The general consensus between dietitians, nutritionists, and other experts is that saturated fat is less healthful than unsaturated fat. However, the overall health impact of saturated fat remains controversial. Some researchers believe it may increase the risk of heart disease, while others believe moderate amounts might benefit overall health.

According to findings from a 2015 analysis, reducing saturated fat intake may produce a “small but potentially important” decrease in the risk for heart disease. The authors suggest that people reduce their intake of saturated fats and replace some of them with unsaturated fats.

Fat is an essential nutrient that the body needs to function fully. Fats in the diet help the body absorb vitamins and minerals and serve other vital roles. Fat stored in body tissues is critical for:

  • energy storage and metabolism
  • body temperature regulation
  • insulation of the vital organs

However, a diet with too much fat can increase body weight along with a person’s risk of cardiovascular disease.

The most recent Dietary Guidelines for Americans recommend that adults get between 20–35% of their daily calories from fats. However, saturated fats should account for no more than 5–6% of a person’s daily calorie intake.

In this article, we look at the differences between saturated and unsaturated fat, the roles they play in the body, and which foods provide them.

a woman looking at milk in at supermarket and wondering which contain saturated or unsaturated fats Share on Pinterest
A person can opt for low fat milk as part of a heart-healthy diet.

Researchers have studied the health effects of saturated and unsaturated fats for decades.

A 2017 scientific review reported an association between people who have heart disease or a risk of heart problems and those who consume higher amounts of saturated fats in their diet.

The researchers reported that saturated fats may increase levels of low-density lipoprotein or LDL, or “bad” cholesterol. Elevated LDL cholesterol in the blood may increase a person’s risk of heart disease.

The study authors also reported that replacing saturated fat with unsaturated fat may also bring down the risk of cardiovascular disease (CVD).

However, recent research has challenged the link between saturated fats and heart disease. A 2019 review did not record any significant effects of reducing saturated fat on people’s risk of heart disease. Trans fats, however, did increase the risk.

The jury is still out on saturated fat. While a diet containing too many saturated fats can increase body weight and the risk of CVD, it might not be as harmful as scientists once thought.

In contrast, the health benefits of unsaturated fats are well-established. The first evidence of their “heart-healthful” properties dates back to the 1960s. Researchers found that people from Greece and other Mediterranean regions had a low rate of heart disease compared to other locations despite consuming a relatively high-fat diet.

Unsaturated fats help lower a person’s levels of LDL cholesterol, reduce inflammation, and build stronger cell membranes in the body. They may also help a person reduce the risk of rheumatoid arthritis, according to a 2014 study.

Nutrition experts classify fats into three main groups: Saturated, unsaturated, and trans fats.

Saturated fat

These fats have single bonds between their molecules and are “saturated” with hydrogen molecules. They tend to be solid at room temperature.

Food sources that contain high levels of saturated fat include meat and dairy products, such as:

  • cheese
  • butter
  • ice-cream
  • high-fat cuts of meat
  • coconut oil
  • palm oil

A 2015 meta-analysis found that medium-chain triglycerides (MCTs) might be the most healthful type of saturated fat. Coconut, for example, provides plenty of MCTs.

Unsaturated fat

Unsaturated fats contain one or more double or triple bonds between the molecules. These fats are liquid at room temperature in oil form. They also occur in solid foods.

This group breaks down further into two categories, called monounsaturated fats and polyunsaturated fats.

Dietary sources of unsaturated fats include:

  • avocados and avocado oil
  • olives and olive oil
  • peanut butter and peanut oil
  • vegetable oils, such as sunflower, corn, or canola
  • fatty fish, such as salmon and mackerel
  • nuts and seeds, such as almonds, peanuts, cashews, and sesame seeds

Mediterranean diets are typically high fat but have links to good heart health. Learn more about this diet here.

Trans fat

These fats take a liquid form that converts to solid fats during food processing techniques.

Some meats and dairy products contain small amounts of trans fats, but they play a role in processed foods.

However, since 2015, the Food and Drug Administration (FDA) has taken steps to eliminate partially hydrogenated oils (PHOs), a significant source of trans fats, from processed food. Manufacturers had until the beginning of 2020 to stop adding PHOs to their food products.

Examples of food products that may still contain trans fats include cookies, crackers, doughnuts, and fried foods. However, trans fats are becoming less and less present.

Most fatty foods contain a combination of fatty acids. As such, many foods do not contain just saturated or unsaturated fats, which can make it difficult for a person to eliminate only one type.

Most health organizations and dietary experts recommend eating saturated fats in moderation and replacing them with unsaturated fats when possible.

The American Heart Association (AHA) strongly recommend a saturated fat intake of no more than 5–6% of total daily calories. This means that for an average 2000-calorie daily diet, people should consume no more than 120 calories or 13 grams (g) from saturated fats.

Some research from 2014 and 2018 supported a higher intake of MCT saturated fats, such as from coconut oil. However, a comprehensive 2020 analysis found that coconut oil intake produces higher LDL levels than vegetable oils.

People with existing heart problems should speak to a doctor before adding new saturated fats to their diet.

Some easy ways for people to balance their dietary intake of fats include:

  • Choosing low fat milk instead of whole milk, or lean meat instead of fatty cuts of meat.
  • Being cautious about foods that claim to be fat-free or low in fat. Many of these products contain added sugars and refined carbohydrates to replace the fats. These ingredients can increase caloric intake without any extra nutritional value.
  • Limiting intake of processed foods, as these may be high in trans fats and sodium.
  • Grilling, baking, or steaming foods instead of deep-frying them.
  • Switching to healthful fats. Foods such as sardines, avocado, and walnuts provide a good amount of unsaturated fats. These may support brain development, strengthen the immune system, and improve heart health.

Despite the abundance of research on dietary fats, there are still questions regarding the relationship between saturated fats and adverse health outcomes, such as heart disease.

However, many experts agree that limiting the intake of most saturated fats and consuming enough unsaturated fats, such as plant oils, avocado, and fish, is the ideal approach to a healthful diet in the long-term.

Dietary changes can have unexpected effects on health, especially for people with underlying health conditions and heart problems.

Q:

Is butter more healthful than margarine?

A:

Since this has been written about extensively, I will borrow from a reliable source, Harvard Medical School.

“Today, the butter vs. margarine issue is really a false one. From the standpoint of heart disease, butter remains on the list of foods to use sparingly mostly because it is high in saturated fat. Margarines, though, aren’t so easy to classify. The older stick margarines turned out to be worse for a person’s health than butter. Some of the newer margarines that are low in saturated fat, high in unsaturated fat, and free of trans fats are fine as long as you don’t use too much (as they are still rich in calories).
Healthier alternatives to butter or margarine include olive oil and other vegetable oil-based spreads, which contain beneficial mono and polyunsaturated fats.”

So, the big picture is that neither is great, and many experts would recommend oils rather than butter or margarine.

However, if it is just a butter vs. margarine comparison, then some of the current forms of margarine are better than butter. However, many people may still think that butter is better because they remember the warnings about old types of margarine having a high trans fat content.

Grant Tinsley, Ph.D. Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.