Maybe you’ve heard that consuming too many omega-6 fatty acids can lead to health issues like inflammation and cardiovascular disease, but did you know that omega-6s, like linoleic acid, are actually essential nutrients that need to be consumed by humans for proper brain function, metabolism and development?
Unfortunately, in Westernized societies, the average consumption of omega-6 fatty acids far exceeds the nutritional requirements. So instead of focusing on the benefits of these polyunsaturated fatty acids, we usually hear about their pro-inflammatory properties when eaten in excess. However, eating organic, non-GMO sources of linoleic acid can reduce your risk of cardiovascular disease, boost the health of your brain and even improve your reproductive health.
Linoleic acid, which accounts for approximately 90 percent of dietary intake of omega-6 fatty acids, plays an important role in many biochemical processes. But it’s important to learn about the best food sources and exactly how much of these fats you should consume regularly.
What Is Linoleic Acid?
Linoleic acid is a polyunsaturated essential fatty acid that is found mostly in plant oils. It’s known as the parent fatty acid of the omega-6 series, and it is essential for human nutrition because it cannot be synthesized by the human body.
In scientific terms, linoleic acid is a nutrient from the carbonyl functional group that contains two double bonds at the ninth and 12th carbons. Why is linoleic acid essential? Because humans cannot incorporate a double bond beyond the ninth carbon of the fatty acid, so it can’t be synthesized naturally and must be consumed.
Like all fatty acids, linoleic acid is used by the body as a source of energy. It is a substrate for the synthesis of physiological regulators that are called eicosanoids, including prostaglandins, prostacyclins, thromboxanes and leukotrienes. These are “local hormones” that serve as mediators of many biochemical processes, like the regulation of blood pressure, blood lipid levels, immune function, blood clotting, inflammation and reproduction.
Linoleic acid is also an important structural component of cell membranes and affects cell membrane properties like fluidity, flexibility and permeability.
Although eating omega-6 foods can be beneficial to our health for a number of reasons, consuming these fatty acids in excess can be problematic. It’s easy to consume too much linoleic acid because these oils are typically used to make processed foods, which are eaten too often in Western societies.
That’s why it’s important to consume the right balance of omega-3 and omega-6 fatty acids, at about a 1:1 to 2:1 ratio. When consumed, linoleic acid can be desaturated into other omega-6s, like arachidonic acid, which is then converted to compounds called eicosanoids. These compounds are important for the normal metabolic function of our cells and tissues, but when they are produced in excess, they can contribute to a number of chronic diseases. This is exactly why we need to be careful with our omega-6 fatty acid intake.
Eating foods high in linoleic acid, but keeping the proper balance with omega-3 foods, can help to boost cardiovascular health, brain function, immunity, skin health and bone strength. This acid is present in vegetable oils like sunflower and safflower oils.
Vs. Conjugated Linoleic Acid
CLA, or conjugated linoleic acid, refers to a group of conjugated octadecadienoic acid isomers that are derived from linoleic acid. Microbes in the gastrointestinal tract of ruminants (like grass-fed beef and lamb) convert linoleic acid into CLA through a process called biohydrogenation. CLA is structurally similar to linoleic acid, with the only difference being the location of their two double bonds.
The benefits of CLA include its ability to help with weight loss, improve immune function, regulate blood sugar levels, boost cardiovascular health, and promote proper growth and development. CLA is found naturally in foods, like grass-fed meat and dairy products.
Vs. Oleic Acid
Oleic acid is a monounsaturated omega-9 fatty acid that is not considered “essential” because it is made by the human body. There are many omega-9 benefits, so consuming foods containing oleic acid can help to reduce your risk of cardiovascular disease, increase your energy levels and boost brain function.
Oleic acid is found in vegetable and animal fats, with olive oil being the most common source of the omega-9. Some other oleic acid food sources include hazelnuts, macadamia nuts and sunflower oil.
Foods and Oils
Linoleic acid is the most highly consumed polyunsaturated fatty acid found in the human diet. In the U.S., the typical intake is about 6 percent of energy. Currently, soybean oil accounts for approximately 45 percent of dietary linoleic acid in the standard American diet.
Wondering what foods are high in linoleic acid? Here’s a general breakdown of linoleic acid foods and oils and h0w many grams are in a serving, according to the Linus Pauling Institute at Oregon State University and the United States Department of Agriculture’s Agricultural Research Service:
- Safflower oil: 10 grams in 1 tablespoon
- Sunflower seeds: 9.7 grams in 1 ounce
- Pine nuts: 9.4 grams in 1 ounce
- Soybean oil: 8.9 grams in 1 tablespoon
- Sunflower oil: 8.9 grams in 1 tablespoon
- Corn oil: 7.3 grams in 1 tablespoon
- Pecans: 6.4 grams in 1 ounce
- Sesame oil: 5.6 grams in 1 tablespoon
- Brazil nuts: 5.8 grams in 1 ounce
Meat — including beef, lamb and chicken — milk, cheese and eggs are also good sources of linoleic acid, but the content depends on the lifestyle and diet of the animals. Products that come from grass-fed animals have a higher linoleic acid content.
1. May Reduce Risk of Cardiovascular Disease
Studies show that consuming linoleic acid may help to lower LDL cholesterol, improve blood pressure and reduce your overall risk of cardiovascular disease.
In 2009, the American Heart Association published an advisory recommending that at least 5 percent to 10 percent of energy from omega-6 fatty acids, primarily linoleic acid, reduces the risk of cardiovascular disease, concluding that reducing intake levels would likely increase the risk. Researchers have contended that this is true when there’s a proper balance of omega-3 and omega-6 fatty acids, with a 1:1 ratio.
In 2014, researchers at the University of Minnesota School of Public Health conducted an analysis of cohort studies with over 310,000 subjects. They examined the studies and found that dietary linoleic acid in the highest category corresponded to a 15 percent lower risk of coronary heart disease relative to the lowest category. Replacing 5 percent of energy from saturated fatty acids with linoleic acid was associated with a 9 percent reduction in coronary heart disease events and a 13 percent lower risk of death from coronary disease.
We should note that there have been studies indicating that linoleic acid does not reduce the development of heart disease, so a definitive conclusion about the benefits of linoleic acid for cardiovascular health isn’t possible at this time. However, the research done so far has been promising.
2. Promotes Healthy Brain Function
There’s significant evidence that linoleic acid plays a critical role in our cell membranes, which impacts healthy brain function. Researchers have found that brain unesterified linoleic acid concentration increases following a brain injury, which suggests that linoleic acid or its metabolites may be involved in the natural response to injuries involving the brain. Animal studies indicate that this acid may be involved in neurotransmission and participates in the response to ischemic brain injury, such as stroke.
Studies also indicate that mood disorders are correlated with very low concentrations of linoleic acid. One study found that there was a slight decrease of linoleic acid in the decision-making area of the brain in depressed or bipolar suicidal subjects, and very low concentrations of this acid were present in the platelets of subjects with suicide attempts.
3. Supports Skin and Hair Health
A deficiency in linoleic acid may lead to scaly and itchy skin, which has been shown in animal studies. Linoleic acid has a direct role in maintaining the water permeability barrier of the skin, thereby improving skin hydration. It also helps modulate the closure of skin wounds, and it reduces skin inflammation and acne. Plus, a major metabolite of linoleic acid possesses anti-proliferative properties, which means that it can help prevent the spread of malignant cells into surrounding tissues.
Research also suggests that using oils high in linoleic acid, like safflower and argan oil, on your hair may help promote hair growth and may serve as a natural treatment for thinning hair. Linoleic acid is a precursor of arachidonic acid, an omega-6 fatty acid that promotes the expression of several factors responsible for hair growth.
4. Improves Reproductive Health
Impaired reproductive health is a symptom of linoleic acid deficiency. Because linoleic acid contains essential components of all cell membranes, it can influence reproductive processes and alter the production of prostaglandins. Plus, the reproductive system requires a high polyunsaturated fatty acid content to provide plasma membranes with the fluidity that’s essential at fertilization.
An animal study published in Advanced Pharmaceutical Bulletin found that linoleic acid supplementation promoted estrogenic activity and improved the reproductive performance of female rats with their ovaries removed. Researchers concluded that these results indicate the acid’s potential beneficial role in the treatment of postmenopausal and menopause symptoms, including hot flashes, vaginal atrophy, reduced cardiovascular health and the development of osteoporosis.
5. Boosts Immune Function
Polyunsaturated fats in both the omega-6 and omega-3 families are useful in human autoimmune-inflammatory disorders. Research conducted at the University of Greenwich at Medway’s School of Chemical and Life Sciences in the U.K. found that omega-6 fatty acids help prevent or reduce the severity of autoimmune disease by enhancing immune function and regulating cellular immune reactions.
However, this is only true when you eat a healthy balance of omega-3s and omega-6s. When you eat an excessive amount of omega-6 foods, like products made from vegetable oils, it has a pro-inflammatory response.
6. Protects Bone Density
Human studies support a greater intake of polyunsaturated fatty acids, including both omega-3 and omega-6 fatty acids, for higher bone mineral density and the reduced risk of fragility fracture. These fatty acids influence bone cell metabolism, help to preserve skeletal formation and may help to reduce the risk of osteoporosis and fractures.
It’s not hard to come by foods containing linoleic acid, since most processed and packaged foods are prepared with vegetable oils containing the polyunsaturated fat. But in order to benefit from linoleic acid consumption, it’s best to consume the fat in organic, non-GMO whole foods, including grass-fed beef, chicken, eggs and plant-based oils. Continue to avoid eating too many unhealthy foods that contain linoleic acid, including processed meats, potato chips and store-bought salad dressings.
There are supplements available that contain both omega-6 and omega-3 fatty acids, which help you keep the balance that’s needed for optimal health.
Although there is no specific recommended daily allowance for linoleic acid, adequate intakes have been approximated based on median intakes of healthy individuals living in the U.S. Here’s a breakdown of adequate intakes of linoleic acid for children and adults, according to research published in the international review journal Advances in Nutrition:
- Adult men (19–50 years old): 17 grams per day
- Adult women (19–50 years old): 12 grams per day
- Adult men (51–70 years old): 14 grams per day
- Adult women (51–70 years old): 11 grams per day
- Children (1–3 years old): 7 grams per day
- Children (4 years to adulthood): progressively increases from 7 grams per day as they grow older
- Infants (0–6 months): 4.4 grams per day
- Infants (7–12 months): 4.6 grams per day
Risks and Side Effects
Is linoleic acid bad for you? Consuming too many omega-6 fatty acids and not enough omega-3s can throw off your fatty acid balance, which can lead to inflammation and a number of serious health issues. For this reason, focus on eating natural sources of this acid from organic, non-GMO and whole foods. Avoid eating processed and packaged foods that contain vegetable oils containing omega-6s, and keep your balance of omega-3 and omega-6 foods at a ratio of about 1:1 to 2:1.
There is some research suggesting that high intakes of polyunsaturated fatty acids among pregnant women can impact omega-3 fatty acid levels in developing fetuses. However, researchers indicate that the adverse effects of excess linoleic acid intake relative to omega-3s requires more research at this time.
- Linoleic acid is a polyunsaturated omega-6 fatty acid that’s known as an essential fatty acid because it can’t be made by the human body.
- There’s strong evidence that eating a diet with the proper balance of omega-3 and omega-6 fatty acids can help to: reduce your risk of cardiovascular disease, improve brain function, boost skin and hair health, improve reproductive health, boost immune function, and strengthen bones.
- What is a good source of linoleic acid? The best food sources include organic, non-GMO vegetable oils, like sunflower oil, and nuts, seeds, meat products, eggs, cheese and milk.