More on Dietary Fat: Beyond the Jargon
Looking again at our comparison between a doughnut and an avocado that we began last month, a low-fat enthusiast might assume that the doughnut with 16 grams of fat is better than the avocado that has 22 grams of fat. However, the devil is in the details in understanding what kinds of fat promote health.
To demystify the nutrition jargon around dietary fat, let’s look at the different types of fats, what they are called and where we find them in our food. Remember, no food is 100 percent of any one fat. There is a balance of fats within each food that signals an important lesson to be learned—variety is critical to balance. In addition, dietary fat that comes from whole, unprocessed food sources are supportive of health (like the avocado) and processed fat from packaged food (like the doughnut) are linked to chronic inflammatory conditions.
What are the different kinds of dietary fat? Fat can be categorized by many different attributes: the number of double bonds (saturated/unsaturated), the location of the first double bond (omega-3/6), its length (long/short/medium chain) and whether the body can produce it or not (essential fatty acids).
There are several types of saturated fatty acids, the most popular among them are lauric, palmitic and stearic. Saturated fat provides stability and structure and assists in the repair of cells. It can be long chain (milk, red meat, dark chocolate), short chain (produced in the colon by bacteria), or medium chain (coconut) and is found in both animal and plant foods.
Unsaturated fat means that there is at least one double bond and this translates into the fat being liquid at room temperature (oil). There are two types of unsaturated fat, monounsaturated and polyunsaturated—the difference between them is the number of double bonds.
Foods that are primarily monounsaturated fat include olive, sesame, avocado, nuts and canola which are generally high in the antioxidant vitamin E and important for providing fluidity in cell structures. Polyunsaturated fats, a less stable and therefore easily oxidized fat, can be divided into omega-6 and omega-3 fats. Omega-6 fats from foods such as soy, corn, and safflower drive the inflammatory pathway while omega-3 fats from food such as walnuts, flaxseed and fatty fish drive the anti-inflammatory pathway. DHA and EPA are types of omega-3 fats. We need both omega-6 and omega-3 in our diet in order to meet the needs of the body.
Fat is such an important nutrient that your body will produce it from basic nutrients. However, there are some fats that are not produced by the body and must be consumed: linoleic acid (omega-6) and linolenic acid (omega-3). The American diet is overrun with sources of linoleic acid as it is high in industrial seed oils that companies use to prolong the shelf-life of their products. This has created an unequal ratio of omega-6 to omega-3 fats in our diet. Prior to the industrialization of our food supply, the ratio of omega-6 to 3 was close to 1:1. In the standard American diet that contains mostly processed foods, the ratio can be as high as 23:1. This ratio can be linked to the incidence of the chronic inflammatory diseases of our day affecting our cardiovascular, nervous, and immune systems and is the major reason why the kind of fat you eat makes a huge impact on your health. Too much omega-6 fats in your diet will drive the inflammatory pathway that is meant to protect you in acute situations but will cause disease when chronically activated. By increasing sources of omega-3 in your diet and decreasing sources of omega-6, the ratio will move closer to 1:1 and the inflammatory balance can be restored.
Understanding what kinds of fats are important to a healthy diet is a good first step, knowing how to use them ensure that they provide health benefits is the next step. Tune in next month for the final part to the series on how to use dietary fat to promote health.
Julie Wendt holds a M.S. in Integrative Health and Nutrition from Maryland University of Integrative Health and consults with adults and children. She can be reached at [email protected].