Dietary fat is made up of a combination of saturated, monounsaturated, and polyunsaturated fats. Dietary fat provides energy (calories) and essential fatty acids. Each gram of fat supplies 9 calories, making fat the most calorically dense nutrient.
The current recommendation by the Institute of Medicine (IOM) is that 20-35% of your total calories should come from dietary fat. However, too much dietary fat, particularly saturated fat and trans fat, can increase the risk of cardiovascular disease. Let’s look at each type of dietary fat.
Saturated fats can cause increased LDL-cholesterol (known as “bad cholesterol”) in your blood, which contributes to heart disease. Studies have shown that for every 1% increase in calories from saturated fat, there is approximately a 2% increase in LDL-cholesterol. Foods high in saturated fat include fatty meats (such as bacon, sausage, and luncheon meats) and regular-fat dairy products such as cheese, ice cream, and whole milk.
Trans-fats raise LDL-cholesterol levels, similar to saturated fat, and increase risk of heart disease. Trans-fats are the result of adding hydrogen to unsaturated fat. The major source of trans fats is partially hydrogenated vegetable oils, which are used in many manufactured foods such as cookies, crackers, margarine, and snack chips.
Polyunsaturated fats lower LDL-cholesterol and HDL-cholesterol (known as “good cholesterol”). Two essential fatty acids – omega-3 (linolenic) & omega-6 (linoleic acid) fatty acids – are polyunsaturated fats. Omega-3 fatty acids can help to protect against heart disease by improving your arteries and blood lipids.
- Omega-3 fatty acids are found in cold water fish (herring, mackerel, salmon, sardines, swordfish, and tuna) and flaxseed oil. The American Heart Association recommends the consumption of fish high in omega-3 fatty acids at least twice a week.
- Omega-6 fatty acids are found in many vegetable oils (e.g., corn, safflower, soybean, cottonseed, and sunflower oils), nuts, and seeds.
Monounsaturated fats can lower LDL-cholesterol and other blood fats (triglycerides) without lowering HDL-cholesterol. So these fats are considered to be the most beneficial fats! Good sources of monounsaturated fats include olive oil, canola oil, avocados, pecans, and peanuts. Epidemiologic evidence, confirmed by clinical research, shows that diets rich in MUFA have a lower incidence of Coronary Heart Disease.
Dietary cholesterol can also raise LDL-cholesterol in your blood. Dietary cholesterol is only found in foods derived from animals. The highest levels of cholesterol are found in fatty meats, organ meats, egg yolks, cheese, and cream.