The word “fat” immediately conjures negative thoughts for most people. In reality, fats are an inescapable, necessary and often healthy part of a balanced diet. The key is to identify the types of fats found in our foods, and to recognize that some are far better than others from a health perspective. While the body makes fat as a result of excessive calorie intake, the types of fats we are discussing are dietary fats found in plant and animal food sources. Along with protein and carbohydrates, dietary fat is one of the three macronutrients that provide energy for the body.1 Eliminating fat completely from your diet is not possible since fat supports numerous body functions – for example, some vitamins are fat-soluble and therefore require fat in order to benefit your body.2 Understanding the four basic dietary fats can aid in making healthy decisions and contributing to a balanced diet.
Saturated Fat (“bad fat”)
This type of fat comes mainly from animal sources, such as red meat and dairy products, but is also found in tropical vegetable oils such as coconut and palm.3 Saturated fat raises total blood cholesterol levels, which can increase the risk of cardiovascular disease, and it also increases the risk of type 2 diabetes.4 For this reason, saturated fat intake should be limited to low levels. Limit saturated fats by eating mostly lean, white meats; avoiding deep-fried foods; using liquid oils such as olive and canola instead of solid fats such butter, shortening or lard; and limiting the amount of full-fat dairy products such as cream, rich sauces and high-fat cheeses.
Trans Fat (“bad fat”)
While some trans fats are naturally occurring in small quantities in certain animal food sources, the majority of trans fats we see in food products today are a result of the partial hydrogenation of unsaturated fats. This process, in short, turns an unsaturated, liquid fat into a fat that is semisolid at room temperature. While this type of fat is desirable for its shelf stability and cooking capabilities, the risk is that the molecular adjustment of the fat has been shown to convey negative health effects when consumed. There has been much debate and federal regulation over trans fats in recent years, and the bottom line is that these fats should be consumed at minimum levels, if at all. Trans fats are found most commonly in fried foods, candy, snacks, vegetable shortening and many commercial
baked goods.
Monounsaturated Fat (“good fat”)
This fat can be considered your best friend in the world of fats. Monounsaturated fats are naturally occurring in a variety of foods such as olive oil, nuts, nut oils, canola oil and avocados. Research has shown that these fats help improve “good” cholesterol levels and maintain blood sugar control, which may assist in disease prevention and control.5 Therefore, when looking to make positive changes in your diet, you are better off replacing saturated and trans fats with monounsaturated fats, rather than eliminating fats altogether.
Polyunsaturated Fat (“good fat”)
This type of fat is found predominately in fatty fish, plant-based oils and foods such as soymilk, tofu and sunflower, sesame and pumpkin seeds.6 Like its monounsaturated cousin, polyunsaturated fat helps to decrease the risk of heart disease by improving cholesterol levels. In addition, a specific type of polyunsaturated fat – Omega-3 fatty acids – has been noted as a particularly heart-healthy fat. Found mostly in certain fish, flax and walnuts, Omega-3s are known to reduce the risk of coronary artery disease while contributing to overall heart health.7
It is worth noting that no fat sources are purely saturated or unsaturated; instead, most are combinations of fat types. As with everything, moderation is the best advice, and it is important to be educated on the specific fat composition of different foods in the case of special dietary needs. Ongoing research suggests that high quantities of saturated and trans fats contribute to a variety of health issues including obesity, cardiovascular disease, type 2 diabetes and cancer, so it is best to limit (or eliminate, in the case of trans fats) them. It is recommended that total fat intake be limited to 20%–35% of calories (of which saturated fats should be less than 10% and trans fats not more than 1%).8
References:
1,2,4,5,7 Dietary Fats: Know which Types to Choose. 2011. Retrieved from: http://www.mayoclinic.com/health/fat/NU00262 [October 19, 2011].
3,6,8Smith, M.; Paul, M.; Segal, R. (2011). Choosing Healthy Fats. Retrieved from: http://www.helpguide.org/life/healthy_diet_fats.htm [October 19, 2011].
Resources:
The Nutrition Source: Fats and Cholesterol. 2011. Retrieved from Harvard School of Public Health: http://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-full-story/index.html [October 19, 2011].