Supplement analysis backed by scientific evidence · PT

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Limited evidenceWeight management

CLA (Conjugated Linoleic Acid)

CLA reduces fat mass by roughly 0.1 kg per week in pooled trials — a trivially small effect that fades after about six months. More importantly, the trans-10,cis-12 isomer that drives fat loss also worsens insulin sensitivity and inflammatory markers, which makes the risk-benefit unfavourable.

What the science says

  • Very small reduction in fat mass Moderate evidence

    A meta-analysis of 18 randomized trials found CLA at about 3.2 g/day reduced fat mass by roughly 0.09 kg per week versus placebo, with the effect plateauing around six months. That is under 2 kg over a year of continuous supplementation, at doses that cause GI side effects in many users.

  • Impairs insulin sensitivity Moderate evidence

    A randomized trial in abdominally obese men found that purified trans-10,cis-12 CLA induced hyperproinsulinemia and reduced insulin sensitivity compared with placebo and with a CLA isomer mixture. Several other trials report increases in inflammatory markers, oxidative stress and lipoprotein(a). This is the main reason to be cautious with CLA in anyone with metabolic syndrome or prediabetes.

  • Preserves lean mass or improves body composition in athletes Limited evidence

    Effects on fat-free mass in pooled human data are minimal and not consistently significant. There is no credible evidence that CLA enhances strength, hypertrophy or athletic performance in humans, despite persistent marketing to that effect.

Dosage & safety

Studied doseTrials typically used 3.0-6.8 g/day of a 50:50 mixture of the cis-9,trans-11 and trans-10,cis-12 isomers, for 6-24 months. Given the modest benefit and metabolic downsides, there is no dose we would positively recommend.
SafetyGI side effects (nausea, loose stools, dyspepsia) are common at typical doses. The trans-10,cis-12 isomer is associated with insulin resistance, raised inflammatory and oxidative stress markers, and lower HDL. Multiple case reports link high-dose CLA to hepatitis and elevated liver enzymes, with resolution on withdrawal — stop immediately if you develop jaundice, dark urine or right upper quadrant pain. Avoid in people with diabetes, prediabetes, metabolic syndrome, or existing liver disease. Not recommended in pregnancy or lactation (it reduces milk fat content).

Scientific references

Where to buy

NatureWise, CLA , 180 Softgels

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