Polyunsaturated Fat Health Benefits

Polyunsaturated fats are dietary fats found in certain fish, nuts, seeds, and vegetable oils. A healthy fat, polyunsaturated fats can help reduce LDL cholesterol levels and lower your heart disease and stroke risk. 

In addition to heart health, some polyunsaturated fats have been shown to promote brain health, improve mental-health conditions such as depression, prevent Alzheimer's disease. They may even aid in weight loss.

Like all fat, polyunsaturated fat is calorie-dense, with nine calories per gram, compared with four calories per gram of carbohydrate or protein. If you count calories or watch your weight, be mindful not to overindulge.

Saturated vs. Unsaturated Fats

There are two main types of dietary fat: saturated fat and unsaturated fat. Unsaturated fats include monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs). Their chemical structure distinguishes one from the other.

Saturated Fat

Saturated fats have no double carbon bonds in their molecular structure and are "saturated" with hydrogen atoms. These are fats that are solid at room temperature, such as butter and lard. High intake of saturated fat has been linked to high LDL cholesterol levels and heart disease.

Unsaturated Fat

Unsaturated fats, on the other hand, have double carbon bonds. Those double bonds make unsaturated fat bendable, which is why they remain liquid, even in the refrigerator.

Monounsaturated fats have one double carbon bond, while polyunsaturated fats have multiple double bonds. According to the American Heart Association, swapping out saturated fat for monounsaturated or polyunsaturated fat can reduce LDL cholesterol levels and improve heart health.

Different Types of Polyunsaturated Fat

Polyunsaturated fats take on different forms, but the two most notable are the essential fatty acids omega-3 and omega-6. They are necessary because the body cannot manufacture them, so they must be taken in through diet.

Omega-3

Omega-3 fatty acids are found in oily fish (such as salmon and trout), nuts, and seeds. Omega-3 fatty acids are generally favored among health experts because of the benefits that they may provide to the body.

Omega-3s have a structural role in cells and are found in exceptionally high amounts in the brain, sperm, and retina. In a different form called eicosanoid, it is responsible for functions in the cardiovascular, cardio, immune, and endocrine systems. Finally, this nutrient is vital in infant health and development.

Other foods high in omega-3 include:

• Flaxseed
• Chia seeds
• Walnuts
• Plant-based oils (flaxseed oil, soybean oil, and canola oil)
• Cold-water fatty fish (salmon, mackerel, tuna, herring, and sardines)

Many people take omega-3 fish oil supplements to ensure they get enough of these beneficial essential fats in their diet. About 20% of the world population consumes less than 250 mg of seafood omega-3 per day. Low or very low blood levels of omega-3 have been observed worldwide, even with overall greater intakes of omega-3s in plants.

In 2019, the American Heart Association reviewed 13 studies involving a little less than 130,000 people to find that marine omega-3 supplementation reduced heart attacks, heart disease death, and total heart disease. Most studies reviewed were conducted using doses of less than 1000 mg per day.

The FDA has no set recommendation for omega-3 fatty acid intake. They suggest a total fat intake of 65 grams per day. The FDA requires that labels on dietary supplements should not recommend a daily intake of EPA and DHA higher than 2 grams per day.

The FDA recommends consuming no more than 3 grams per day of EPA and DHA combined, including up to 2 grams per day from dietary supplements.

Omega-6

Omega-6 fatty acids are found in some plant-based foods, including nuts, seeds, and vegetable oils, such as soybean, cottonseed, corn, sunflower, and safflower oil.

While still considered healthier than saturated fat, research suggests that too much omega-6 compared to omega-3 may lead to inflammatory diseases, including cardiovascular disease, diabetes, obesity, and rheumatoid arthritis.

Foods high in omega-6 include:

• Corn oil
• Safflower oil
• Sunflower seeds or sunflower oil
• Pumpkin seeds
• Pine nuts
• Pistachios
• Other plant-based oils (including grapeseed, soy, peanut, and vegetable)
• Mayonnaise
• Some salad dressings

What's more, the amount of omega-6 fat that we tend to consume has increased dramatically in recent decades, while, in general, the amount of omega-3 fat we consume is lower. Your balance of omega-3 fatty acids to omega-6 fatty acids should be 1:2 or 1:1.

Health Benefits

In addition to essential fatty acids, polyunsaturated fats are rich in vitamin E, a vital antioxidant with many health benefits. Replacing saturated dietary fats with polyunsaturated fats can help reduce LDL-cholesterol levels, which in turn can lower your risk for heart disease.

There has also been research suggesting that foods high in omega-3 fatty acids may reduce your risk for certain cancers, including breast cancer and colorectal cancer. However, a large clinical trial found that consumption of omega-3 supplements did not provide these protective benefits.

The National Institutes of Health notes that research results related to omega-3s and cancer have been inconsistent and vary by cancer site and other factors, including gender and genetic risk.

Consumption of omega-3 is also associated with a reduced risk of developing age-related macular degeneration, dry eye disease, rheumatoid arthritis, Alzheimer’s disease, dementia, and other conditions. Research is ongoing to confirm these benefits and determine if supplements can provide the same benefits as eating omega-3 foods.

Polyunsaturated Fats in Your Diet

While health experts aren't certain about the extent of the benefits they provide, most recommend replacing saturated fat with healthier polyunsaturated fat.

Polyunsaturated Oils

Cooking with polyunsaturated oils can be a healthy way to add flavor to your food. For example, you can sauté vegetables in vegetable oil instead of butter.

However, keep in mind that plant-based polyunsaturated fats have a lower flashpoint, meaning they burn at a lower temperature. So you'll have to watch your food when you cook it and cook it at a lower temperature.

You can replace one-third to one-half of the butter in baked goods with a vegetable oil such as canola oil when baking. And, of course, you can use polyunsaturated oils in salad dressings.

While most vegetable oils are healthy, they can sometimes go bad. Polyunsaturated oils turn rancid more quickly than other fats.

To prevent cooking oils from going rancid, store in a cool, dark place before opening, and refrigerate after opening. Before using an open bottle, check for rancidity by smelling and touching the oil. Don't use it if it smells metallic, bitter, or soapy or is sticky to the touch.

Fatty Fish

Fish like salmon and tuna can be a healthy addition to your diet. Not only do they boost your intake of polyunsaturated fat, but when they replace meat, they also reduce your overall intake of saturated fat.

However, not all fish dishes are created equal. Try to enjoy your fish without breading or batter, and choose healthy preparation methods such as grilling or roasting instead of frying. You should also try to limit your intake of high-mercury-containing fishes such as marlin, tuna, sea bass, king mackerel.

Nuts and Seeds

If you consume snacks throughout the day, consider replacing starchy foods such as chips and crackers with healthier nuts and seeds. Not only do these plant-based foods provide better nutrition, but they are also likely to help you to feel full longer because of the protein and fiber they provide.

Hydrogenating Polyunsaturated Fats

One downside to polyunsaturated oils is they are used to create trans fats, which raise LDL cholesterol levels and lead to heart disease and diabetes. Trans fats are made in an industrial process that adds hydrogen to vegetable oil, creating a more shelf-stable product.

Before the 1990s, trans fats were considered a healthier alternative to saturated fats. Margarine, for example, is often made of trans fats and was promoted as a heart-healthy option to butter. Since the discovery that trans fats are bad, many margarine companies have reformulated their product to eliminate trans fats.

To see if your food contains trans fats, read the nutrition labels. Trans fats are separated under the total fat heading. In ingredient lists, the term "partially hydrogenated" before an oil indicates it is trans fat.