Unsaturated fats are the healthiest type of fat. They come in two forms, monounsaturated and polyunsaturated, and both lower harmful LDL cholesterol, reduce inflammation, stabilize heart rhythms, and cut the risk of heart disease when they replace saturated fat or refined carbohydrates in your diet. Neither form is clearly superior to the other: a large meta-analysis found no significant difference in LDL or HDL cholesterol levels when diets high in monounsaturated fat were compared head-to-head with diets high in polyunsaturated fat. The best approach is eating plenty of both.
Monounsaturated Fats
Monounsaturated fats are liquid at room temperature and found in olive oil, avocados, most nuts, and canola oil. Replacing a carbohydrate-heavy diet with one rich in monounsaturated fat lowers blood pressure, improves cholesterol ratios, and reduces overall cardiovascular risk. These fats also help prevent insulin resistance, a precursor to type 2 diabetes.
Extra-virgin olive oil deserves special mention. It has the lowest oxidation rate of any common cooking oil, meaning it produces fewer cell-damaging free radicals than other options. For everyday cooking like baking, oven roasting, or stir-frying, light or refined olive oil handles the heat well. Save extra-virgin olive oil for dressings, dips, or finishing dishes where you can taste its flavor.
Polyunsaturated Fats and Omega-3s
Polyunsaturated fats include two essential fatty acids your body cannot make on its own: omega-3 and omega-6. Both are necessary, but the balance between them matters. The American Heart Association recommends that 8 to 10 percent of your daily calories come from polyunsaturated fat, and evidence suggests that going up to 15 percent (in place of saturated fat) can further lower heart disease risk.
Omega-3 fatty acids, specifically EPA and DHA, play roles that go well beyond heart health. They maintain the integrity of brain cell membranes, support communication between neurons, and reduce neuroinflammation. A pooled analysis of 14 randomized trials covering nearly 27,000 adults found that omega-3 supplementation produced a small but statistically significant improvement in cognitive test scores. Interestingly, higher doses didn’t necessarily produce better results, suggesting the benefit kicks in once you reach a minimum effective level rather than increasing in a straight line with dose.
The best whole-food sources of omega-3s are fatty fish like salmon, mackerel, sardines, and trout. A 3.5-ounce serving of cooked wild salmon provides about 8 grams of total fat, much of it omega-3. Farmed salmon is even fattier at around 12 grams per serving. Plant sources like walnuts, flaxseeds, and chia seeds provide a shorter-chain omega-3 (ALA) that your body converts to EPA and DHA only in small amounts, so fish or algae-based sources remain the most efficient way to get these fats.
Why the Omega-6 to Omega-3 Ratio Matters
Omega-6 fats aren’t harmful in moderate amounts, but modern diets tend to be flooded with them. Seed oils like soybean, corn, and sunflower oil are packed with omega-6, and they show up in processed foods, restaurant fryers, and packaged snacks. When the ratio of omega-6 to omega-3 climbs too high, it promotes low-grade inflammation, oxidative stress, and damage to blood vessel walls.
Research in animal models shows that atherosclerosis severity increases as the omega-6 to omega-3 ratio rises, with the least arterial plaque forming at a 1:1 ratio. In human trials, reducing the ratio from roughly 18:1 down to about 3:1 lowered the release of inflammatory markers for hours after a high-fat meal. You don’t need to obsess over exact numbers. The practical fix is straightforward: eat more fatty fish, walnuts, and flaxseeds while cutting back on processed foods made with seed oils.
Where Saturated Fat Fits In
Saturated fat raises LDL cholesterol, and the longstanding advice to limit it still holds. But the source matters more than researchers once thought. A 2024 USDA systematic review found moderate evidence that replacing processed meat and red meat with dairy is associated with lower cardiovascular disease risk. The evidence on dairy fat specifically is mixed: some reviews show low-fat dairy lowers risk, while others find similar outcomes between full-fat and low-fat dairy. The strongest and most consistent finding is that processed meat (bacon, sausage, deli meats) carries the highest cardiovascular risk among saturated fat sources.
One critical nuance: swapping saturated fat for refined carbohydrates like white bread, sugary cereals, or sweetened drinks does not improve heart health. That trade lowers LDL cholesterol but also drops protective HDL cholesterol and raises triglycerides, producing a net effect on the heart that’s roughly as bad as eating the saturated fat. The benefit comes specifically from replacing saturated fat with unsaturated fat or whole, unprocessed carbohydrates.
Choosing Cooking Oils
Different oils suit different heat levels. Avocado oil has one of the highest smoke points of any cooking fat, making it ideal for searing, browning, and deep frying. Refined or “light” olive oil also handles high heat well and works for baking and stir-frying. Extra-virgin olive oil is best used without heat, in dressings, dips, or drizzled over finished dishes, where its antioxidants and flavor stay intact.
Flaxseed oil is rich in omega-3s but breaks down quickly with heat. Use it only in cold applications like salad dressings or smoothies. Coconut oil, despite its popularity, is roughly 82 percent saturated fat and doesn’t offer the cardiovascular benefits of olive or avocado oil.
Simple Ways to Shift Your Fat Intake
- Cook with olive or avocado oil instead of butter or vegetable shortening for most meals.
- Eat fatty fish twice a week. Salmon, sardines, and mackerel deliver omega-3s in a form your body uses efficiently.
- Snack on nuts. A small handful of walnuts, almonds, or pistachios provides monounsaturated and polyunsaturated fats along with fiber and protein.
- Cut back on processed foods. Packaged snacks, fried fast food, and shelf-stable baked goods are typically made with seed oils high in omega-6 and often contain trans fats.
- Replace red and processed meat with plant proteins or fish. Substitution analyses from large cohort studies consistently link this swap to lower coronary heart disease risk, with the strongest benefit coming from cutting processed meat.
The overall pattern matters more than any single food. A diet where most of your fat comes from fish, nuts, seeds, avocados, and olive oil, while keeping processed meat and refined carbohydrates low, is the most consistently supported approach for long-term cardiovascular and brain health.