Fat plays a vital role in the diet. It is one of three main nutrients the body requires, along with carbohydrates and protein. Fat provides energy and helps the body absorb certain vitamins from foods.  According to the Dietary Guidelines for Americans, 2020-2025, no more than 20 to 35 percent of daily calories should come from fat to stay within the Acceptable Macronutrient Distribution Range (U.S. Department of Agriculture [USDA] and U.S. Department of Health and Human Services [HHS], 2020). All calories come from one of four possible sources: fat, carbohydrate, protein, and alcohol. At 9 calories per gram, fat provides more calories per gram than the other three. Scientific research has proven that the types of fats need to be considered.

Historically, as scientists learned about fats, low-fat and fat-free diets were popular, but this is contrary to what is now known about the role of fat in the body. It is now understood that the type of fat eaten from various food sources has more of an impact on health; that is, the difference in health effects between “good,” beneficial fats and “bad,” harmful fats (Harvard T.H. Chan School of Public Health 2019). Rather than reducing overall fat intake to a low-fat diet, one should instead focus on choosing more of the beneficial unsaturated fats and limiting the harmful saturated fat.

Saturated Fat

Saturated fat is an unhealthy dietary fat because it has been linked to heart disease and other health problems. Too much saturated fat in the diet raises LDL cholesterol, which can lead to a buildup of cholesterol in arteries, increasing the risk for heart disease and stroke (American Heart Association, n.d.). It is most often solid at room temperature and found in higher amounts in animal products, tropical oils, and fully hydrogenated oils.

Fully hydrogenated oils (FHOs) are created from vegetable oils that have been chemically modified to make them a solid fat. The process, called hydrogenation, adds hydrogen and changes the oil from an unsaturated fat to a saturated fat. Food products with FHOs are more shelf stable; however, in excess, this type of fat is detrimental to the health of the consumer (Center for Food Safety and Applied Nutrition [CFSAN] 2018a).

Food Sources
Fully hydrogenated oils; fatty beef, lamb, pork; poultry with skin; lard, shortening, and margarine; whole or reduced-fat (2 percent) milk and other dairy products made from whole or reduced-fat (2 percent) milk including cream, butter, and cheese; tropical plant-based oils, such as palm oil, palm kernel oil, and coconut oil; highly processed foods, including potato chips, snack foods, bakery products, crackers, and pie crusts; fried foods; and greasy foods like pizza are all sources of saturated fat.

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Daily Intake
Per the Dietary Guidelines for Americans, 2020-2025, intake of saturated fat should be limited to less than 10 percent of total daily calories. To further reduce the risk of heart disease, the American Heart Association (n.d.) recommends limiting saturated fats to 5 to 6 percent of total daily calories. Based on a 2,000-calorie diet, that is:

• 44 to 78 grams of total fat
• 11 to 22 grams (5 to 10 percent) of saturated fat

Dietary Changes

• Replace saturated fat with unsaturated fats, particularly polyunsaturated fat, to reduce LDL cholesterol levels and cardiovascular disease risk (USDA and HHS 2020). These good fats lower the “bad” LDL cholesterol and improve the ratio of total cholesterol to “good” HDL cholesterol, lowering the risk of heart disease. Be mindful to keep total daily fat intake within the recommended limits of 20 to 35 percent of calories when replacing saturated fats with unsaturated fats.
• Include plenty of fruits, vegetables, whole grains, low-fat dairy products, nuts, seeds, and beans in your diet. These foods are naturally low in saturated fat.
• Replace red meat with skinless poultry or fish a few days each week. Instead of consuming fried meat, poultry, and fish, choose those that have been grilled, baked, roasted, or broiled. Opt for a few meatless meals each week.
• In baking, substitute applesauce, prune puree, or pureed beans for the fat. Substitute half or all the fat but note the texture of the baked product will be different. Consider experimenting with different ratios of substitutions.
• Read nutrition labels to determine how much and what kind of fats are in food products.  Also, look for added ingredients in lower-fat products. Food manufacturers often add sugar and sodium when reducing fat in products.

Other things to know about hydrogenated oils

Trans fats, found in human-made, partially hydrogenated oils (PHOs), are known to increase the risk of heart disease by increasing LDL cholesterol and decreasing HDL cholesterol levels; therefore, the goal is to consume as little trans fat as possible (CFSAN 2018a). As a result, food manufacturers are no longer permitted to add PHOs to food, preventing thousands of heart attacks and deaths each year (CFSAN 2018b). While there are some naturally occurring trans fats, though very minimal in the diet, PHOs had been the main source of trans fats in the diet for many years.

Since FHOs are saturated fats and do not supply trans fats like PHOs do, their use is permitted; however, they are harmful to heart health in excess.  While making the switch from PHOs to FHOs is safer, limiting saturated fats and instead choosing unsaturated fats is still the best option.

The Heart-Healthy Fats

There are two types of heart-healthy fats: monounsaturated fats and polyunsaturated fats. These two unsaturated fats can improve cholesterol, decrease inflammation, stabilize heart rhythms, and play a role in other body functions. Unsaturated fats are liquid at room temperature and primarily found in plant foods, including nuts, seeds, avocados, olives, and oils (Harvard T.H. Chan School of Public Health 2018). Fish are also a source of unsaturated fats. Most foods contain a combination of different types of fats.

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Even though the unsaturated fats are heart-healthy fats, they still contain 9 calories per gram, so serving sizes of healthy fats must be considered to stay within the daily recommended intake and not exceed daily calorie needs.

Monounsaturated Fat

Monounsaturated fats can lower the risk of heart disease and stroke by reducing LDL cholesterol levels. It is recommended that, while still staying within the recommended intake range, more mono- and polyunsaturated fats are consumed in place of saturated fats (U.S. National Library of Medicine 2020a).

Food Sources
Monounsaturated fat sources include non-tropical plant-based oils, such as olive, canola, peanut, safflower, and sesame oils, as well as avocados, nuts, and seeds. These oils are usually liquid at room temperature but will start to solidify in cooler, refrigerated temperatures.

Dietary Changes

• Eat nuts instead of cookies or chips for a snack. Be aware of portion size, as nuts are high in calories. The recommended serving size of nuts is 1 ounce. For example, an ounce of almonds is about 23 almonds.
• Use canola or olive oil instead of butter and other solid fats. Refer to the figure below for oils high in monounsaturated fat.
• To substitute a heart-healthier oil for shortening or butter in recipes, use the following conversion:

Polyunsaturated Fat

Polyunsaturated fats can help reduce LDL cholesterol levels, which in turn can lower the risk for heart disease and stroke.  They provide important nutrients that allow the body to run efficiently and properly.  Oils rich in polyunsaturated fats also contribute vitamin E to the diet which acts as an antioxidant, helps with blood flow, and repairs body tissues.

Polyunsaturated fats include omega-3 and omega-6 fats. These essential fatty acids are needed for brain function and cell growth.  The body does not make essential fatty acids, so they can only come from food or supplements.  Omega-3 fatty acids are good for the heart by reducing triglycerides, regulating heart rhythm, slowing the buildup of plaque in arteries, and slightly lowering blood pressure. Omega-6 fatty acids help control blood sugar, reduce the risk of diabetes, and lower blood pressure (U.S. National Library of Medicine 2020b).

Food Sources
Vegetable oils, such as safflower, corn, soybean, and sunflower oils; nuts, seeds, tofu, and soybeans; and fish, including salmon, mackerel, herring, albacore tuna, and trout. are good sources of polyunsaturated fats, as is canola oil, though it is higher in monounsaturated fat

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Dietary changes

• Eat fish at least twice a week in place of red meat.
• Incorporate nuts and seeds in meals and snacks.
• Use oils high in polyunsaturated fats instead of butter or margarine. See the figure below for a breakdown of oils high in polyunsaturated fats.

*Coconut, palm kernel, and palm oil are called oils because they come from plants. However, they are solid or semi-solid at room temperature due to their high content of short-chain saturated fatty acids. They are considered solid fats for nutritional purposes.
**Shortening may be made from partially hydrogenated vegetable oil, which contains trans fatty acids.

Zesty Mixed Nuts Recipe

8 servings | serving size: ¼ cup

Prep time: 10 minutes
Cook time: 20 minutes

Ingredients

• Non-stick cooking spray
• ½ cup walnuts
• ¼ cup pepitas (pumpkin seeds), unsalted
• ¼ cup sunflower kernels, unsalted
• ½ cup cashews, unsalted
• ½ cup almonds (whole or slivered), unsalted
• 2 Tablespoons maple syrup
• ¼ teaspoon cayenne pepper
• ¼ teaspoon ground ginger

Directions

When preparing this recipe, start with clean countertops and utensils. Wash hands with soap and water. Preheat oven to 325°F. Cover a rimmed baking pan with parchment paper and spray with a small amount of non-stick cooking spray.  Mix the walnuts, pepitas, sunflower kernels, cashews, and almonds in a medium bowl.  Add the maple syrup, cayenne, and ginger, tossing with the mixed nuts and seeds to combine. Transfer the coated nuts and seeds to the prepared baking pan and spread evenly in a single layer. Bake, stirring once, until lightly toasted, about 15 – 20 minutes. Remove from the oven and cool.

Nutrient Information

Per ¼ cup serving: 210 calories, 17g total fat, 2g saturated fat, 0mg cholesterol, 0mg sodium, 10g carbohydrates, 3g added sugars, 3g dietary fiber, 6g protein

Recipe adapted from Giant Food Recipe Center: zesty mixed nuts

References

American Heart Association. (n.d.). “Saturated Fat.” Retrieved July 16, 2021.

Center for Food Safety and Applied Nutrition. 2018a. “Trans Fat.” U.S. Food and Drug Administration.

Center for Food Safety and Applied Nutrition. 2018b. “Final Determination Regarding Partially Hydrogenated Oils.” U.S. Food and Drug Administration.

Harvard T.H. Chan School of Public Health. 2018. “Types of Fat.” The Nutrition Source.

Harvard T.H. Chan School of Public Health. 2019. “Fats and Cholesterol.” The Nutrition Source.

U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2015-2020.

U.S. Department of Agriculture and U.S. Department of Health and Human Services. 2020. . (9th edition).

U.S. National Library of Medicine. 2020a. “Facts about monounsaturated fats.” MedlinePlus.

U.S. National Library of Medicine. 2020b. “Facts about polyunsaturated fats.” MedlinePlus.