By Sheryl Wood
Updated nutritional guidelines recommend consuming 20 to 30 percent of your daily calories from fats. But the type of fat you eat can have a big impact on your health.
Fats are essential for proper cell function and different systems of the body. Some fats are manufactured by the body, but those that are not must be consumed in the diet. Not all fats are the same, and knowing which are good for you and which could damage your health can guide your food choices.
The updated recommendations from the Academy of Nutrition and Dietetics advise people to increase their consumption of a particular type of fat — polyunsaturated fats (PUFAs) called omega-3 PUFAs — and to limit the amount of trans fat and saturated fats they eat.
The Academy of Nutrition and Dietetics and the Dietitians of Canada recently released updated guidelines for dietary fat consumption. These guidelines suggest which types of fats to include in a healthy diet and which ones to avoid. The position paper was authored by registered dietitian nutritionists Gretchen Vannice, MS, RDN, nutrition consultant, Santa Cruz, CA, and Heather Rasmussen, PhD, RD, assistant professor at Rush University Medical Center.
Dietary fat exists mainly in the form of triglycerides and are usually classified by whether the fat molecule is saturated with hydrogen or not. Fats classified this way are referred to as fatty acids that are polyunsaturated, monounsaturated, saturated or trans fats.
Polyunsaturated fatty acids are important because they are needed as fuel for human cells, and they must come from the diet. There are several different classifications of PUFAs — omega-3 PUFAs and omega-6 PUFAs being two of them. Each has a different function in the body. For example, omega-3 PUFAs can cause blood vessels to open, and omega-6 PUFAs can cause them to constrict.
The new guidelines advise increasing consumption of omega-3 fatty acids. This can be done by including fatty fish and other seafood, chia seeds, walnuts and flax seeds in the diet. Omega-3 fatty acids are also found in canola and soybean oil.
Monounsaturated fatty acids (MUFAs) are found in macadamia nuts, olive oil, canola oil, beef tallow, lard and avocados. Currently, MUFAs are the most highly consumed fat in the U.S. diet and represent 36 percent of the total fat consumed.
Monounsaturated fatty acids are healthier than saturated or trans fats, but they are not as beneficial to health as PUFAs. The recommended consumption of MUFAs is between 15 and 20 percent of a person's total daily calories.
Saturated fatty acids (SFAs) are found in animal products — including eggs, butter and meat. They are also found in coconut oil, palm oil and cocoa butter. The scientific evidence of the health effects of saturated fatty acids is mixed, with some studies showing harm and some showing benefit.
The current average intake of SFAs is 11 percent of daily calories. The new nutritional guidelines recommend that seven to 10 percent of daily calories come from saturated fats.
The nutritionaists who authored the paper state that, “Replacing SFA with PUFA instead of refined carbohydrate appears to be beneficial. Decreasing SFA without caloric replacement is an effective strategy for reducing total energy content (calories) of the diet and promoting healthy body weight.”
Trans fatty acids (TFAs) are found in red meat and milk fats. Trans fats are present as partially hydrogenated vegetable oil and are often found in commercially made pastries such as cookies. Because of scientific evidence showing that TFAs have a role in increasing coronary heart disease, the nutritional guidelines suggest that the consumption of TFAs be kept as low as possible.
The updated position of the Academy of Nutrition and Dietetics regarding consumption of fatty acids can be summarized as follows:
- Fats in the diet should be limited to between 20 and 30 percent of total daily calories.
- The type of fat you eat is important because there are good fats and bad fats.
- Dietary fat should be made up mostly of PUFAs and MUFAs.
- Because of its health benefits, omega-3 fatty acid consumption should be increased by eating more fish, nuts and seeds.
- Since both omega-3 and omega-6 fatty acids are required for good health, the new guidance does not recommend eliminating all fats from the diet.
- Consumption of trans fats and saturated fats should be limited or avoided.
The position paper was published in the January issue of the Journal of the Academy of Nutrition and Dietetics.