March 24, 2009
The following column is written by Shirley Perryman, a registered dietitian and Extension specialist in the Department of Food Science and Human Nutrition at Colorado State University. The department is part of the College of Applied Human Sciences.
Fats contribute a large proportion of the calories in our diet so it's not surprising they get a lot of attention-especially considering the increasing problem of obesity in our country-when we think of eating right. However, along with calories, fats provide essential fatty acids and help with the body's absorption of fat soluble vitamins. Both good fats and bad fats can be found in the American diet and it can be confusing to sort them out.
Since March is National Nutrition Month, and this year's theme is "Eat Right," it's a good time to review how fats gets a bum rap and discuss how they can and should be included in a healthy diet.
Four out of five people believe that all fats are unhealthy. That's not true; some fats are healthier than others. Choose foods low in saturated fats, trans fats and cholesterol more of the time for good heart health. Saturated and trans fats raise total cholesterol and the "bad" cholesterol, called LDL. In addition, trans fats can decrease the "good" cholesterol, called HDL. Both saturated fats and trans fats increase the risk of heart disease.
- Saturated fats are solid at room temperature. Foods that fall into this category include all animal foods-meat, poultry and dairy, including butter, milk and cheese. Dietary sources of cholesterol are only found in animal products.
- Trans fats, though naturally present in meat and dairy products, are not a concern from these sources. The majority of trans fats in our food are created during a manufacturing process that converts liquid oils into solid fats. Trans fats act like saturated fats in the body with all the same negative consequences. In fact, there is no level of trans fats recommended in the dietary guidelines because they are not essential to the body.
Certainly the recommendation is not to eliminate animal foods from your diet, but rather to choose leaner options more of the time for optimal heart health.
To balance your diet with fats that are more healthy, choose monounsaturated and polyunsaturated fats more often.
Olive oil contains the greatest amount of monounsaturated fats. Other good sources of oil high in monounsaturated fats that also contain low levels of saturated fats are canola, safflower, flaxseed, sunflower, corn, soybean and peanut oil.
Polyunsaturated fats are found in fish and certain plant foods and supply both omega-3 and omega-6 fats. These polyunsaturated fats are essential and can only be supplied by food. They lower triglycerides and total cholesterol and may increase HDL, all of which lowers the risk of heart disease. There is some evidence they may also decrease the risk of hypertension, rheumatoid arthritis and even reduce the risk of depression and Alzheimer's disease.
There are three kinds of omega-3 fats: eicosapentaenoic acid or EPA, docosahexaenoic acid or DHA, and alpha-linolenic acid or ALA.
- EPA and DHA are most plentiful in fish - especially fatty fish such as salmon, trout, mackerel, sardines and tuna. The American Heart Association recommends that adults eat fish at least twice a week. Pregnant and breastfeeding women should also eat fish twice a week, but they should avoid certain fish high in mercury. These women or anyone concerned with mercury in fish should check with their physician for specific recommendations.
- ALA comes only from plant sources such as flaxseed, walnuts, canola oil, soybean oil, pumpkin seeds, tofu and dark green leafy green such as kale. ALA must first be converted to EPA and DHA for the body to use it. However, the conversion process is inefficient so you would need to eat more of these foods to reap the health benefits.
Linoleic acid, called LA, and arachidonic acid are omega-6 fatty acids. They are found in liquid vegetable oils, nuts and seeds. Eggs, dairy products and meat also contribute omega-6s. There is some evidence that omega-6s may lower HDL, the good cholesterol.
Is omega-6 a "good" or a "bad" fat? The bottom line is to include more unsaturated fats and fewer saturated fats instead of worrying about the proportion of omega-6s and omega-3s in your diet.
Translated into food, getting enough good fats in your diet means:
Check labels for the presence of trans fats and choose them as little as possible. Or better yet put them back on the shelf, which would certainly send a message back to food companies about providing more healthy choices.
Contact: Shirley Perryman
Phone: (970) 491-2404