Researchers compared two types of healthy fats to see which one is better for your heart health. They looked at 53 different studies involving 1,690 people and measured how each type of fat affected cholesterol and triglycerides in the blood. The study found that polyunsaturated fats (found in foods like fish, seeds, and vegetable oils) were slightly better at lowering cholesterol and triglycerides than monounsaturated fats (found in olive oil and nuts). However, the difference was small, and both types of healthy fats are good choices for your heart.

The Quick Take

  • What they studied: Which type of healthy fat works better for lowering cholesterol and triglycerides: polyunsaturated fats or monounsaturated fats?
  • Who participated: 1,690 adults across 53 different research studies. The studies looked at people eating diets high in either polyunsaturated fats (like fish oil and sunflower oil) or monounsaturated fats (like olive oil and avocados).
  • Key finding: Polyunsaturated fats lowered total cholesterol by about 5.7 mg/dL more than monounsaturated fats, and lowered triglycerides by about 6.6 mg/dL more. These are small but measurable differences that could matter for heart health.
  • What it means for you: If you’re trying to improve your cholesterol levels, polyunsaturated fats may have a slight edge over monounsaturated fats. However, both are healthy choices, and the most important thing is replacing saturated fats (like butter) with either type of unsaturated fat.

The Research Details

This is a meta-analysis, which means researchers looked at 53 different studies that had already been completed and combined all their results together. Each of the original studies was a randomized controlled trial, which is the gold standard in research. In these trials, some people were assigned to eat a diet high in polyunsaturated fats (getting at least 10% of their daily calories from these fats), while others ate a diet high in monounsaturated fats (getting at least 15% of their daily calories from these fats). The researchers then measured the participants’ blood cholesterol and triglyceride levels before and after the diet changes.

The researchers searched two major scientific databases (PubMed and Web of Science) through February 2025 to find all relevant studies. They looked at four main blood measurements: total cholesterol, LDL cholesterol (the ‘bad’ cholesterol), HDL cholesterol (the ‘good’ cholesterol), and triglycerides (another type of fat in the blood). By combining results from all 53 studies, they could see patterns that might not be obvious in any single study.

Combining results from many studies gives us a much clearer picture than looking at just one study. This approach is especially useful when individual studies show slightly different results. By pooling data from 1,690 people across 53 studies, the researchers could detect small but real differences between the two types of healthy fats. This meta-analysis approach also allowed them to look at whether certain factors (like whether the fat came from oils versus nuts) changed the results.

The researchers used a standard tool called the Cochrane Risk of Bias tool to check the quality of each study they included. They found that most studies had some concerns about their design, which is common in nutrition research. The fact that they combined many studies helps reduce the impact of any single study’s weaknesses. The large total sample size (1,690 people) makes the results more reliable than a single small study would be.

What the Results Show

When people ate diets high in polyunsaturated fats compared to diets high in monounsaturated fats, their total cholesterol dropped by about 5.7 mg/dL more. Their LDL cholesterol (the harmful type) dropped by about 3.3 mg/dL more, and their triglycerides (another heart risk factor) dropped by about 6.6 mg/dL more. Interestingly, HDL cholesterol (the protective type) was slightly lower with polyunsaturated fats, dropping about 0.77 mg/dL more than with monounsaturated fats.

To put these numbers in perspective, these are small changes. A typical cholesterol reading might be 200 mg/dL, so a 5.7 mg/dL difference is less than 3%. However, even small improvements in cholesterol can add up to meaningful improvements in heart health over time.

The researchers also discovered that the benefits of polyunsaturated fats became more noticeable when people ate higher amounts of total fat. For every 1% increase in calories from fat, the advantage of polyunsaturated fats over monounsaturated fats grew by about 0.5 mg/dL for total cholesterol and LDL cholesterol.

When the researchers looked at where the fats came from, they found that oils (like fish oil and vegetable oils) worked better than nuts or whole food sources for lowering LDL cholesterol and triglycerides.

The analysis revealed that the type of food source matters. When polyunsaturated fats came from oils rather than nuts or other whole foods, they were more effective at lowering LDL cholesterol and triglycerides. This suggests that the form in which you consume these fats might influence how much they help your cholesterol levels. The researchers also found that the overall amount of fat in the diet influenced how much benefit people got from switching to polyunsaturated fats.

Previous research has shown that both polyunsaturated and monounsaturated fats are better for your heart than saturated fats. This new analysis adds important detail by directly comparing these two healthy fats. The findings suggest that while both are beneficial, polyunsaturated fats have a slight advantage for cholesterol management. This aligns with some previous studies but provides stronger evidence by combining results from many trials.

The researchers noted several important limitations. First, most of the original studies had some quality concerns, though none were serious enough to exclude them. Second, nutrition studies are challenging because people don’t always follow diets perfectly, and it’s hard to control everything people eat. Third, the studies varied in how long they lasted and how strictly people followed the diets, which could affect the results. Finally, the differences found were small, so while they’re statistically significant (meaning they’re unlikely to be due to chance), their real-world importance for individual people is modest.

The Bottom Line

If you’re trying to improve your cholesterol levels, focus on replacing saturated fats (like butter, fatty meats, and full-fat dairy) with unsaturated fats. Both polyunsaturated fats (fish, seeds, vegetable oils) and monounsaturated fats (olive oil, avocados, nuts) are good choices. Based on this research, polyunsaturated fats may have a slight edge for cholesterol management, but the difference is small. The most important thing is making the switch from saturated to unsaturated fats, rather than worrying too much about which type of unsaturated fat you choose. Confidence level: Moderate - the evidence is solid, but the differences are small.

This research is most relevant for people concerned about their cholesterol levels or those at risk for heart disease. It’s also useful for people following heart-healthy diets who want to know which healthy fats might work best. However, this research doesn’t apply to people with certain medical conditions (like some genetic disorders affecting fat metabolism) who should follow their doctor’s specific recommendations. People with nut allergies or those who dislike fish should know that monounsaturated fats from other sources are still a healthy choice.

Changes in blood cholesterol typically take 2-4 weeks to appear when you change your diet, though some people see changes within 1-2 weeks. The full benefit usually develops over 4-8 weeks. Keep in mind that genetics play a big role in cholesterol levels, so not everyone will see the same amount of improvement.

Want to Apply This Research?

  • Track your daily intake of polyunsaturated and monounsaturated fats separately for 4 weeks. Log sources like fish servings, nuts, seeds, olive oil, and vegetable oils. Aim to get at least 10% of your daily calories from polyunsaturated fats and 15% from monounsaturated fats.
  • Replace one saturated fat source each week with a polyunsaturated or monounsaturated fat source. For example: swap butter for olive oil, replace fatty beef with salmon, or add a handful of almonds as a snack. Track which swaps you make and how you feel.
  • If you have access to blood tests, check your cholesterol levels every 6-8 weeks while making these dietary changes. Use the app to track your fat intake patterns and correlate them with any cholesterol improvements. Note which specific foods and oils you’re using, since the research suggests oils may be more effective than whole food sources.

This research provides general information about how different types of healthy fats affect cholesterol levels in groups of people. Individual responses to dietary changes vary significantly based on genetics, overall diet, exercise, and other health factors. If you have high cholesterol, heart disease, or are taking cholesterol-lowering medications, consult your doctor or registered dietitian before making major dietary changes. This information should not replace personalized medical advice from your healthcare provider. The small differences found in this study may not be clinically significant for every individual.