onjugated linoleic acids are a group of fatty acids that are found in meat and dairy items derived from ruminants. They comprise of at least 28 isomers of linoleic acid that are either a trans fatty acid or cis fatty acid. Conjugated linoleic acid is widely available as a dietary supplement all over the world. The United States Food and Drug Administration has included conjugated linoleic acid in the GRAS (generally recognized as safe) category. 
In 1932, the existence of CLA was reported in a research paper. However, the complex and unique structure of conjugated linoleic acid was not identified until the 1980s. At first, it was discovered in beef. The primary dietary sources of conjugated linoleic acids are ruminant products. 
Since 1980, scientific studies have investigated the potential health benefits of conjugated linoleic acid as a functional food ingredient. It has gained a great deal of popularity because of its various biological activities. Conjugated linoleic acid possesses the ability to improve lean body mass, modulate immune and inflammatory responses, reduce body fat and avert the development of atherosclerosis. In addition to all these benefits, it is also known to act as an anticancer agent. 
Health Benefits of Conjugated Linoleic Acid
There are multiple ways in which eating food containing conjugated linoleic acid or taking conjugated linoleic acid supplement can benefit your overall health and help you cope with certain health conditions.
Here is a list of some of the scientifically-proven health benefits of conjugated linoleic acid:
1. Helps Reduce Body Fat and Supports Weight Loss
It is a well-documented fact that conjugated linoleic acid is a useful supplement for diminishing fat mass in animals. However, its efficacy in reducing fat mass in human beings is still being studied. An analysis of 18 studies concluded that a dose of 3.2 g/d conjugated linoleic acid could produce a modest loss in body fat in human beings. 
A study involving a group of overweight women found that daily intake of CLA (conjugated linoleic acid) supplement resulted in 9% body fat loss within a year. Jean-Michel Gaullier, an expert in the field, has published a study in the American Journal of Clinical Nutrition stating that conjugated linoleic acid supplementation can yield promising results. His research proves that conjugated linoleic acid can cause safe and effective weight loss.
A total of 180 overweight individuals participated in this study. Out of them, 149 were women while 31 participants were men. The body mass index (BMI) of all the participants was between 25 to 30. It is usually found that people whose BMI is above 25 are highly susceptible to heart diseases and other excess weight-related problems like diabetes. All the participants were divided into three groups. Two groups were given conjugated linoleic acid pills or conjugated linoleic acid syrup daily, while the third group was given a placebo capsule containing olive oil.
The participants in the three groups consumed same quantity of calories every day and performed similar exercises. The study lasted for 12 months during which all the participants regularly visited the clinic to record their weight and body mass index and also for blood tests. At the end of the 12-month study period, it was found that participants in the first two groups who took conjugated linoleic acid pills or syrup lost around 4 pounds of weight. The individuals who took the conjugated linoleic acid syrup experienced 9% body fat loss, while the ones who took the CLA pill lost 7% body fat. The people in these two groups also experienced improvements in muscle mass. On the other hand, the individuals in the third group who took placebo pills did not experience any weight loss or body fat loss. 
2. Improves Immune Function
A double-blind, randomized study was conducted to check the effect of conjugated linoleic acid on the immune system. The study involved 28 healthy participants, both men and women, between the age of 25-50. Few subjects received conjugated linoleic acid supplements in soft-gel capsules, while others received placebo capsules containing high oleic sunflower oil. The participants took 3 grams of supplements every day for 12 weeks. At the end of the study, it was reported that conjugated linoleic acid was able to affect the immune function in the participants beneficially. This study was the first study to show that conjugated linoleic acid, a type of fatty acid that is mostly found in dairy and meat products, can improve the immune function of the body. 
Conjugated linoleic acid possesses the ability to affect several parameters related to immunity. This compound can cause an increase in the production of eicosanoids and immunoglobulins. Both these biological mediators are essential for the functioning of the immune system. They cause multiple effects on the immune cells and can affect a range of biological functions. 
3. Improves Insulin Sensitivity and Regulates Blood Sugar
A few researches involving animal subjects suggest that conjugated linoleic acid may have anti-diabetic property. These trials found that conjugated linoleic acid intake resulted in reduction in fasting glucose and insulin concentrations. A study was conducted to examine the effect of conjugated linoleic acid supplementation in improving insulin sensitivity in human beings. A total of sixteen young sedentary individuals participated in this study. Ten participants were given conjugated linoleic acid isomers for eight weeks, while the other six participants received placebo containing safflower oil. After 4 and 8 weeks of supplementation, oral glucose tolerance tests of the subjects were performed. At the end of this randomized clinical trial, it was concluded that a common dosage of a commercial conjugated linoleic acid supplement could improve insulin sensitivity in young individuals who live a sedentary life.  Another study conducted at Purdue University, Indiana, found that conjugated linoleic acid can effectively improve insulin levels and cause a moderate reduction in the blood glucose level and triglyceride levels in people who have diabetes. 
4. Helps Reduce Cancer Risk
The anticancer role of CLA has been investigated in the last few years. It was found that this compound has a wide array of positive effects on cellular mechanisms in both, normal and cancer cells. Even though a majority of the studies and clinical trials to check the anticancer role of conjugated linoleic acid has been done on animal subjects, few research reports have suggested that conjugated linoleic acid can have anticarcinogenic effects on human beings. A study conducted in Finland found that dietary conjugated linoleic acid consumption led to a decrease in the risk of breast cancer. A similar study was conducted in France with 360 participants who had breast cancer. As per the findings of this study, it was established that higher the level of conjugated linoleic acid in breast adipose tissue, lower the incidences of breast cancer. 
5. Helps Fight Asthma
Studies have found that conjugated linoleic acid can prove to be beneficial for people who have asthma.  A few researchers from St. Paul’s Hospital and the University of British Columbia conducted a study to examine the ability of conjugated linoleic acid in reducing airway hyperactivity in asthma patients. A total of 28 overweight adults took part in this study for 12 weeks.The subjects were divided into two categories. One group was given conjugated linoleic acid while the other group took a placebo. The group that took CLA reported a significant reduction in the airway hyperactivity.
6. Helps Fight Rheumatoid Arthritis
Rheumatoid arthritis is a chronic inflammatory disorder that causes pain and discomfort in the joints. This disease affects the lining of the joints and its symptoms include swelling, tenderness and stiffness in joints, fatigue, fever and sudden weight loss. 
A study was carried out to examine the effect of conjugated linoleic acid (CLA) on bone markers in this chronic disease. The study involved 52 subjects who had rheumatoid arthritis. All of the participants were divided into two groups. One group was given CLA capsules while the other one received placebo capsules containing sunflower oil packed with a high quantity of oleic acid. At the end of this randomized double-blind clinical trial, it was found that conjugated linoleic acid had a beneficial effect on bone markers of subjects who took CLA supplements daily. Thus, it was established that conjugated linoleic acid can effectively help people who suffer from rheumatoid arthritis. 
It is believed that the presence of omega-3 essential fatty acids in conjugated linoleic acid enables it to provide relief from morning stiffness and pain associated with diseases like rheumatoid arthritis and osteoarthritis. 
Apart from the benefits stated above, there are many other ways in which conjugated linoleic acid can benefit your health. It is believed to improve well-being in people suffering from hay fever. Research suggests that consumption of a diet containing a high quantity of conjugated linoleic acid can lower the risk of colon and rectum cancer in women. Few studies have also found that when taken with creatine and whey protein, conjugated linoleic acid can increase strength. This can help people who practice strength training.
Dietary Sources of Conjugated Linoleic Acid
You can either take conjugated linoleic acid regularly or consume food items that are replete with it. However, be mindful of the fact, that the content of CLA is not the same in all the dietary sources. Here is the concentration of conjugated linoleic acids in different products: 
Precautions and Possible Side Effects
While taking conjugated linoleic acid, it is crucial to take certain precautions. It is considered to be safe for children when taken by mouth in medicinal amounts for not more than seven months. On the other hand, pregnant and breastfeeding women should avoid taking conjugated linoleic acid, as there is not enough evidence to know the type of effect it can have on a woman during pregnancy. Individuals who suffer from bleeding disorders should stay away from conjugated linoleic acid as it could increase the risk of bruising and bleeding.
In general, taking conjugated linoleic acid is considered to be safe for most people when taken by mouth in food and medicinal amounts. However, at times, it could cause side effects like diarrhea, nausea, fatigue, headache and backache. 
Recommended Dosage of Conjugated Linoleic Acid
According to scientific research, conjugated linoleic acid should be taken by mouth. For obese individuals who want to reduce body fat, the recommended dosage of conjugated linoleic acid is 1.8-7 grams per day. Meanwhile, for people who want to lower high blood pressure, the recommended dosage is 4.5 grams per day. 
Due to its many health-benefiting properties, conjugated linoleic acid has become extremely popular all over the world. Found primarily in food items derived from ruminant animals, conjugated linoleic acid is an extremely potent compound that has been investigated by scientists over the last many decades. Numerous evidence-backed clinical trials have established that conjugated linoleic acid possesses a plethora of health benefits. From improving the immune system of the body to burning fat, there are plenty of ways in which it can help promote your physical wellness. As discussed earlier, you can either take conjugated linoleic acid supplements daily or consume dairy and meat products derived from ruminant animals. However, if you are suffering from a health problem, then it is highly recommended to check with your doctor before taking a new supplement.