Yes, some of the fats in food are actually good for you. It’s true – NOT all fat in food is evil! Some fats have such amazing health benefits that you should seek them out and eat them every day–such as the omega 3 fats found in fish. But while we know some fats are important to include in our diet, it has become even clearer with recent research that there are types of fat that increase your risk of heart disease, that’s the saturated and the trans fats, and they should definitely be avoided. In this article we will review the major sources of trans and saturated fat as well as what you can do to avoid them. Next month we’ll cover the amazing Omega 3 fats and other food fats with important health benefits and how to find them.

Why are saturated and trans fats considered a threat to heart health?

Studies, such as the landmark Seven Countries study, compared intake of total fat and saturated fat to heart disease risk in different countries and concluded that it was saturated fat intake more than total fat that increases risk for heart disease. Other research evidence (from carefully conducted studies where volunteers were fed special diets) shows that increasing saturated fat intake raises the Low Density Lipoprotein Cholesterol (LDL). LDL is the type of cholesterol in your blood that raises heart disease risk. Human feeding studies show that trans fat maybe worse than saturated since it not only raises the bad LDL cholesterol but it also decreases (worsens) the level of High Density Lipoprotein cholesterol (HDL). Decreasing HDL is considered very detrimental, because low levels, especially below 40 mg/dl, are linked to much higher heart disease risk. Studies in large groups of people confirm the relationship between eating a diet high in trans fat and the risk for heart disease.

What are saturated fats and trans fats?

All the fats we eat are mixtures of different types of fatty acids. Consider fatty acids the building blocks of the fat in foods and the fat found on our bodies. The basic categories are Saturated (let’s call them sat fats), Monounsaturated (mono), and Polyunsaturated (poly). For example, Canola oil on average has only 7 % sat, 32% poly, and 61% mono fats, while coconut oil is 91% sat, 2% poly and only 7% mono fat. The fats in animal products (pork, beef, and dairy) are rich in saturated fatty acids (68% for dairy and 40-50% for pork & beef). A nice bar chart that gives a comparison of the most common dietary fats can be found at http://www.canola.org/PDF/dietarychart.pdf#zoom=100 .

Only trace amounts of trans fatty acids are found in naturally in foods, such as in dairy products. Most of the trans fats we eat are man made, through a chemical process whereby plant oils are “partially hydrogenated”. This process alters the chemical bonds of mono or poly fats to make these fats more solid in consistency and less likely to go rancid, but it also forms trans fatty acids.

How much is too much saturated fat?

Most of the health guidelines from the government (2005 USDA Food Guide, see http://www.mypyramid.gov/guidelines/index.html ) and private organizations, such as the American Heart Association (http://www.americanheart.org ), advocate that we restrict our intake of saturated fats to not more than 10% of daily caloric intake. For those at risk for heart disease or with heart disease, the level goes down to 7% of calories. For example, an inactive 40 year old man weighing 180 lbs. needs about 2000 calories a day to maintain his current weight, so it would be recommended that he not exceed 22 g of saturated fat per day or if he has a high blood cholesterol, not more than 15 grams daily. (To estimate your calorie need multiply your weight in pounds by 10 for women and 11 for men. Keep in mind that fats have 9 calories per gram.) The average American gets most of their saturated fat (25.5 grams/day on average) from these foods: 13.1% Cheese;11.7% Beef and other meats; 7.8% Milk; 4.9% Oils; 4.7% Ice cream/frozen dairy desserts; 4.7% Cakes/cookies/quick breads/doughnuts; 4.6% Butter. Most people can easily lower sat fat intake by choosing skim or 1% milk, less cheese and/or lower fat cheeses, and very lean meats and poultry. However eating habits vary, if you are at risk for heart disease, it’s worth the time and money to get a careful eating habits assessment by a registered dietitian to help you identify and limit hidden sources of saturated fat.

Are there goals or limits for trans fat?
Nutrition authorities recommend that we eliminate (completely) trans fat from our diets.  Where do we get most of our trans fat?  The average American eats 5.8 grams a day.  The larger dietary sources on average are: 40%  Baked goods, cakes, cookies, crackers, pies, breads, muffins; 21%  Animal products (including fried animal foods); 17%  Margarine (stick); 13%  French fries, chips, popcorn.  The good news is that in January 2006, it will be mandatory to include trans fat on the Nutrition Facts panel on the food label.  The grams of trans will appear just under the saturated fat content of the food.  Any amount less than 0.5 grams of trans per serving can be labeled as 0 grams of trans by law, so you will find foods with partially hydrogenated oils on the ingredient list labeled as “no trans”.   The new labeling law has food manufacturers scrambling to change their product recipes, so every week there are newly reformulated products on the shelf!   See the table below for gram amounts in commonly eaten foods, but keep in mind these numbers will change. There is now a “trans free” shortening on the grocery store shelf, a product which typically has a very large amount of trans fats. Soon there will be “trans free” French fries and donuts and cookies, and the bad news is that they will still be high calorie, high saturated fat, and nutrient poor foods that should be enjoyed only occasionally, with a healthy dose of moderation.