Conjugated linoleic acid (CLA) is a group of polyunsaturated fatty acids commonly found in beef, lamb and dairy products. In the last few years, numerous studies have been done on CLA and its many health benefits.

According to studies, these good fats have protective effects against cancer, obesity, diabetes, and atherosclerosis.

This article focuses on health benefits, mechanism of action and the side effects of dietary CLA on human health.

What is conjugated linoleic acid?

Conjugated linoleic acid is an omega-6 fatty acid which is commonly found in vegetable oils and other animal-based foods like beef and butter.

It is a type of polyunsaturated fatty acid which contains both cis and trans double bonds. Though technically a trans fat, CLA is actually beneficial for the body and it is known for its cancer-fighting properties. It also helps in weight loss and muscle-building.

How does CLA work?

All types of fats are made up of fatty acids. Fatty acids can be saturated, monosaturated and unsaturated, depending on their chemical structure.

When a carbon atom is bonded to hydrogen, saturated fat is formed. A monosaturated fat is created if one pair of carbon atom forms a bond. When there are more than two unsaturated bonds, polyunsaturated fat is formed.

Conjugated linoleic acid is polyunsaturated fat, specifically an omega-6 fatty acid. The microbes living in the gastrointestinal tract of ruminant animals convert linoleic acid to form CLA through a biohydrogenation process.

This process changes the fat’s double bonds to form a single bond between one or both of the two double bonds.

We need the correct amount of both omega-3 and omega-6 fatty acids in our diet. Conjugated linoleic acid is an omega-6 fat that we can eat more of as it acts like an omega-3 food and helps lower inflammation.

They also help regulate ghrelin, the hunger hormone, and improve your ability to absorb nutrients.

There are 28 different forms of CLA. Foods contain mostly c9, t11, while supplements are high in t10, c12. This is the reason why CLA taken in supplement form does not have the same effect as conjugated linoleic acid taken from foods.

In 1987 researchers first discovered the role that CLA plays in fighting cancer in mice (1). In 1997 researchers found that CLA could also help in reducing body fat levels (2).

Health benefits of conjugated linoleic acid

There has been a significant amount of research on the health benefits of conjugated linoleic acid. Let us read about some of the benefits of conjugated linoleic acid.

1. Loss of body fat

Many animal-based and human studies have shown that CLA helps with fat loss. A  report on the antiobesity mechanisms of conjugated linoleic acid was published in The Journal of Nutritional Biochemistry in 2009 (3).

According to the report, the potential mechanisms responsible for the antiobesity properties of CLA include –

  • Decreased energy intake by suppressing appetite
  • Increasing energy expenditure in WAT, muscle, and liver tissue
  • Decreasing adipogenesis
  • Increased lipolysis
  • Apoptosis via stress, inflammation or insulin resistance.

During a 2007 study, 118 people were given CLA or placebo over six months. The results showed that CLA helped decrease body fat mass and increased lean body mass (4).

However, some other studies have shown absolutely no effect of CLA in reducing weight (5). Some people experience better results due to factors like CLA isomer combination, CLA dose and duration, gender, age, and metabolic status.

2. Helps improve insulin function

CLA intake can help reduce the risk of developing diabetes. According to a 2012 study, CLA is involved in insulin regulation (6). Foods that contain CLA like grass-fed beef and butter can stabilize blood sugar and is beneficial in controlling diabetes.

According to studies, CLA actions can mimic the effect of diabetic drugs. When mice with type-2 diabetes were given CLA, it helped improve insulin action and reduced circulating glucose.

3. Cancer prevention

Research has shown that conjugated linoleic acid is essential for reducing overall cancer risk. CLA help lower inflammation, which helps lower cancer risk.

Studies have shown that women who have a lot of CLA in their diet, have a lower risk of colorectal cancer and breast cancer (7).

Though the research on the effects of CLA on breast cancer is conflicting, some reports suggest that a higher intake of conjugated linoleic acid from natural foods can lower the risk of developing breast cancer.

4. Reduces symptoms of asthma

People develop asthma when they produce higher levels of leukotrienes, the fatty molecules of the immune system. Leukotrienes are a thousand times more potent than histamine at causing bronchial constriction.

These leukotrienes are produced when 5-lipox acts on arachidonic acid in the body. CLA helps reduce 5-lipox and arachidonic acid inflammation without harming the arteries.

It does this by converting CLA inside the body to form DHA and EPA, both of which have anti-inflammatory properties. According to a 2010 study, 12 weeks of supplementation with CLA improved airway hyperresponsiveness in the subjects (8).

5. Lowers risk of heart disease

CLA helps convert stored fat into energy, and this may prevent heart diseases like atherosclerosis. According to the Pennington Biomedical Research Center, CLA prevents the deposition of lipids and plaque in arteries, which is a key cause for heart disease.

CLA reduces lipid levels such as triglycerides and cholesterol. It also prevents heart disease by acting as an antioxidant and by lowering blood pressure.

CLA also helps prevent atheromatous lesions which are essential in reducing the risk of stroke and heart attack.

6. Prevents rheumatoid arthritis

Dietary conjugated linoleic acid can prevent rheumatoid arthritis and other inflammatory diseases. CLA inhibits bone resorption, increases the endocortical bone formation and modulates the action of COX enzyme (9).

When taken with vitamin E, conjugated linoleic acid also helps in reducing the symptoms of arthritis like pain and morning stiffness.

7. Improves muscle strength

According to a recent study, the combination of creatine monohydrate and conjugated linoleic acid after resistance exercise can improve strength and body composition in older adults.

This beneficial effect of CLA is why it is gaining popularity as a bodybuilding supplement.

Best natural sources of CLA

According to the Linus Pauling Institute, we must consume around 3 grams of CLA daily. Beef from grass-fed cows is one of the best sources of CLA. Here are some of the best sources of CLA –

  1. Grass-fed beef: 30 mg per gram of fat
  2. Cheese from grass-fed cow milk: 20 to 30 mg per gram of fat
  3. Milk from grass-fed cows: 20 to 30 mg per gram of fat
  4. Lamb: 5.6 mg per gram of fat
  5. Whole milk: 5.5 mg per gram of fat

Grass fed animal foods have higher amounts of conjugated linoleic acid. This is because these animals consume more omega-6 fatty acids and in turn, they produce more quantities of CLA.

Cows that are fed corn and other foods that are unnatural for their diet do not produce much CLA.

Natural sources vs supplements

Though it is possible to get CLA from supplements, you may not be able to get the same benefits from them as you get from conjugated linoleic acid in real foods.

The CLA found in supplements is different from the CLA found in foods. Whole foods are made up of c9, t11 CLA, while supplements are high in t10, c12 CLA.

While CLA supplements can help lower the risk and manage the symptoms of certain diseases, it lacks rumenic acid. Rumenic acid forms about 90 percent of the CLA found in grass-fed meat and dairy products.

Conjugated linoleic acid found in supplements is made by chemically altering linoleic acid from unhealthy vegetable oils.

Side effects and interactions of CLA supplements

Conjugated linoleic acid is generally considered safe when taken in the form of whole foods or in limited amounts in the form of supplements. For some people taking CLA supplements can cause side effects. Here are some of the side effects of CLA:

1. Fatigue

Conjugated linoleic acid supplements can lead to fatigue in some people. This may affect your ability to remain active during normal daily activities.

2. Diarrhea

Episodes of diarrhea accompanied by pain, cramping and bloating can occur after you take a dose of conjugated linoleic acid. If diarrhea persists, you can also become dehydrated.

3. Nausea

In some people, conjugated linoleic acid supplements can also cause nausea and loss of appetite.

4. Not for children

CLA supplements are not advisable for children as their long-term effects are not known.

5. Additional health concerns

If you have a history of heart disease and diabetes, consult a physician before taking these supplements. People who are about to go for surgery or have a history of poor liver function and bleeding disorders should not take CLA supplements as these supplements are known to slow down blood clotting and increase the risk of bruising.

Final thoughts

Conjugated linoleic acid is a type fatty acid commonly found in dairy products and beef. These fatty acids help in weight loss, improving muscle strength, cancer protection and also lower the risk of heart disease.

Usually considered safe when taken in the form of whole foods, CLA supplements can have some side effects. So, include butter from grass-fed cows, grass-fed beef and grass-fed dairy in your daily meals to enjoy the numerous health benefits of conjugated linoleic acid

Conjugated linoleic acid or CLA is an omega-6 fatty acid which is commonly found in vegetable oils and other animal-based foods like butter