Understanding Conjugated Linoleic Acid (CLA)
Conjugated Linoleic Acid (CLA) is a naturally occurring fatty acid found in meat and dairy products, particularly from grass-fed ruminant animals. It is also a popular dietary supplement marketed for its potential benefits in weight loss and improved body composition. However, the CLA found in supplements is often a different form from natural sources and is delivered in much higher concentrations. This concentration difference is key to understanding the potential side effects associated with CLA supplementation.
While some research has explored CLA's benefits, a significant body of evidence has focused on its potential adverse effects, especially when taken in supplemental doses. The safety of these supplements has been a topic of debate, with studies yielding mixed results regarding their efficacy and risks.
Common and Mild Side Effects
For many people, CLA supplements may cause mild side effects, primarily related to the digestive system. These symptoms often occur at the beginning of supplementation as the body adjusts and tend to be well-tolerated, though they can be uncomfortable. Common mild side effects reported in human studies and user reviews include:
- Gastrointestinal Distress: Upset stomach, nausea, diarrhea, constipation, and bloating are frequently cited issues.
- Headaches: Some individuals experience headaches after taking CLA supplements.
- Fatigue: Feelings of fatigue or tiredness have been noted by some users.
- Skin Rashes: In rare cases, skin rashes have been reported.
Serious Health Concerns
Beyond mild discomfort, there are more significant health concerns associated with higher doses of CLA supplements, particularly for individuals with pre-existing health conditions. These risks are why consulting a healthcare provider before beginning supplementation is highly recommended.
Impact on Metabolic Health
Large supplemental doses of CLA have been linked to adverse metabolic effects, especially concerning glucose and insulin function. Research indicates that CLA supplements can:
- Worsen Diabetes and Metabolic Syndrome: For people with or at risk for these conditions, CLA can increase insulin resistance, making it harder for the body to absorb sugar effectively. This can exacerbate existing diabetes and increase the risk of developing it in those with metabolic syndrome.
Effects on the Liver
One of the more serious risks is the potential for adverse effects on liver health. High doses of supplemental CLA, much greater than what is consumed from natural food sources, may increase the accumulation of fat in the liver. This condition, known as fatty liver, is a stepping stone toward more severe metabolic issues. Studies have also indicated a possible rise in liver enzymes, suggesting liver inflammation or potential damage.
Influence on Cholesterol Levels
CLA's effect on cholesterol levels is complex and depends on the source. While dietary CLA from animal products might offer some benefits, CLA supplements have been associated with negative changes in cholesterol profiles. Some human studies have shown that supplemental CLA can:
- Lower "Good" HDL Cholesterol: Certain CLA supplements, particularly those with a higher concentration of the t10,c12 isomer, may cause a decrease in high-density lipoprotein (HDL) cholesterol levels.
- Mixed Results on Total and LDL Cholesterol: While some studies show no effect, others have found that CLA can increase triglycerides and total cholesterol.
Increased Inflammation
Chronic inflammation is a significant risk factor for various diseases, including cardiovascular issues. Some studies have found that CLA supplementation may increase levels of inflammatory markers in the body, such as C-reactive protein (CRP). This effect is particularly concerning for individuals already at risk for heart disease.
Comparison: CLA from Food vs. Supplements
| Feature | CLA from Food (e.g., grass-fed beef, dairy) | CLA from Supplements (e.g., safflower oil-based) |
|---|---|---|
| Dosage | Low, natural amounts. Typically around 150-212 mg per day from a typical Western diet. | High, concentrated doses, often 3-6 grams per day. |
| Forms of CLA | Primarily the c9, t11 isomer, which is believed to be more beneficial. | Higher proportions of the t10, c12 isomer, which is linked to more side effects. |
| Associated Risks | Low risk of side effects, generally regarded as safe. | Increased risk of metabolic, liver, and inflammatory issues, especially at higher doses. |
| Safety Profile | Widely considered safe in dietary amounts, with long-term consumption from food showing no significant risks. | Safety is debated, with concerns about long-term use and potential adverse effects at high doses. |
Who Should Avoid CLA?
Certain individuals should be particularly cautious or avoid CLA supplementation altogether due to increased risk factors:
- Pregnant or Breastfeeding Women: There is not enough reliable information on the safety of high-dose CLA supplements for these groups. It is best to avoid use.
- People with Diabetes or Metabolic Syndrome: Due to the risk of worsening insulin resistance and blood sugar control, these individuals should not take CLA.
- Individuals with Bleeding Disorders: CLA might slow blood clotting, which can increase the risk of bruising and bleeding.
- Those with Liver Disease: Given the potential for fatty liver and increased liver enzymes, CLA should be avoided by people with existing liver conditions.
- Children: Long-term safety for children has not been established.
Drug Interactions to Know About
CLA can interact with certain medications, requiring caution and a doctor's consultation. Potential interactions include:
- Blood Thinners (Anticoagulants): Because CLA might slow blood clotting, taking it with medications like warfarin or aspirin could increase the risk of bleeding.
- Diabetes Medications: CLA's effect on insulin sensitivity means it can interfere with insulin or other glucose-controlling drugs, potentially requiring dosage adjustments.
- High Blood Pressure Medications: CLA may also lower blood pressure, and combining it with antihypertensive drugs could cause blood pressure to drop too low.
Conclusion
While CLA supplements are promoted for various benefits, the evidence is mixed, and there are documented side effects and risks to consider. Mild gastrointestinal issues are common, but more serious concerns include negative impacts on metabolic health, liver function, and cholesterol levels, particularly at higher supplemental doses. The CLA from natural food sources appears safe, but the higher concentrations and different isomer composition in supplements present distinct risks. Anyone considering CLA should consult a healthcare professional to assess the potential for side effects and ensure it is safe given their individual health profile and other medications. For further reading and details on the safety and potential benefits, consider consulting reliable sources like Verywell Health.
