Of these, the unsaturated fats are the healthy fats while the other two are categorized as unhealthy.
Unsaturated fats are again sub-classified as monounsaturated and polyunsaturated. The difference between the two is that the former contains only one double bond in its chemical structure while the latter contains two or more double bonds in its structure.
What are polyunsaturated fats? Definition
Polyunsaturated fats (PUFA short for polyunsaturated fatty acid) along with monounsaturated fats (MUFAs) are the healthy fats, unlike saturated and trans fats. They are considered healthy because of their health benefits on the body such as reducing the bad cholesterol and the risk of heart disease and stroke.
You should substitute the saturated fat and trans fat in your diet with these healthy fats. They are found mostly in nuts, seeds, fish, seed oils, and oysters.
Polyunsaturated fats include essential fatty acids omega-3 and omega-6 fats. Our body does not make these fatty acids. You, therefore have to provide your body with these through selected foods containing these healthy fats incorporated in your diet.
Chemically, the constituent hydrocarbon chain possesses two or more carbon bonds–carbon double bonds.
Oils that contain polyunsaturated fat are liquid at room temperature but become solid when chilled. Olive oil is an example.
When consumed in moderation, polyunsaturated fats are heart-healthy. They help to lower the bad cholesterol (LDL) and triglycerides, thereby reducing the risk of heart disease and stroke. The LDL cholesterol can clog your arteries and interfere with blood supply.
Besides, these healthy fats also provide nutrition to the body cells, which helps in their growth and function.
Oils rich in polyunsaturated fats also provide vitamin E, which is a much-needed antioxidant.
These fats help to lower the blood pressure in hypertensive people and the elevated blood sugar in diabetics.
In healthy people, they reduce the risk of developing hypertension and diabetes.
Foods sources of polyunsaturated fats
Plant-based oils like soybean oil, corn oil, and sunflower oil are high in polyunsaturated fat content.
Other sources include certain nuts and seeds such as walnuts and sunflower seeds, tofu and soybeans. These foods contain alpha-linolenic acid (ALA), a type of omega-3 fatty acid.
Fish, such as salmon, mackerel, herring, albacore tuna, and trout are another good source of these healthy fats. Eating fish two or three times a week is an excellent way to get omega-3 fats.
Higher blood content of omega-3 fatty acids is linked to a lower risk of premature death among senior adults.
Why moderation? Calorie content
All fats contain 9 calories per gram – more than twice the amount provided by proteins and carbohydrates. Polyunsaturated fats also provide the same amount of calories per gram.
That is why you should stick to moderation when consuming fats, whether saturated or unsaturated. Eating too much fat whether healthy or unhealthy can lead to weight gain.
How much of polyunsaturated fats should you consume?
Your total fat consumption should not be more than 25% to 30% of your daily calorie intake in adult men or women. That is about 44 grams to 77 grams of total fat per day if you eat a diet of 2,000 calories a day.
The 2015 Dietary Guidelines for Americans recommends getting no more than 10% of your total daily calories from saturated fat.
The American Heart Association recommends restricting your saturated fat intake to less than 6 percent of your total daily calorie intake – that is about 120 calories or about 13 grams per day in a 2,000-calorie daily diet.
The American Heart Association further suggests that 8-10 percent of your daily calorie intake should come from polyunsaturated fats. This significantly lowers the risk of heart disease.
You should not add healthy fat foods to an already saturated fatty diet. Instead, replace the saturated fatty foods with foods that contain healthy unsaturated fats.