Which fatty acids should be avoided? A Complete Dietary Guide

December 7, 2025 •

5 min read

According to the World Health Organization, over 278,000 deaths annually are linked to the consumption of industrially produced trans fats. This highlights why it is crucial to know which fatty acids should be avoided for better health and well-being.

Quick Summary

This guide explains the most harmful fatty acids—trans fats and excessive saturated fats. It details their negative health impacts, lists common food sources, and provides actionable tips for healthier dietary substitutions.

Key Points

Avoid Artificial Trans Fats: Industrially produced trans fats offer no health benefits and significantly increase the risk of heart disease and stroke by raising bad cholesterol and lowering good cholesterol.
Limit Saturated Fats: High consumption of saturated fats, found in fatty meats and full-fat dairy, can raise LDL cholesterol and contribute to heart disease, though they are less harmful than trans fats.
Read Food Labels Carefully: Always check for 'partially hydrogenated oils' on the ingredients list, as some products can contain trans fats even if labeled as '0g Trans Fat'.
Replace Bad Fats with Good Ones: Substitute sources of trans and saturated fats with foods containing healthy mono- and polyunsaturated fats, such as olive oil, avocados, nuts, seeds, and fatty fish.
Choose Whole Foods Over Processed: Processed foods are a major source of hidden trans fats and high levels of saturated fats, making whole, unprocessed foods a safer and healthier choice.
Prioritize Overall Dietary Pattern: Focus on a balanced eating pattern rich in fruits, vegetables, and lean proteins, rather than fixating on a single nutrient.

The Foundation of Dietary Fats

Fatty acids are the building blocks of fats, which are an essential part of a healthy diet, providing energy and supporting critical bodily functions. However, not all fats are created equal. They are broadly categorized into saturated, monounsaturated, and polyunsaturated, with the distinction determining their impact on health. Trans fats, particularly the artificial kind, are widely considered the most damaging type and should be eliminated from the diet as much as possible. Saturated fats, while a natural part of many foods, should be limited due to their potential to raise LDL ('bad') cholesterol. By understanding the different types and their effects, you can make informed choices to protect your heart and overall health.

The Harmful Effects of Trans Fats

Trans fats, also known as trans-fatty acids, are a byproduct of a process called hydrogenation, where liquid vegetable oils are turned into solid fats. They can be found in two forms: industrial and naturally occurring. While a small amount of natural trans fat is found in the meat and dairy of ruminant animals, it is the artificial, industrially produced version that poses the most significant health risk.

How Trans Fats Damage Your Health

Raises LDL ('Bad') Cholesterol: Artificial trans fats increase low-density lipoprotein (LDL) cholesterol, contributing to the buildup of plaque in arteries.
Lowers HDL ('Good') Cholesterol: Unlike other fats, trans fats suppress high-density lipoprotein (HDL) cholesterol, which is responsible for carrying excess cholesterol away from the arteries.
Promotes Inflammation: Trans fats are linked to chronic inflammation, which is a key factor in the development of heart disease, stroke, and diabetes.
No Known Nutritional Benefit: The World Health Organization and other health bodies have confirmed that trans fats offer no health benefits and that there is no safe level of consumption.

Where to Find Trans Fats

Even though many countries have restricted or banned artificial trans fats, it is still crucial to check food labels carefully. Common sources include:

Baked goods (cookies, cakes, pastries)
Fried foods (doughnuts, fried fast food)
Margarine and vegetable shortening
Processed snack foods (crackers, microwave popcorn)

The Complex Role of Saturated Fats

Saturated fatty acids are typically solid at room temperature and are found naturally in many animal-based and some plant-based products. Historically, they have been considered a major dietary culprit for heart disease due to their effect on blood cholesterol.

The Debate Around Saturated Fat

The consensus is that while saturated fats are not as detrimental as trans fats, excessive consumption can still be problematic. They increase LDL cholesterol, which can heighten the risk of cardiovascular disease. However, recent research has nuanced this understanding, suggesting that replacing saturated fats with polyunsaturated fats is more beneficial for heart health than simply replacing them with refined carbohydrates.

Common Sources of Saturated Fat

Foods to limit due to their high saturated fat content include:

Fatty cuts of red meat, pork, and lamb
Poultry skin and processed meats like sausage and bacon
Full-fat dairy products (butter, cheese, cream, whole milk)
Tropical oils (coconut oil, palm oil, cocoa butter)
Many fast foods and pre-packaged baked goods

Reading Nutrition Labels for a Healthier Diet

To effectively avoid unhealthy fatty acids, learning how to read a nutrition label is essential. The U.S. Food and Drug Administration (FDA) has specific guidelines to help consumers identify fat content.

Check 'Total Fat': This section lists the total amount of fat per serving, but it's important to dig deeper.
Look for 'Saturated Fat' and 'Trans Fat': These are listed separately. Aim for 0g of trans fat. For saturated fat, dietary guidelines recommend keeping intake below 10% of total daily calories, and the American Heart Association suggests aiming for under 6% for a heart-healthy diet.
Read the Ingredients List: The FDA allows foods with less than 0.5 grams of trans fat per serving to be labeled as '0g Trans Fat'. Always check the ingredient list for 'partially hydrogenated oil' to be sure.
Compare Products: Use the nutrition facts to compare similar products and choose the one with the lowest amount of saturated and trans fat.

Comparison of Harmful vs. Healthy Fatty Acids


Feature	Trans Fats	Saturated Fats	Monounsaturated Fats	Polyunsaturated Fats
Health Impact	Highly detrimental, raises LDL, lowers HDL, promotes inflammation	Detrimental in excess, raises LDL cholesterol	Beneficial, lowers LDL cholesterol, good for heart	Beneficial, lowers LDL cholesterol, essential for body function
Common Sources	Processed foods, fried foods, baked goods with partially hydrogenated oils	Fatty meat, full-fat dairy, tropical oils	Olive oil, avocado, almonds, peanuts, canola oil	Fatty fish, walnuts, sunflower oil, corn oil, flax seeds
State at Room Temperature	Solid	Solid	Liquid	Liquid
Dietary Recommendation	Avoid entirely, banned in many regions	Limit intake to under 10% of total calories	Choose frequently as a healthier alternative	Choose frequently as a healthier alternative

Making Healthier Dietary Substitutions

To minimize your intake of harmful fatty acids, focus on replacing them with healthier alternatives. This simple switch can have a profound impact on your cardiovascular health and overall well-being.

Swap Butter for Olive Oil: Use olive oil for sautéing vegetables or as a bread dip instead of butter.
Choose Lean Meats and Fish: Replace fatty cuts of beef or pork with lean poultry or fish like salmon and tuna, which are rich in beneficial omega-3 fatty acids.
Snack on Nuts and Seeds: Instead of processed snacks like crackers or cookies, opt for a handful of almonds, walnuts, or sunflower seeds.
Use Avocado Instead of Mayo: For sandwiches and dressings, a mashed avocado offers a creamy texture with a healthy dose of monounsaturated fats.

Conclusion

While completely avoiding all sources of unhealthy fats may be challenging, understanding which fatty acids should be avoided—primarily artificial trans fats and excessive saturated fats—is the first step toward a healthier diet. By becoming a savvy label reader and making simple, intentional food swaps, you can significantly reduce your risk of cardiovascular disease and other chronic conditions. The key is not to fear all fat but to prioritize beneficial unsaturated fats while limiting or eliminating the most harmful ones. Always consult a healthcare professional or registered dietitian for personalized advice tailored to your specific health needs. For further reading on dietary recommendations, consider exploring resources from the American Heart Association.

Frequently Asked Questions

Saturated fats are solid at room temperature and have been linked to higher LDL cholesterol, while unsaturated fats are typically liquid at room temperature and, when consumed in moderation, can help lower LDL cholesterol.

No. While industrially produced trans fats (partially hydrogenated oils) should be avoided entirely, small amounts of naturally occurring trans fats can be found in the meat and dairy products of ruminant animals and are not considered as harmful.

To identify artificial trans fats, you should check the ingredients list for 'partially hydrogenated oil.' The '0g Trans Fat' label can be misleading, as products with less than 0.5 grams per serving can be listed as zero.

No, you do not need to eliminate all saturated fats. The goal is to limit your intake to less than 10% of your total daily calories and replace high-saturated-fat foods with healthier alternatives like those containing unsaturated fats.

For a healthier alternative, you can substitute butter with olive oil or canola oil for cooking. For spreads, mashed avocado is a great option.

LDL cholesterol is known as 'bad' cholesterol because it can build up in artery walls. HDL cholesterol is 'good' because it helps remove excess cholesterol from the body. Trans fats raise LDL and lower HDL, while healthy fats can have the opposite effect.

Coconut and palm oils are high in saturated fat and should be consumed in moderation as part of a balanced dietary pattern. While they are plant-based, they contain more saturated fat than other liquid vegetable oils like olive or canola oil.

The best approach is to focus on your overall diet. Prioritize whole, unprocessed foods like fruits, vegetables, lean proteins, and whole grains, and choose healthier oils like olive oil over solid fats and processed options.