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Moderate evidencePhysical performance

Milk Protein Isolate

Whole milk protein with the lactose and fat removed, keeping the natural roughly 80:20 casein-to-whey ratio. It is a good, slow-and-fast blended protein source, though few trials test this exact ingredient rather than milk or whey.

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What the science says

  • Lean mass with resistance training Moderate evidence

    A randomized trial in novice male weightlifters found that fat-free fluid milk after resistance exercise produced greater lean mass accretion over 12 weeks than soy or carbohydrate. The trial was small and used milk rather than the isolated powder.

  • Protein supplementation generally Strong evidence

    A meta-analysis and meta-regression of 49 randomized trials found supplemental protein increases fat-free mass and strength gains during resistance training. Milk protein was among the most commonly used supplements in those trials.

  • Animal versus plant protein Moderate evidence

    A systematic review and meta-analysis of randomized trials found a small advantage for animal protein over plant protein for lean mass, mainly in younger adults. The difference is modest and largely disappears when total protein and leucine are matched.

Dosage & safety

Studied dose20–40 g per serving. The casein fraction slows digestion, which makes it a reasonable choice before longer gaps between meals or before bed.
SafetyWell tolerated by most. Contains milk protein, so it is unsuitable for milk allergy; residual lactose is low but not always zero. No specific risks beyond those of any concentrated protein source.

How to take it

TimingThe casein fraction digests slowly, so this is a sensible choice before bed or before a long gap between meals.
With food?With or without food.
Worth knowingResidual lactose is low but not always zero, so a milk protein isolate is not a safe substitute for whey isolate if lactose is a real problem for you.

Interactions

With medications

  • levodopa

    A protein load competes with levodopa for absorption and brain uptake. separate the shake from your levodopa dose by at least 1 hour

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

Frequently asked questions

Is milk protein isolate good for building muscle?

Milk protein isolate is a good protein source: a meta-analysis of 49 trials found supplemental protein, with milk protein among the most common, increases muscle and strength gains during resistance training (strong evidence). Few trials test milk protein isolate itself rather than milk or whey.

Milk protein isolate vs whey: what's the difference?

Milk protein isolate keeps milk's natural roughly 80:20 casein-to-whey ratio, so it digests more slowly than whey. That makes milk protein isolate a sensible choice before bed or a long gap between meals.

How much milk protein isolate should I take?

Take 20–40 g of milk protein isolate per serving. Separate it from levodopa by at least 1 hour, since a protein load competes with the drug.

Is milk protein isolate lactose-free?

Milk protein isolate has low residual lactose, but not always zero, so it is not a safe swap for whey isolate if lactose is a real problem for you. It is unsuitable for milk allergy.

Scientific references

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