Saturated fat and trans fat are the two types of fat that raise LDL (“bad”) cholesterol, but they do it differently and to different degrees. Trans fat is the worst offender because it raises LDL while simultaneously lowering HDL (“good”) cholesterol, a double hit that no other dietary fat delivers. Saturated fat raises LDL but generally leaves HDL intact or even increases it slightly.
How Saturated Fat Raises LDL
Your liver has receptors that pull LDL cholesterol out of your bloodstream. Saturated fat suppresses the activity of those receptors, so LDL particles stay circulating longer and accumulate to higher levels. The more saturated fat you eat, the less efficiently your liver clears LDL from your blood.
This makes saturated fat the single biggest dietary driver of high LDL. In a randomized crossover study comparing the effects of dietary cholesterol (from eggs) and saturated fat, researchers found that saturated fat intake was significantly correlated with LDL levels, while dietary cholesterol was not. In other words, the cholesterol you eat matters far less than the saturated fat you eat when it comes to your blood cholesterol numbers.
The American Heart Association recommends keeping saturated fat below 6% of your total daily calories. On a 2,000-calorie diet, that works out to roughly 13 grams per day. Common sources include butter, red meat, full-fat dairy, and tropical oils like palm oil.
Why Trans Fat Is the Worst
Trans fat raises LDL cholesterol and lowers HDL cholesterol at the same time. That combination significantly increases the risk of heart attack and stroke, which is why the FDA pulled partially hydrogenated oils (the main source of artificial trans fat) from the food supply in 2018.
Trans fat hasn’t disappeared entirely, though. Small amounts occur naturally in beef, lamb, and dairy products. Refined vegetable oils can also contain trace amounts as a byproduct of processing. These levels are low enough that they don’t pose the same risk as the industrial trans fats that used to be packed into margarine, baked goods, and fried foods. But if you see “partially hydrogenated oil” on an ingredient list of an imported or older product, that’s a red flag.
Not All Saturated Fats Act the Same
Saturated fat isn’t a single molecule. It’s a family of fatty acids, and some are worse for cholesterol than others. Palmitic acid, the most common saturated fat in the Western diet (found heavily in palm oil, meat, and dairy), is the primary culprit behind LDL increases. Stearic acid, another saturated fat found in cocoa butter and beef tallow, actually lowers LDL when it replaces palmitic acid in the diet. It also lowers HDL slightly, but its net effect on heart risk appears more neutral.
This distinction explains some of the confusion around foods like dark chocolate. Cocoa butter is high in stearic acid, so its saturated fat doesn’t raise LDL the way an equal amount of butter (high in palmitic acid) would.
The Coconut Oil Question
Coconut oil is roughly 82% saturated fat, which sounds alarming. But in a randomized trial published in BMJ Open, coconut oil did not significantly raise LDL compared to olive oil. It also raised HDL more than both olive oil and butter. Butter, by contrast, significantly worsened the ratio of total cholesterol to HDL compared to coconut oil.
That said, coconut oil isn’t a health food in the way olive oil is. It just appears to behave better than its saturated fat content would predict, likely because its dominant fatty acid (lauric acid) is metabolized differently than palmitic acid. If you use coconut oil occasionally in cooking, it’s not the same risk as loading up on butter, but swapping it for olive oil or another unsaturated oil is still a better move for your cholesterol.
Why Cheese and Butter Aren’t Equal
This is one of the more surprising findings in cholesterol research: cheese and butter can contain the same amount of saturated fat, yet cheese consistently raises LDL less. In one randomized trial, participants who got 13% of their daily calories from butter saw significant increases in total and LDL cholesterol. Those who ate cheese with an identical fat content did not see the same rise. Across multiple studies, cheese induced 5.7% lower total cholesterol and 6.9% lower LDL cholesterol compared to butter with the same saturated fat load.
Researchers attribute this to what’s called the food matrix effect. In cheese, fat is bound up with calcium, protein, and the structure of the milk fat globule membrane, which appears to change how that fat is absorbed and metabolized. The practical takeaway: not all high-fat dairy is equally bad for cholesterol. Cheese appears to be a meaningfully better choice than butter, even at the same fat content.
What to Replace Bad Fats With
Simply cutting saturated fat isn’t enough if you replace it with refined carbohydrates or sugar, which can raise triglycerides and lower HDL. The benefit comes specifically from replacing saturated fat with unsaturated fat, particularly polyunsaturated fat from sources like walnuts, flaxseed, fatty fish, and liquid vegetable oils like soybean and sunflower oil.
A 2017 American Heart Association presidential advisory reviewed the core randomized trials on this swap and found that replacing saturated fat with polyunsaturated fat reduced cardiovascular disease events by approximately 29 to 30%. That’s comparable to the benefit seen with statin medications. The effect was consistent across multiple large trials with at least two years of follow-up and verified adherence.
Monounsaturated fats, found in olive oil, avocados, and most nuts, also improve your cholesterol profile, though the evidence base for cardiovascular risk reduction is strongest for polyunsaturated fats. A practical approach: cook with olive or canola oil instead of butter, snack on nuts instead of cheese crackers, and choose fish over red meat a few times per week. These swaps target the mechanism directly, restoring your liver’s ability to clear LDL from the bloodstream.