Fatty acids are healthy fats that can be found in many different foods. Unlike saturated fats, polyunsaturated fatty acids like linoleic and linolenic acid are healthy and an important part of your diet. In fact, fatty acids like these are considered to be essential for good health and can be used for the prevention of many diseases.
Linoleic vs. Linolenic Acid
Linolenic acid and linoleic acid are similarly named omega fatty acids that have different roles in human health and nutrition. Linolenic acid most commonly refers to alpha-linolenic acid (ALA), an omega-3 fatty acid found in many nuts, vegetables and oils. Linoleic acid, on the other hand, typically refers to a type of omega-6 fatty acid commonly found in nut, seed and refined vegetable oils. Both omega-3 and omega-6 fatty acids are essential polyunsaturated fatty acids with well-established health benefits.
You should know that there are also two types of fatty acids that have linolenic acid in their names: gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DGLA). Despite their names, these types of linolenic acid are omega-6 fatty acids more similar to linoleic acid. Like linoleic acid, they can be found in nut, seed and vegetable oils.
Omega-3 and omega-6 fatty acids are both essential fats that have a lot of overlap in terms of nutritional importance. However, the human body requires them in different quantities for good health. Different cultures consume different ratios of omega-3 and omega-6 foods. Western societies, such as the United States and United Kingdom, consume many foods rich in omega-6 fatty acids — so many, in fact, that these regions are thought to consume too many omega-6 fatty acids compared to omega-3 fatty acids.
What Is Alpha-Linolenic Acid?
Alpha-linolenic acid is an essential, polyunsaturated fatty acid. ALA is the most common type of omega-3 fatty acid and the most important from a dietary perspective. ALA acts as a precursor to other omega-3 fatty acids, specifically eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, only small amounts of ALA are converted into DHA and EPA.
There are several types of omega-3 fatty acids, but ALA, DHA and EPA are considered to be the most important. You can obtain fatty acids like DHA and EPA from select foods, including fatty fish and seaweed. ALA, on the other hand, is much easier to consume as it's found in these products as well as a variety of other foods, including fruits, vegetables, nuts and seeds.
DHA and EPA have been associated with the vast majority of the health benefits associated with omega-3 fatty acids. However, the importance of ALA is becoming increasingly better understood. ALA is now believed to have a wide range of benefits, including anti-cancer, anti-inflammatory, anti-osteoporotic, anti-oxidant, cardioprotective and neuroprotective effects.
Consuming Alpha-Linolenic Acid
Many foods are rich in ALA. You can find this essential fatty acid in many plant-based foods, for example:
- Vegetables: Brussels sprouts
- Fruits: avocado
The Dietary Guidelines for Americans currently states that a total of 1.1 to 1.6 grams of ALA per day are suitable for a healthy diet. However, a 2019 study in the Proceedings of Nutrition Society Journal has shown that this value may be increased to at least 2 grams per day. If you're wondering whether you're consuming sufficient amounts of ALA, you can use resources like the USDA National Nutrient Database to identify foods rich in this and other omega-3 fatty acids.
Once you consume foods with ALA, the body processes it into other long-chain polyunsaturated omega-3 fatty acids like EPA and DHA. These three omega-3 fatty acids are the most common omega-3 fats; all of them have major roles in maintaining the functions of the nervous system and the immune system.
Importance of Omega-3 Fatty Acids
Omega-3 fatty acids have a wide range of well-established health benefits. They may help prevent a variety of different conditions, including:
Many health benefits are associated with DHA and EPA, which small amounts of ALA are converted to. Alone, ALA's benefits are primarily associated with neuroprotective effects and anti-inflammatory and anti-obesity properties. However, unlike DHA and EPA, which have been studied in various clinical trials, it's not typically utilized clinically.
Only recently has ALA been considered medically relevant — although this is primarily due to secondary effects. For instance, a 2015 study in the BioMed Research International Journal discusses how ALA can increase levels of brain-derived neurotrophic factor (BDNF), a neuroprotective protein. BDNF has been shown to act as an antidepressant and to improve outcomes following stroke.
What Is Linoleic Acid?
Linoleic acid is the most common type of omega-6 fatty acid, an essential, polyunsaturated fatty acid that comes from foods like nuts, seeds and refined vegetable oils. Omega-6 fatty acids are an important part of a healthy diet. They're particularly beneficial for your immune system and metabolism.
There are two main types of linoleic acid:
- Linoleic acid: the most common form of omega-6 fatty acid that is commonly found in nuts, seeds and vegetable oils
- Conjugated linoleic acid (CLA): a conjugated form of linoleic acid that's more commonly found in animal-source foods like meat and milk products
Linoleic acid and conjugated linoleic acid are similar, but they behave differently in the body due to their different origins and small structural differences. Linoleic acid is much easier to obtain than conjugated linoleic acid. However, conjugated linoleic acid is generally thought to have more health benefits.
Read more: Foods That Are High in CLA
Importance of Omega-6 Fatty Acids
Linoleic acid and other omega-6 fatty acids are essential for good health. Linoleic acid helps maintain the skin, nerve, immune and reproductive systems, as well as various other bodily functions. Linoleic acid acts as a precursor, converting into other long-chain polyunsaturated fatty acids, including arachidonic acid and DGLA.
Omega-6 fatty acids are associated with improved health, with fatty acids like linoleic acid, arachidonic acid and DGLA linked to the prevention of heart disease. CLA, which is found in animal products like milk and meat, has been shown to prevent diseases like diabetes, hypertension, cancer and metabolic syndromes. Although it's structurally similar to linoleic acid, CLA has a wider variety of health benefits (like cholesterol reduction) that make it clinically relevant as a nutritional supplement.
Although linoleic acid is an essential fatty acid, it should be consumed in moderation. Too much linoleic acid means that there will be too much arachidonic acid and other fatty acids converted, resulting in the overactivity of certain bodily systems. For example, omega-6 fatty acids are associated with immune system function — and too much can increase inflammation. Excess consumption of omega-6 fatty acids has also been linked to obesity.
Healthy Omega-3 and Omega-6 Ratios
A look at foods with linolenic acid and linoleic acid shows a similarity: Most of the time, these fatty acids are found in plant-based foods. Additionally, foods like nuts, seeds and vegetable oils are typically rich in both omega-3 and omega-6 fatty acids. In many cases, these foods contain more omega-6 fatty acids than omega-3 fatty acids. You should always try to select ingredients that enrich your diet with omega-3 fatty acids and minimize your consumption of omega-6 fatty acids.
While the popularity and affordability of fast food result in higher consumption of omega-6 than omega-3 fatty acids, it's long been known that a specific ratio of omega-6 to omega-3 is necessary for good health. Ideally, the ratio should be fairly small, but this can be hard if you consume a typical Western diet.
According to the journal Biomedicine and Pharmacotherapy, decreasing your ratio of omega-6 to omega-3 fatty acids can even help with health issues. Omega-6 to omega-3 in the range of 3-to-1 or 2-to-1 has been shown to help reduce inflammation in people with inflammatory diseases, while a ratio of 5-to-1 is helpful for asthmatics. In contrast, most Western diets have a ratio of 15-to-1 to 16.7-to-1, and ratios as low as 10-to-1 can have negative effects on your health.
These days, people who consume a Western diet typically consume too many omega-6 fatty acids. When you consume too many omega-6 fatty acids, you may increase your risk of certain diseases. This includes cancer, heart disease and autoimmune diseases, including conditions like inflammatory bowel disease and rheumatoid arthritis. The high quantity of omega-6 fatty acids in Western diets is one of the reasons omega-3 supplements are so popular.
Obtaining Dietary Omega-3 and Omega-6
Obtaining the correct ratios of omega-3 and omega-6 fatty acids in your diet can be challenging. You can utilize resources like the USDA National Nutrient Database to identify foods rich in linoleic acid, alpha-linolenic acid and other specific omega fatty acids. It's particularly important to look at foods like oils, which most people use on a daily basis. Oils such as flaxseed and soybean can have substantial amounts of omega-6 fatty acids, while those like walnut are much richer in omega-3 fatty acids.
You should also keep in mind that fatty acids like conjugated linoleic acid can differ between animal products. Factors that influence CLA content include whether the animal has multiple stomachs and what kind of foods it's eaten. Although ALA is primarily found in plants, it can also be found in marine food products. For instance, farmed salmon and wild salmon also have different omega-3 levels, which can impact the amount of ALA present.
- Harvard Health Publishing: Harvard Health Blog: Finding Omega-3 Fats in Fish: Farmed Versus Wild
- Meat Science: Conjugated Linoleic Acid in Meat and Meat Products
- Journal of Nutrition and Metabolism: Health Implications of High Dietary Omega-6 Polyunsaturated Fatty Acids
- Biomedicine and Pharmacotherapy: Dossier: Polyunsaturated Fatty Acids in Biology and Diseases: The Importance of the Ratio of Omega-6/Omega-3 Essential Fatty Acids
- Experimental Biology and Medicine: The Importance of the Omega-6/Omega-3 Fatty Acid Ratio in Cardiovascular Disease and Other Chronic Diseases
- Open Heart: Importance of Maintaining a Low Omega-6/Omega-3 Ratio for Reducing Inflammation
- Prostaglandins & Other Lipid Mediators: Linoleic Acid and the Pathogenesis of Obesity
- Biochimie: Linoleic Acid: Between Doubts and Certainties
- Public Health Nutrition: Association of Foods Enriched in Conjugated Linoleic Acid (CLA) and CLA Supplements With Lipid Profile in Human Studies
- European Journal of Pharmacology: Modulation of Inflammation and Immunity by Dietary Conjugated Linoleic Acid
- Obesity Research & Clinical Practice: Health Benefits of Conjugated Linoleic Acid (CLA)
- Cochrane Database of Systematic Reviews: Omega-6 Fatty Acids for the Primary Prevention of Cardiovascular Disease
- American Journal of Clinical Nutrition: Efficacy of Conjugated Linoleic Acid for Reducing Fat Mass
- BioMed Research International: Alpha-Linolenic Acid: An Omega-3 Fatty Acid With Neuroprotective Properties — Ready for Use in the Stroke Clinic?
- National Institutes of Health: Office of Dietary Supplements: Omega-3 Fatty Acids
- Inflammation: Anti-Inflammatory Potential of Alpha-Linolenic Acid Mediated Through Selective COX Inhibition: Computational and Experimental Data
- Annals of Clinical Psychiatry: Omega-3 Fatty Acids in Psychiatry
- Postgraduate Medical Journal: Omega-3 Fatty Acids: A Comprehensive Review of Their Role in Health and Disease
- Proceedings of the Nutrition Society: Dietary Fat Composition: Replacement of Saturated Fatty Acids With PUFA as a Public Health Strategy, With an Emphasis on α-Linolenic Acid
- SelfNutritionData: Nutrition Facts and Calories
- USDA: Food Composition Databases
- Food and Chemical Toxicology: α-Linolenic Acid: Nutraceutical, Pharmacological and Toxicological Evaluation
- Food Chemistry: Southern Australian Seaweeds: A Promising Resource for Omega-3 Fatty Acids