Health Benefits of Conjugated Linoleic Acid

Can the weight loss aid deliver on its promise?

closeup hand holding fish oil vitamin for healthy
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If you've ever been on a weight loss or muscle-building journey, you may have come across conjugated linoleic acid (CLA). That's because it's most commonly marketed as a weight-loss supplement that increases fat-burning and supports lean muscle. If it sounds too good to be true, it may be.

Conjugated linoleic acid (CLA) is an omega-6 fatty acid found naturally in dairy products and beef, especially those on a grass-fed diet. The amount of CLA in today's beef and dairy products has greatly declined due to changes in cattle farming and their diet. Because of this, scientists explored ways to synthesize CLA from other sources in the lab such as sunflower or safflower oil.

CLA is popular in the athletic and bodybuilding communities as a supplement that can reduce fat, build muscle, and increase energy and endurance.

Despite its popularity, the evidence is not clear-cut making it difficult to determine if CLA is beneficial or not.

Health Benefits

A quick google search will bring about an endless supply of research proposing the benefits of CLA. Navigating through that research can be tedious and confusing. The most encouraging health benefits of CLA include weight loss, blood sugar control, and immune system health.

The way in which CLA promotes benefits body composition and weight loss is through a few different mechanisms—increasing fat-burning while limiting the amount of body fat that can be stored, all while preserving muscle. That's what makes it so intriguing to athletes and bodybuilders. The problem is much of the research contradicts one another.

A review of studies published in the American Journal of Clinical Nutrition concluded that CLA, taken at a dose of 3.2 grams per day, produced only a minor loss in body fat (average 0.05kg) compared to a placebo.

In the same year, another review published in Public Health Nutrition reported no difference between the bodyweight or composition of those who took CLA versus those who took a placebo.

Recently, this study revealed that participants who took CLA for 3 months saw a significant decrease in body fat and leptin secretion (a hormone released by body fat that helps control body weight), which means it could be helpful for weight loss.

Another review compared the effects of CLA on animals versus the effects on humans and found that CLA does in fact offer some degree of fat loss on both animals and humans. However, more research is needed.

Keeping your blood sugar within normal limits is important to prevent and treat type 2 diabetes. CLA's benefits on blood sugar have been studied extensively with some promise.

In mice, CLA reduced fasting blood glucose, increased glucose tolerance, and improved glycolipid metabolism.

Other older studies in humans found supplementing with CLA had a beneficial effect on blood glucose and type 2 diabetes.

What's confusing though is that some research produced opposite findings. For instance, this study following 116 overweight or obese adults resulted in no improvements in insulin resistance or glucose metabolism after supplementing with CLA for 6 months. Another study had similar findings.

While CLA is not a treatment for type 2 diabetes, it may offer some benefits for improving blood sugar levels. But with conflicting evidence, you can see how this may be confusing.

Maximizing immune health is on almost everyone's to-do list these days and CLA may be a good fit in your supplement routine. Not only has CLA been shown to enhance the body's immune system response, but it's also been shown to provide anti-inflammatory properties that reduce inflammation.

On the other hand, this review outlines a number of studies that found CLA has no effect on immune system function.

It's difficult to determine whether CLA can offer any health benefits. Because there are so many inconclusive studies, more research is needed.

Possible Side Effects

Conjugated linoleic acid supplements are generally considered safe if taken as prescribed. Some people may experience side effects, usually mild, including an upset stomach, diarrhea, nausea, fatigue, headache, and backache.

Conjugated linoleic acid may also slow blood clotting. Taking a CLA supplement along with an anticoagulant ("blood thinners") or nonsteroidal anti-inflammatory drug (NSAID) can further enhance this effect, leading to easy bruising and bleeding.

Possible drug interactions include:

  • Advil (ibuprofen)
  • Aleve (naproxen)
  • Aspirin
  • Advil (ibuprofen)
  • Coumadin (warfarin)
  • Fragmin (dalteparin)
  • Heparin
  • Lovenox (enoxaparin)
  • Plavix (clopidogrel)
  • Voltaren (diclofenac)

Dosage and Preparation

Conjugated linoleic acid supplements are typically produced as a gel cap and filled with either sunflower or safflower oil. CLA is classified by the U.S. Food and Drug Administration as GRAS ("generally regarded as safe") and typically prescribed at between 3 grams and 6 grams per day. Doses up to 6 grams per day have no reported serious side effects.

What to Look For

Conjugated linoleic acid is found naturally in grass-fed beef and lamb, as well as milk and other milk products. You can also find eggs fortified with CLA at some grocery stores. Portobella mushrooms and acorn mushrooms are good plant-based sources of CLA.

When choosing a CLA supplement, look for brands that put their products through third-party testing by certifying bodies including U.S. Pharmacopeia (USP), NSF International, or ConsumerLab, to ensure quality and safety standards are met.

Conjugated linoleic acid is not considered an essential nutrient like vitamins and minerals. Taking them or not taking them will likely have little tangible impact on your health.

If you do decide to use them, talk with a medical professional to understand the potential risks and benefits of treatment. This is especially true if you have diabetes or are on blood thinners. In cases like these, CLA may cause more harm than good.

Frequently Asked Questions

  • What is the best time to take conjugated linoleic acid?

    The best time to take conjugated linoleic acid is right before or with a meal to help reduce risk of unpleasant side effects.

  • Where can I buy conjugated linoleic acid?

    Conjugated linoleic acid (CLA) is available online as well as in local grocery stores and natural food and nutrition stores.

  • How fast does conjugated linoleic acid work?

    Results are not rapid with conjugated linoleic acid. You can expect to find the best results within 1-6 months of use.

  • What foods should I eat when taking conjugated linoleic acid?

    You can take CLA on an empty stomach, however, it's recommended to take conjugated linoleic acid with a meal or right before.

17 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Shoshana Pritzker RD, CDN, CSSD, CISSN
Shoshana Pritzker RD, CDN is a Sports and Pediatric Dietitian, the owner of Nutrition by Shoshana, and is the author of "Carb Cycling for Weight Loss." She's been writing and creating content in the health, nutrition, and fitness space for over 15 years and is regularly featured in Oxygen Magazine, JennyCraig.com, and more.