Overview

Conjugated linoleic acid (CLA) is a type of unsaturated fat found in beef and dairy products. Although it is sometimes used for high cholesterol and weight loss, it does not seem to be helpful. A common side effect is an upset stomach. There is also some concern that when CLA is taken regularly for a long time, it may be harmful. Before taking CLA, make sure to tell your health care provider about any health conditions you have or medicines you are taking.

Uses

What is conjugated linoleic acid (CLA) used for?

CLA may be used for high cholesterol and weight loss, but it does not seem to be beneficial for these uses.

Note: The FDA has not reviewed CLA for safety and effectiveness. Learn more about dietary supplements here.

How does CLA work (mechanism of action)?

Conjugated linoleic acid (CLA) is a type of unsaturated fatty acid that is found in beef and dairy products. There are two forms (isomers) of this fatty acid: c9,t11 CLA and t-10,c-12 CLA. Each of these forms is thought to have different effects in the body. Most dietary supplements that contain CLA are made from sunflower oil, safflower oil[1] , or corn oil, which contain both forms of CLA.

Although there is interest in taking CLA for high cholesterol and weight loss, most research shows that it does not improve cholesterol levels or help with weight loss. In fact, some studies show that taking CLA may lower the levels of “good” cholesterol (HDL) in your body without lowering the levels of “bad” cholesterol (LDL).

There is also some concern that taking CLA supplements may cause harm to your body over time. Although some research shows that CLA may act as an antioxidant, other research shows that it can act as a prooxidant. This means that it could cause damage to certain cells in the body, especially when taken in the higher doses found in supplements. This risk may be higher in people with certain conditions, including diabetes and obesity.

How should I store CLA?

You should store CLA according to the product label. Most dietary supplements should be kept in a cool, dry location that is out of the reach of children and pets and not in direct sunlight.

Side Effects

What are the most common side effects of CLA?

The most common side effect of CLA is an upset stomach. Side effects may vary depending on the dose you are taking or the specific product you are using. Tell your health care provider if you have any side effects that bother you.

There may be other side effects of CLA that are not listed here. Contact your health care provider if you think you are having a side effect of a supplement. In the U.S., you can report side effects to the FDA at www.safetyreporting.hhs.gov or by calling 888-SAFEFOOD (888-723-3366). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of CLA?

While less common, the most serious side effects of CLA are described below, along with what to do if they happen.

Severe Allergic Reactions. CLA may cause allergic reactions, which can be serious. Stop taking CLA and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Trouble swallowing or throat tightness
• Itching or skin rash
• Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain

Precautions

Who should not use CLA?

Allergies to Ingredients. People who are allergic to any of the following should not take CLA.

• Conjugated linoleic acid (CLA)
• Any of the ingredients in the specific product

Your pharmacist can tell you all of the ingredients in the specific CLA products they stock.

What should I know about CLA before using it?

CLA is a dietary supplement. It cannot be marketed to treat or cure a disease.

Read and follow the directions on the specific product you are taking, or take it as recommended by your health care provider.

Keep CLA out of the reach of children.

The FDA has not tested CLA products to confirm that they contain the ingredients stated on their labels. Some dietary supplements have been tested by third-party organizations to confirm that they contain the ingredients listed on their labels and do not contain any harmful chemicals. Learn more about how to choose a safe dietary supplement product here.

What should I tell my health care provider before using CLA?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if CLA is right for you.

In particular, make sure that you discuss any of the following.

Food Allergy.Supplements that contain CLA may be made from soy oil, safflower oil, or corn oil. You may be at risk of an allergic reaction to these supplements if you have an allergy to soy, safflower, or corn. Review the product label carefully to find the source of CLA. Before taking CLA, tell your health care provider if you are allergic or think that you may be allergic to any of these foods.

Other Current and Past Health Conditions.Tell your health care provider if you have any of the following, especially if you plan to take CLA for a long time.

• Diabetes or prediabetes
• Heart problems
• Liver problems
• Low levels of “good” cholesterol (HDL)
• Overweight or obesity

Other Medicines and Supplements.CLA may interact with other medicines and supplements. Before taking CLA, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. It is not known if or how CLA could affect pregnancy or harm a fetus. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if CLA passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed.

Interactions

Does CLA interact with foods or drinks?

There are no known interactions between CLA and foods or drinks.

It is unknown if drinking alcohol will affect CLA.

Does CLA interact with medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking CLA.

• A blood thinner, which is a medicine used to treat or prevent blood clots
• An antiplatelet medicine, such as aspirin/dipyridamole, cilostazol, clopidogrel (Plavix), or ticagrelor (Brilinta), which is a medicine used to prevent blood clots
• A medicine for diabetes
• A medicine to lower cholesterol or triglyceride levels

The interactions between CLA and medicines are not fully understood. As with most dietary supplements, the research on drug interactions with CLA is incomplete. Always check with your health care provider before taking CLA with any medicines.

Dosing

What should I do if I accidentally use too much CLA?

If you or someone else has used too much CLA, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

CLA comes in a wide range of doses, depending on your reasons for using it. There is some concern that taking CLA regularly for a long time may be harmful for some people. Read the product label closely, and speak with a health care provider about how to take CLA safely. Do not take double or extra doses, even if you miss a dose.