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Limited evidencePhysical performance

Alpha-Ketoisocaproate (KIC)

The keto acid of leucine, marketed for recovery and anti-catabolic effects. Human data amount to a handful of small trials, and the one positive result used KIC combined with arginine, not KIC alone.

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What the science says

  • Exercise performance Limited evidence

    A randomized controlled trial of short-term KIC supplementation found no meaningful improvement in exercise performance. Sample sizes in this literature are in the dozens at most.

  • High-intensity muscle performance with arginine Limited evidence

    An earlier randomized trial reported enhanced high-intensity dynamic muscle performance from a combination of arginine and KIC. Because the two were given together, the contribution of KIC by itself cannot be separated.

  • Protein metabolism in clinical settings Limited evidence

    A randomized controlled study in post-surgical patients compared branched-chain amino acids and KIC on protein metabolism. This is clinical nutrition research and does not transfer to healthy trainees.

Dosage & safety

Studied doseNo established sports dose. Trials used roughly 1.5–3 g/day, often paired with arginine; clinical infusion studies used higher amounts under supervision.
SafetyShort-term oral use in small trials produced no serious adverse effects; gastrointestinal upset is the usual complaint. Long-term safety is unknown, and people with liver or kidney disease should not use keto acid supplements without medical advice.

How to take it

TimingTiming does not matter.
With food?Take it with food, since GI upset is the usual complaint.
Worth knowingKeto acid supplements are used clinically in kidney disease under supervision, which is a reason to check with a doctor rather than a reason to assume they are gentle.

Interactions

With other supplements

  • leucine and BCAA products

    KIC is a leucine metabolite, so the two cover the same ground. there is little point running both

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does KIC (alpha-ketoisocaproate) improve exercise performance?

A randomised trial found short-term alpha-ketoisocaproate (KIC) produced no meaningful improvement in exercise performance, and the evidence is limited. The one positive KIC result used a combination with arginine, so KIC's own contribution cannot be separated.

How much KIC should I take?

Alpha-ketoisocaproate has no established sports dose; trials used roughly 1.5–3 g/day, often paired with arginine. Take KIC with food, since stomach upset is the usual complaint.

Is KIC safe?

Short-term oral alpha-ketoisocaproate produced no serious adverse effects in small trials, but long-term safety is unknown. People with liver or kidney disease should not use KIC or other keto acid supplements without medical advice.

Should I take KIC with leucine or BCAAs?

Alpha-ketoisocaproate (KIC) is a leucine metabolite, so KIC and leucine or BCAA products cover the same ground and there is little point running both.

Scientific references

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