat, Nutrition, and Cholesterol.” Helpguide. Last reviewed April 2010.<http://helpguide.org/life/healthy_diet_fats.htm>
o Harvard School of Public Health. “Fats and Cholesterol: Out with the Bad, In with the Good.” The Nutrition Source. Harvard School of Public Health. 2010. <http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-full-story/index.html>
o Harvard School of Public Health. “Shining the Spotlight on Trans Fat.” The Nutrition Source, Harvard School of Public Health. 2010. <http://www.hsph.harvard.edu/nutritionsource/nutrition-news/transfats/index.html>
o Kuller L, Lichtenstein A, Mozaffarian D, Willet W. "The Great Fat Debate: Is There Validity in the Age-Old Dietary Guidance?” Presentation at American Dietetic Association's Food and Nutrition Conference and Expo, Boston MA, Nov 8, 2010.
o Mayo Clinic staff. “Mediterranean diet: Choose this heart-healthy diet option.” 19 June 2010. <http://www.mayoclinic.com/health/mediterranean-diet/CL00011>
o Oldways. “Scientific Studies on the Mediterranean Diet.” Oldways. Undated. Viewed 16 Nov 2010. <http://www.oldwayspt.org/mediterraneandiet>
o Scott-Thomas C. “Low fat diets could increase heart disease risk, say nutrition experts” Breaking News on Food & Beverage Development - North America. 16 Nov 2010. <http://www.foodnavigator-usa.com/Science-Nutrition/Low-fat-diets-could-increase-heart-disease-risk-say-nutrition-experts?utm_source=AddThisWeb&utm_medium=SocialAddThis&utm_campaign=SocialMedia>
o University of Michigan Integrative Medicine. “Healing Foods Pyramid: Healthy Fats.” Regents of the University of Michigan - University of Michigan Integrative Medicine. 2010. <http://www.med.umich.edu/umim/food-pyramid/fats.htm>