Conjugated Linoleic Acid (CLA): A Detailed Review 2019

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cla
Obesity is reaching epidemic proportions globally. While the solution seems straightforward, most of us know from experience that losing weight is not as simple as it sounds. As a result, there has been a considerable increase into the research undertaken on dietary supplements and medications that may have weight loss benefits.

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Interestingly, recent research into the dietary supplementation of specific fats and fatty acids has demonstrated some positive effects, in regards to both weight loss and overall health. While fats are typically used for energy, there are some specific fats that can some serious health effects.

Conjugated Linoleic Acid (CLA) is a mix of specific fatty acids that belongs to that exclusive group of fats that provides a host of health benefits.

CLA is found naturally occurring in beef and dairy, and is slowly becoming one of the most popular weight loss supplements in the world [1].

What is Conjugated Linoleic Acid?

Put simply, CLA is a type of Linoleic Acid, which is a polyunsaturated fatty acid.

Linoleic acid is one of the most commonly occurring Omega-6 fatty acids. They are found in large amounts in vegetable oils, and in trace amounts in a number of other foods. If we look at the chemical structure of Linoleic acids, they are 18 carbons in length, and contain 2 double bonds.

The word conjugated is related to the arrangement of these 2 double bonds.

In the image below, the top structure is regular Linoleic Acid. The two structures below it are the two key forms of CLA. While they look very similar, the location of the double bond is slightly different [2].

It is important to note that while this seems like quite an insignificant difference to us, it makes a huge difference on a cellular level.

So to put it simply, CLA, is a type of polyunsaturated fatty acid that is naturally occurring in foods.

As mentioned above, CLA is commonly found in beef and dairy, but can also be found in goats and sheep. The amount of CLA found in meat in particular differs significantly depending on what the animals ate within their lifetimes. CLA is typically found in much higher concentrations in grass fed animals when compared to their grain fed counterparts [3].

Due to the fact that CLA is a naturally occurring fatty acid, we do tend to consume some in our daily diet, although that amount is quite small. It is for this reason that CLA supplementation has shown to have positive effects on health. As we do not normally receive much CLA from our regular diets, additional CLA consumption can have significant benefits.

It is important to note that the CLA found in supplements does differ somewhat to the CLA found in meat and dairy, as it is derived from safflower and sunflower oils. As a result, CLA supplementation is not quite as effective as increasing our daily intake through more natural dietary methods, but is much more convenient and efficient.

CLA and weight loss

As mentioned previously, there has been extensive research into the use of CLA as an effective weight loss supplement. In fact, looking over the scientific literature, CLA may very well be the most thoroughly studied weight loss supplement available on the market today.

And for good reason too.

A 12 week long intervention of daily CLA supplementation has shown to promote significant fat loss in both overweight and obese individuals, in comparison to a control group who did not receive any CLA supplementation (and as such didn’t lose any fat mass) [4].

These results have been repeated a number of times, often demonstrated not only a decrease in body fat, but an increase in lean muscle mass as well [5][6].

Now while this is quite impressive, and actually demonstrates a lot better results than most fat loss supplements available on the market today, it is still important to note that there has also been a number of studies demonstrating that CLA supplementation has absolutely no effect on weight loss [7].

So what does this mean exactly?

Ultimately, CLA can help promote weight loss, but that weight loss is typically quite small. As a result it is not always registered as significant in some studies.

This has been confirmed by a recent review [8] which looked in depth at the results of a number of studies analysing the effects of CLA supplementation on fat loss.

They found that CLA supplementation can help promote fat loss. It appears to be most effective during the first 6 months of supplementation, and then decreases in effectiveness after that. It generally promotes approximately 0.1kg, or 0.2 pounds, of weight loss per week, for the first 6 months.

So while, it does promote fat loss, those losses are somewhat small. In saying that, as a supplement it can aid fat loss, and is likely going to be more effective in conjunction with a healthy diet, and a thorough exercise regime.

CLA and other health benefits

In conjunction with positive effects on weight loss, CLA supplementation has also shown to have some positive health effects too.

It has been shown that individuals who consume relatively high amounts of naturally occurring CLA from their diets alone are at a reduced risk of getting diabetes, heart disease, and cancer [9] [10] [11].

Again, it is important to note that CLA is naturally occurring in grass-fed animals, and the consumption of these grass fed animals have been demonstrated to have a number of positive health effects. As a result, it is hard to confirm whether these health benefits are a result of an increased consumption of CLA alone, or a side effects of an increased grass-fed meat consumption.

Despite that, we can still confirm that individuals who eat more CLA through naturally occurring dietary sources have improved health, and are less likely to develop a number of diseases including diabetes and cancer.

Side effects of CLA supplementation

As CLA supplements are made synthetically, they are significantly different to the CLA found in foods.

As a result, CLA supplementation can lead to the over consumption of specific CLA molecules, that have shown to have some side effects when consumed in high doses (although these doses are much higher than the typical supplement recommendation).

These side effects include an increased accumulation of fat in the liver, which can have additional health implications as time goes on. Extremely high doses of CLA have also shown to increase inflammation and insulin resistance, while lowering the amount of good cholesterol in the blood, which can lead to metabolic disease and diabetes.

As a result, if you are planning on supplementing with CLA, dosage should be kept between 3 and 6 grams per day.

It is also important to note that risk of side effects increases with the dosage, so it may be best to start off conservative.

In conclusion

While CLA supplementation has shown to help promote weight loss and improve some markers of health, these effects are quite minimal.

Considering this, CLA supplementation may not be worth the risk.

Although, increasing natural CLA consumption through an increase in grass-fed meat appears to have no negative side effects, and a host of benefits, including weight loss and improved health.

As such, it would be my recommendation to try and improve CLA intake through dietary means before resorting to supplementation.

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References

1. Pariza, Michael W. “Perspective on the safety and effectiveness of conjugated linoleic acid.” The American journal of clinical nutrition 79.6 (2004): 1132S-1136S. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/15159246

2. Banni, Sebastiano. “Conjugated linoleic acid metabolism.” Current opinion in lipidology 13.3 (2002): 261-266. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/12045395

3. Dhiman, T. R., et al. “Conjugated linoleic acid content of milk from cows fed different diets.” Journal of Dairy Science 82.10 (1999): 2146-2156. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/10531600

4. Blankson, Henrietta, et al. “Conjugated linoleic acid reduces body fat mass in overweight and obese humans.” The Journal of nutrition 130.12 (2000): 2943-2948. Viewed at: http://jn.nutrition.org/content/130/12/2943.short

5. Watras, A. C., et al. “The role of conjugated linoleic acid in reducing body fat and preventing holiday weight gain.” International journal of obesity 31.3 (2007): 481-487. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/16924272

6. Chen, Shu-Chiun, et al. “Effect of conjugated linoleic acid supplementation on weight loss and body fat composition in a Chinese population.” Nutrition28.5 (2012): 559-565. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/22261578

7. Larsen, Thomas Meinert, et al. “Conjugated linoleic acid supplementation for 1 y does not prevent weight or body fat regain.” The American journal of clinical nutrition 83.3 (2006): 606-612. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/16522907

8. Whigham, Leah D., Abigail C. Watras, and Dale A. Schoeller. “Efficacy of conjugated linoleic acid for reducing fat mass: a meta-analysis in humans.”The American Journal of Clinical Nutrition 85.5 (2007): 1203-1211. Viewed at: http://ajcn.nutrition.org/content/85/5/1203.long

9. Heinze, Verónica M., and Adriana B. Actis. “Dietary conjugated linoleic acid and long-chain n-3 fatty acids in mammary and prostate cancer protection: a review.” International journal of food sciences and nutrition 63.1 (2012): 66-78. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/21762028

10. Castro-Webb, Nelsy, Edward A. Ruiz-Narváez, and Hannia Campos. “Cross-sectional study of conjugated linoleic acid in adipose tissue and risk of diabetes.” The American journal of clinical nutrition 96.1 (2012): 175-181. Viewed at: http://www.ncbi.nlm.nih.gov/pubmed/22648724

11. Smit, Liesbeth A., Ana Baylin, and Hannia Campos. “Conjugated linoleic acid in adipose tissue and risk of myocardial infarction.” The American journal of clinical nutrition 92.1 (2010): 34-40. Viewed at: http://ajcn.nutrition.org/content/92/1/34


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About the Author John Wright

John has been a fitness enthusiast for over 10 years, starting out while struggling with obesity as a teenager. Over the years he has advised numerous clients on how to transform their physiques and their lives. As a writer on Nutrition Inspector he aims to help others achieve real results by staying clear of the common hype and false claims in the supplement industry!

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