The human body needs dietary fat, and all fats, including saturated fatty acids, play important roles in the body (1).
There are certain fatty acids, however, that we must consume in the foods that we eat each day because the body cannot produce these fats and they play critical structural and functional roles.
For example, the body cannot produce omega 3’s like alpha-linolenic acid because we do not possess the enzyme required to produce this compound which is important for brain development and function (2). Dietary sources of alpha-linolenic acid include kale, spinach, soybeans, walnuts, chia seeds, hemp seeds, and flaxseeds.
The human body is also unable to produce omega 6’s like linoleic acid, a structural part of cell membranes and necessary for maintaining cell membrane fluidity, and it is involved in cell signaling (3). A deficiency of linoleic acid can result in delayed growth in children, scaly skin lesions, and a low platelet count (3). Dietary sources of linoleic acid include nuts, seeds, eggs, and meat.
Consuming healthy fats each day, in the foods we choose to eat, is important to body structure and function. Healthy fats help our body to absorb fat-soluble nutrients like vitamins A, D, E, and K, and they provide building blocks for substances like hormones.
Main dietary fats in our food
Here are a few dietary fats and functions they serve in the body.
Saturated fats are solid at room temperature due to their single bond structure between carbon molecules. Dietary saturated fats provide important building blocks and energy stores for the body (4). Short-chain saturated fatty acids like acetic, propionic, and butyric acids are absorbed quickly and transformed into glucose to provide energy for the body (5). Additionally, some short-chain fatty acids like butyric acid support the production and replication of colon cells, they stimulate the absorption of certain nutrients like sodium and chloride and the production of the mucus lining, and they reduce problematic bacteria in the gut (5).
Foods that contain saturated fats include meat, dairy, and cheese from animals, and tropical oils like coconut or palm oil.
Monounsaturated fats are liquid at room temperature due to their double bond structure. A few types of monounsaturated fats (MUFAs) include oleic acid, palmitoleic acid, and vaccenic acid (5). Some MUFAs like oleic acid can increase the HDL (“good”) to LDL (“bad”) cholesterol ratio which leads to a decreased risk for blood clot formation and reduced risk for stroke and heart disease (5). MUFAs also have a positive influence on cell membrane structure which can improve insulin resistance and decrease the risk for conditions like type 2 diabetes (6).
Foods that contain monounsaturated fats include nuts and seeds like macadamia, almonds, pecans, cashews, and sunflower and pumpkin seeds. Oils like olive and peanut oil are also high in MUFAs, and avocados are a good source of this fat as well.
Polyunsaturated fats are also liquid at room temperature because these molecules contain two or more double bonds. Polyunsaturated fats (PUFAs) include those “essential” fatty acids like omega 3s and omega 6s that the body cannot produce (5). PUFAs can help reduce LDL (“bad”) cholesterol, triglycerides, blood pressure, and slow plaque buildup in the arteries which can lower the risk for stroke and heart disease (7).
Foods that contain polyunsaturated fats include fatty fish like salmon and sardines, plant-based oils like safflower and flaxseed oil, and nuts like walnuts.
How much dietary fat do we need?
Fats, no matter which type, contain about nine calories in every gram. That makes dietary fat more energy-dense than carbohydrates and protein, which each provide about 4 calories per gram.
The daily need for dietary fat will be different for each person. The right amount of fat to eat will depend upon your calorie and personal biological requirements or needs.
Although we each have varying dietary fat needs, everyone should consume those “essential” fats that the body cannot produce but needs for proper structure and function each day.