Understanding the Risks of Supplemental CLA
While small amounts of naturally occurring conjugated linoleic acid (CLA) found in meat and dairy products are considered safe, the synthetic, concentrated doses in dietary supplements are a different matter. Research has uncovered several potential health complications and contraindications associated with high-dose supplemental CLA, leading experts to advise against its use for certain individuals. Before considering CLA supplementation, it is vital to understand who is at risk and why.
Individuals with Diabetes and Metabolic Syndrome
One of the most significant warnings about CLA concerns its impact on blood sugar regulation. Multiple studies have shown that supplemental CLA can worsen insulin resistance, particularly the trans-10,cis-12 isomer often found in supplements. For those with type 2 diabetes or metabolic syndrome, this effect can be particularly dangerous, potentially leading to poor glycemic control and increased health risks. The impaired insulin function can also promote the accumulation of fat in the liver, which can lead to further complications. Therefore, individuals with these conditions should explicitly avoid CLA supplementation.
Those with Heart Conditions and Poor Cholesterol Profiles
Counterintuitively, some research suggests that while natural CLA might be beneficial for heart health, supplemental CLA could have negative effects. Some human trials have shown that concentrated CLA can lower levels of high-density lipoprotein (HDL), or "good" cholesterol, and increase markers of inflammation. These effects could potentially increase the risk of cardiovascular issues. Furthermore, supplemental CLA has been observed to worsen endothelial function, which can be a risk factor for heart disease. Individuals with existing heart disease or poor lipid profiles should consult a doctor before considering CLA.
Patients with Liver Disease
Several reports have linked the use of CLA supplements to liver problems, in some cases severe enough to require a liver transplant. While liver injury is a rare side effect, the possibility exists, especially with high doses. This accumulation of fat in the liver (hepatic steatosis) is a known adverse effect observed in animal studies and has also been documented in humans taking supplemental CLA. Anyone with a history of liver disease or impaired liver function should consider this a major red flag and avoid the supplement entirely.
Individuals on Blood-thinning or Blood Pressure Medication
CLA supplementation can interfere with the body's blood-clotting mechanisms. For people on anticoagulant or antiplatelet drugs, taking CLA could increase the risk of bruising and uncontrolled bleeding. Additionally, CLA might have blood pressure-lowering effects, which could cause blood pressure to drop too low when combined with antihypertensive medications. It is crucial to inform a healthcare provider about all supplements, including CLA, to prevent dangerous drug interactions.
Pregnant and Breastfeeding Women and Children
Safety data regarding the use of supplemental CLA in pregnant or breastfeeding women and children is largely insufficient. Given the lack of reliable evidence, healthcare professionals advise these groups to avoid supplemental CLA as a precautionary measure. The effects of supplemental CLA on infant development and long-term health in children are not well understood, and the potential risks outweigh the unproven benefits.
Comparison of CLA Supplementation Risks
| Condition / Population | Primary Concern with Supplemental CLA |
|---|---|
| Diabetes / Metabolic Syndrome | Worsened insulin resistance, poor blood sugar control |
| Heart Disease | Reduced HDL cholesterol, increased inflammation |
| Liver Impairment | Potential for liver damage and fat accumulation |
| On Blood-thinners | Increased risk of bleeding and bruising |
| On Blood Pressure Medication | Risk of dangerously low blood pressure |
| Pregnant or Breastfeeding | Insufficient safety data, avoid use |
| Children | Long-term effects unknown, avoid use |
Who Should Avoid Supplemental CLA?
- Individuals with pre-existing diabetes or metabolic syndrome due to the risk of exacerbating insulin resistance.
- Patients with a history of heart disease or high cholesterol, especially given the potential for reduced 'good' cholesterol.
- Anyone with liver disease or compromised liver function, as supplemental CLA has been linked to liver damage.
- People taking anticoagulant or antiplatelet drugs to avoid heightened bleeding risks.
- Patients on medication for high blood pressure to prevent blood pressure dropping to an unsafe level.
- Pregnant or breastfeeding women as safety has not been established.
- Children, particularly for long-term use, as research is lacking.
- People with known bleeding disorders due to CLA's effect on blood clotting.
- Individuals preparing for surgery should stop taking CLA at least two weeks prior to reduce the risk of bleeding.
Conclusion
While some animal studies and limited human trials have explored the potential benefits of conjugated linoleic acid, the evidence is not strong enough to recommend supplemental CLA for the general population. More importantly, a significant body of research highlights serious risks for certain groups, including those with metabolic issues, heart conditions, and liver problems, as well as individuals on specific medications. Ultimately, the potential for modest, short-term weight loss effects is likely outweighed by the risks of adverse health outcomes. For most people, seeking natural CLA from grass-fed dairy and meat is a safer alternative. As with any supplement, a thorough discussion with a healthcare provider is essential before taking conjugated linoleic acid.
Talk to your doctor or pharmacist before starting a new supplement.
