Lots of incorrect information and half-truths circulate around fats. It is a nutrition topic that engenders lots of wrong information. This is partially due to the multifaceted aspect of fats: many different types of fats exist. One of the common half-truths is that fats are understood as unequivocally unhealthful, but because many types of fats are found in foods, this statement is false. Some fats are essential nutrients to a healthy body, and they provide important health benefits. But, this does not mean all types of fats are essential. Some fats can be harmful when eaten in excess so knowing the difference between fat types is important. In fact, failing to acknowledge the fact that fats come in different varieties and have different impacts on health is the root of much of the wrong information floating around.
Basic Facts on Fats from the 2015-2020 Dietary Guidelines for Americans from the USDA:
Most natural fats found in plants and animals are a combination of two sub-components: unsaturated and saturated fats. The difference between the two has to do with the number of double bonds they have in fatty acid tails. Unsaturated fats can be either monounsaturated, one double bond in the fatty acid tail, or polyunsaturated fats, more than one double bond. Unsaturated fats are, broadly speaking, healthier than saturated fats. Unsaturated fats are those typically found in seafood, vegetable oils, nuts, and seeds. Unsaturated fats are those that are liquid at room temperature, such as vegetable oils. Saturated fats, in contrast, are solid at room temperature and are commonly found in animal foods, such as red meat and dairy products, as well as prepackaged pastries, desserts, and pastries. While trans fats occur naturally in certain foods, such as ruminant (animal) fats, many are manufactured though hydrogenation, such as partially hydrogenated vegetable oils, which have been demonstrated to increase risk of disease and are no longer recognized as safe (5). Artificial trans fats are no longer allowed to be added in packaged products.
Examples of beneficial and essential fats: Monounsaturated and polyunsaturated fats are healthier than saturated and trans fats and are an important part of a balanced and healthful diet. Omega-3 and omega-6 fatty acids are types of polyunsaturated fats that are essential, meaning people must obtain these fats from their diet, and they provide many important health benefits (5).
Examples of sources of monounsaturated fats include sunflower, olive, canola, peanut, safflower, avocado and hazelnut oils; avocado, peanut butter, and most nuts; and chicken, pork, beef, and wild game (6).
Examples of sources of polyunsaturated fats include sunflower, corn, soybean, and cottonseed oils; walnuts and pine nuts; sesame, sunflower, pumpkin, and flax seeds; and seafood including salmon, trout, herring, tuna, and mackerel, all of which are excellent sources of the essential omega-3 fatty acids, EPA and DHA (6).
Benefits of Fats:
Here are some health benefits of mono and polyunsaturated fats: EPA and DHA specifically play an important role in normal growth and development in children, particularly brain development (1), may help with mood regulation and preventing depression (2), and may help decrease total body inflammation possibly preventing certain diseases (3). These unsaturated fats have been associated with positive health outcomes and reduced incidence of certain diseases. They also help make you feel full and satisfied, so you do not consume too many calories in one day, thus keeping you from eating again and again in rapid succession. Additionally, these types of fats allow your body to absorb fat-soluble vitamins A, D, E, and K, which are important for vision, bone health, immune function, and blood clotting (4).
Examples of nonessential, less-healthful fats: saturated fats are considered less healthful, and health experts recommend they be limited to no more than 10% of daily calories for adults (5). Many foods contain naturally occurring saturated fats, such as butter, red meat, and full-fat dairy; however, the main sources of saturated fat in the American diet are actually packaged foods such as sandwiches, desserts, and sweet snacks (5). Trans fats are a type of fat that are no longer recognized as safe and are not allowed to be added into packaged foods (5). Traditionally, margarine and similar butter substitutes were made from what are called partially hydrogenated oils (PHOs), which contained trans fats. However, now that PHOs are no longer allowed to be added into packaged foods, these products no longer contain trans fats.
Examples of sources of saturated fats include coconut, palm, and palm kernel oils; butter and beef fats; pork and chicken fats, and prepackaged foods such as sandwiches, cakes, cookies, doughnuts, and pastries (6)(5).
The prevailing advice is to eat foods with no (zero) trans fats and lower amounts of saturated fats relative to the two unsaturated fats. Fortunately, mono- and polyunsaturated fats are abundant in a vast variety of foods, so with mindfulness and education you should find these good fats easy to consume in higher quantities relative to saturated and trans fats.
All of the above is the skinny on fats!
References
- U.S. Food and Drug Administration and U.S. Environmental Protection Agency. Advice About Eating Fish. Advice about Eating Fish. FDA [Internet] FDA; 2021 [cited 2022 Jan 20];FDA.gov/fishadvice; EPA.gov/fishadvice. Available from: https://www.fda.gov/food/consumers/advice-about-eating-fish
- Bae J-H, Kim G. Systematic review and meta-analysis of omega-3-fatty acids in elderly patients with depression. Nutrition Research 2018;50:1–9.
- Omega-3 Fatty Acids: An Essential Contribution | The Nutrition Source | Harvard T.H. Chan School of Public Health [Internet]. [cited 2022 Jan 20]. Available from: https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/omega-3-fats/
- Reddy P, Jialal I. Biochemistry, Fat Soluble Vitamins. StatPearls. [Internet] Treasure Island (FL): StatPearls Publishing; 2022 [cited 2022 Jan 21]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK534869/
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. :164.
- U.S. Department of Agriculture. FoodData Central [Internet]. [cited 2022 Jan 25]. Available from: https://fdc.nal.usda.gov/index.html