What is Conjugated Linoleic Acid (CLA)?
Conjugated linoleic acid (CLA) is a naturally occurring omega-6 fatty acid primarily found in the meat and dairy products of ruminant animals like cattle and sheep. In food sources, CLA exists mainly in the cis-9, trans-11 isomer form. The CLA found in dietary supplements, however, is manufactured by chemically altering linoleic acid from vegetable oils, such as safflower or sunflower oil. This process creates different isomers of CLA, most notably the trans-10, cis-12 isomer, which is believed to be responsible for some of the adverse effects associated with supplementation. Supplemental doses are significantly higher than the amounts obtained from a regular diet.
The Risks of Taking Too Much CLA
While moderate intake of supplemental CLA (typically 3 to 6 grams per day) is generally considered safe for most adults, increasing the dosage significantly heightens the risk of adverse effects. The potential side effects range from mild discomfort to more serious metabolic issues.
Common Side Effects of High-Dose CLA
- Gastrointestinal Distress: Many people experience digestive issues such as stomach upset, nausea, diarrhea, and indigestion when taking high doses of CLA. These symptoms are often more pronounced during the initial weeks of supplementation.
- Fatigue and Headaches: Other general malaise symptoms can include fatigue and headaches.
- Inflammation: Some studies suggest that supplemental CLA may increase markers of systemic inflammation in the body.
Serious Health Risks
Excessive, long-term intake of supplemental CLA has been linked to more severe health complications. Unlike naturally occurring CLA from food, the high doses found in supplements can disrupt normal metabolic processes.
- Insulin Resistance and Diabetes: Several studies, particularly in animals but also in humans, have shown that high doses of supplemental CLA can cause insulin resistance. This is a condition where the body's cells don't respond effectively to insulin, leading to elevated blood sugar levels. For individuals with existing diabetes or metabolic syndrome, this can be particularly dangerous.
- Fatty Liver: A concerning side effect is the potential for increased fat accumulation in the liver, a condition known as fatty liver. Animal studies have shown this outcome, which can serve as a stepping stone toward metabolic syndrome.
- Changes to Cholesterol Levels: While some isomers of CLA have shown mixed results regarding cholesterol, large doses of supplements have been observed to lower "good" HDL cholesterol levels. This is a negative outcome for cardiovascular health.
- Bleeding Disorders: CLA supplements may slow blood clotting. This is a potential risk for individuals with bleeding disorders or those on blood-thinning medications.
Who Should Be Cautious with CLA?
Several groups of people should approach CLA supplementation with extreme caution or avoid it entirely due to heightened risks:
- Individuals with diabetes or metabolic syndrome
- People with liver disease or heart conditions
- Pregnant and breastfeeding women
- Anyone with a known bleeding disorder or taking anticoagulant medications
Comparison: Natural CLA vs. Supplemental CLA
| Feature | Natural Food Sources | CLA Supplements |
|---|---|---|
| Source | Ruminant meat (e.g., grass-fed beef), dairy (e.g., milk, butter) | Chemically altered vegetable oils (e.g., safflower oil) |
| Dosage | Very small, natural amounts. Average intake is in milligrams (mg). | Concentrated, high doses measured in grams (g). |
| Primary Isomer | Predominantly cis-9, trans-11 | Often a mix of cis-9, trans-11 and trans-10, cis-12 |
| Safety Profile | Considered safe and beneficial in natural quantities. | Potential for side effects, especially with high doses or long-term use. |
| Health Effects | Linked to reduced risk of diseases in observational studies. | Associated with mild to serious adverse metabolic effects at high doses. |
Long-Term Effects and Overall Supplement Safety
Long-term studies on the effects of high-dose supplemental CLA are limited, and results have been inconclusive or raised red flags. The potential for long-term health risks, including metabolic changes and liver issues, means that consumers should weigh the modest, and often unreliable, weight loss benefits against the possible health dangers. The risks increase as dosage and duration of use increase. Always consult with a healthcare professional before starting any new supplement regimen to ensure it is appropriate for your individual health status. For comprehensive information on supplementation safety, you can visit the Operation Supplement Safety website.
Conclusion
While conjugated linoleic acid from natural food sources is part of a healthy diet, taking excessive amounts via supplements can be harmful. Studies show that high doses can lead to significant side effects, including gastrointestinal problems, insulin resistance, and potential liver damage. The safe and effective dose, typically between 3 and 6 grams per day, must be respected to minimize risk. For individuals with pre-existing conditions like diabetes or heart disease, supplemental CLA may not be safe at all. Consumers must be aware of the difference between natural dietary CLA and concentrated supplemental forms, and prioritize professional medical advice over anecdotal claims regarding this and any other dietary supplement.
