Fat--a dreaded word whether in reference to the fat on your body or the fat in food. Today we are going to look more into dietary fats and see if they deserve their infamous reputation or not.
Dietary fat is important for several reasons. Fat plays a role in skin and hair health, cushions our organs; makes up cell membranes; insulates the body to help maintain proper body temperature; helps with the absorption of fat-soluble Vitamins A, D, E, and K; acts as an energy source; and more. We need to get somewhere between 20-35% of our total Calories from fat, so for a 2,000 kcal diet that would translate into 400-700 kcals or somewhere between 44-77gm fat per day.
Basically the fat that that we consume comes from two types of lipids--Triglycerides and Cholesterol. For more information on the different types of cholesterol, refer to my previous post. We are going to focus on triglycerides today because they make up the majority of the dietary fat that we ingest (some sources estimate up to 90%). Triglycerides are made up of three fatty acid chains attached to a glycerol backbone in the shape of an “E”, with the fatty acids varying to form the different types of fats commonly discussed--Saturated, Trans, Mono- and Poly-Unsaturated. These are the types of fat that we are going to scrutinize.
Saturated fat is easily distinguishable because it is usually solid at room temperature. As far as structure goes, the fatty acids have no double bonds between the carbon atoms. There are many types of saturated fatty acids which have varying lengths, but what’s important to know is that this fat has been associated with heart disease and recently has been named a greater culprit than dietary cholesterol in raising blood cholesterol levels. Saturated fat is found mostly in animal products, such as meat, eggs, butter, cheese, and milk but is also in coconut and palm. The recommended intake is less than 10% of total daily Calories or less than 7% for those with heart disease, diabetes, or high LDL cholesterol. (It’s important to note that foods are a combination of different types fat, but we classify them based on their predominant type).
Trans fat is considered the worst fat, being shown to simultaneously raise LDL and lower HDL cholesterol (bad combination!). Though trans fats are naturally occurring in some animal products, the primary offender is the trans fat created through the process of partially hydrogenating oils to keep them shelf stable. In this process, unsaturated fats have some hydrogen atoms added forming a double bond with the hydrogen atoms on the same side (for you science junkies). Since these oils are added to processed foods, the main sources of trans fat include cookies, crackers, baked goods, snack foods (including those health halo granola bars), and some margarines (usually solid, stick varieties), but are also found in the frying oil used in restaurants. Due to the association with coronary heart disease and other increased health risks, the recommendation is to consume as little of this fat as possible, and while you’re at it, replace trans with mono- or poly-unsaturated fat to further reduce your health risk.
Monounsaturated fatty acids, less frequently called “Omega-9s” have one double bond with a cis-configuration, making them liquid and found primarily in vegetable oils like olive, canola, peanut, and grapeseed. They are also predominant in avocado, nuts, and seeds. These oils are associated with cardiovascular health and healthy cholesterol levels. This effect is marked when used to replace saturated or trans fat. Aim for 10-15% of your Calories from this type of fat.
Polyunsaturated fatty acids have more than one cis double bond, so they are also liquid at room temperature. This category includes the famous Omega-3 and Omega-6 fatty acids associated with positive effects on the brain, heart, cholesterol, and possibly also mood and cognitive function. You can find Omega-3 fatty acids in canola, flax, and soybean oil; walnuts; chia, hemp, and flax seeds; and oily fish like salmon, herring, and mackerel. Omega-6 fatty acids are abundant in many vegetables oils (canola, soybean, sunflower, and corn) as well as many nuts (walnuts, almonds, peanuts, etc.) and eggs. Both types of polyunsaturated fat can constitute up to 10% of total Calories, but a ratio of 4:1-1:1 of omega 6 to omega 3 has advised.
I hope that this post has helped clear up any confusion about the different types of fatty acids out there and what foods you may want to add to (or decrease in) your diet to promote your optimal health.
Michaela Ballmann, MS, RD is enthusiastic about guilt-free eating, whole person care, and nourishing food. Her main interest is in getting people to love food, their bodies, and themselves. Michaela seeks to share the truth about nutrition and help restore you to what you once were–a healthy, whole human being. Connect with her through her podcast, blog and nutrition counseling at Wholify.