PepRank

Lactium (alpha-s1 casein hydrolysate)

Also: alpha-casozepine · bioactive milk peptides · casein decapeptide · Zylkene (the veterinary version)

SupplementAnxietyOral

Milk-protein decapeptide for stress and sleep; gentle, non-sedating, slow to build.

Safety tier
Clean
strict bar
Positive
52%
of 11 reports
Per month
≈ €12–23
by mouth
Rank
#7
of 23 supplements

At a glance

Access
Supplement
OralFelt in 7 days – 4 weeks

Builds over days or weeks of regular use rather than with each dose.

Best effects
Calmer under stress without sedation · easier to fall back asleep after night waking · builds over several days
Downsides
Fragmented sleep or extra waking for some · afternoon fatigue or flatness at higher doses · many products are blends, so hard to judge alone · dairy-derived (milk allergy)
Typical use
150-300 mg/day (trials used 150 mg for stress, 300-600 mg for sleep), at bedtime or split morning and night.
Stacked with
Stacked with
L-theanine: commonly paired for daytime calm; one trial tested the two head to head · jujube seed and hops: the Australian 'Advanced Sleep' blend behind the strongest report · magnesium glycinate: common bedtime pairing

Safety

Tier by safety barStrict CleanBalanced CleanEvidence only Clean
  • Seen harm0 of 3
  • Mechanism0 of 3
  • Data gap1 of 3
  • Silent harm0 of 3
  • Product0 of 3
Never if
Cow's milk allergy
Why each score
Seen harm 0/3
Small RCTs found it well tolerated and first-hand reports mention only fragmented sleep or daytime flatness. Kim et al. 2019: alpha-s1 casein hydrolysate and sleep, crossover RCT n=48 (PubMed 31252661) ↗Kim et al. 2007: alpha-s1 casein hydrolysate and stress symptoms in women, n=63 (PubMed 17136040) ↗
Mechanism 0/3
A milk-protein hydrolysate whose active decapeptide (alpha-casozepine) acts weakly on GABA-A receptors; no pathway to serious harm is known.
Data gap 1/3
A dairy-derived ingredient with a 2004 US new-dietary-ingredient notification and several small RCTs (n=36-63), many maker-funded; EFSA assessed only its efficacy claim. Kim et al. 2019: alpha-s1 casein hydrolysate and sleep, crossover RCT n=48 (PubMed 31252661) ↗EFSA 2011: Lactium stress claim not substantiated (efficacy opinion) ↗
Silent harm 0/3
Any effect is felt the same night or day and stops with the product.
Product 0/3
OTC capsules from mainstream supplement brands, often in blends.

User reports

All 12 reports →
Users report
Few people talk about it, and the reports are short. Users who like it describe a quiet calm with no sedation, help getting back to sleep when stress or 'high cortisol' wakes them, and an effect that builds over a few days. Several of the warmest reports come from blends with jujube and hops, so Lactium's share of the effect is unclear. A minority feel nothing. A few relaxed users still wake more often or feel flat or crash in the afternoon, and one person could not tolerate it. Felt nothing: ~20% of reports; Reddit coverage is thin (about a dozen first-hand reports).
Glowing 1Positive 5Mixed 3Nothing 2
  • r/Supplements· · 5 upvotesOriginal ↗

    I take Nature's Own Advanced Sleep - best sleep of my life; deep, refreshing and uninterrupted with no hangover. Stuff is a deadset miracle for me and I have tried everything.

    Glowing112.5 mg Lactium in a blend · Oral · staying asleep

    Nature's Own Advanced Sleep blend (Lactium + jujube seed + hops); credits the blend, not Lactium alone

  • r/Biohackers· · 8 upvotesOriginal ↗

    While you're figuring it out, the 2 most helpful products I've found are [lactium]

    PositiveAnxiety · Oral · stress / high-cortisol feeling

    Swanson women's anti-stress (Lactium 167 mg); one of two most helpful products while finding the root cause

  • r/ouraring· · 1 upvotesOriginal ↗

    Even after taking two pills of l-theanine and lactium. I feel fatigue:/

    Nothingtwo pills with L-theanine · Oral

    Oura ring user; still fatigued after L-theanine plus Lactium

Where to buy

All 1 offers →
Getting it
Sold as Lactium (Ingredia) in stress and sleep capsules, e.g. Swanson 'Women's Anti-Stress', Life Extension 'Bioactive Milk Peptides' and Nature's Own Advanced Sleep, often blended with jujube, hops or L-theanine.

A month at 150–300 mg/day costs ≈ €12–23 from iHerb at €2.59/g.

No trusted shop in the EU lists it; every listing is on the buy page.

Studies

Evidence
Human RCTs — N of 36-63; on stress symptoms, blood-pressure response to stress and sleep; mixed objective results, and much of the trial base is manufacturer-linked
Caveat
Most trials are small, many were funded by the ingredient maker, and subjective sleep scores often improve as much on placebo. The veterinary version (Zylkene) is widely used for anxious pets, but owners' reports about pets are not first-hand evidence. A dairy protein with no safety signal in humans.
2 more studies and 2 sources

Sources

Molecule

Sequence
YLGYLEQLLR
Length
10 amino acids
Modifications
representative: αs1-casein f91-100 (α-casozepine) within a casein hydrolysate mixture

Sequence

The peptide's chain of amino acids from its start (the N-terminus) to its end, one bead and one letter for each: A alanine, C cysteine, D aspartic acid, E glutamic acid, F phenylalanine, G glycine, H histidine, I isoleucine, K lysine, L leucine, M methionine, N asparagine, P proline, Q glutamine, R arginine, S serine, T threonine, V valine, W tryptophan, Y tyrosine. A modification such as an N-acetyl cap or a C-terminal amide changes how long it lasts in the body. Length tells related peptides apart, from a two-residue dipeptide like carnosine to a 43-residue protein like thymosin beta-4, and predicts neither effect nor safety.

Report grades

Every first-hand Reddit or X report is graded on its own, from glowing through positive, mixed, nothing and negative to bad reaction, and the bar shows how those grades split. Posts that look vendor-adjacent stay on the peptide's page but are left out of the counts.

GlowingPositiveMixedNothingNegativeBad reaction

% positive

The share of a peptide's graded Reddit and X reports that are glowing or positive, vendor-adjacent posts left out. A peptide with few reports is pulled toward the average of all reports, as if it had eight average ones besides its own, so two glowing posts cannot top the list. Peptides rank by this figure, those with no graded report yet after those with one, and Avoid ones after every other entry.

Researcher estimate

No first-hand report of this peptide has been graded yet, so the figure is the researchers' own rating out of 10 from what they read about it. It ranks after every peptide with graded reports until its own arrive.

Safety tier

Each peptide is tiered Clean, Caution or Avoid from its five risk axes under the chosen safety bar. An Avoid peptide carries a real risk of harm, a plausible route to serious harm rather than mere unpleasantness, so it stays listed with the reason but ranks behind every other entry, however good its reviews.

Safety bar

The safety bar sets how much risk it takes to rate a peptide Avoid. Strict: out on any serious mechanism with little human data, or any documented serious harm. Balanced: out on documented serious harm (unless it is obvious, reversible and from a regulated product), or a serious mechanism whose harm would be silent with no human data at all. Evidence only: out only on documented serious harm in humans that is lasting, delayed or from grey-market product.

Seen harm

Documented serious adverse events in humans, from 0 for none despite real exposure to 3 for deaths or several well-documented serious harms. Serious means a hospital or emergency visit or harm lasting weeks, so a headache or a bad night does not count.

Mechanism

A plausible biological route to serious harm at the doses people use, such as growth-factor signalling, hormone-axis suppression, heart or blood-pressure effects or immune activation. It runs from 0 when none is known to 3 when a dangerous pathway has been shown in living animals.

Data gap

How little human safety data exists for the molecule actually sold, from 0 for an approved drug with large trials and years of use to 3 for no human safety data at all. A modified analogue does not inherit its parent's trials.

Silent harm

Whether the feared harm would show quickly or stay hidden, from 0 when it is obvious and goes on stopping to 3 when it is silent and delayed, like tumour promotion or slow organ damage. User reports cannot reveal a harm that takes years to appear, so a high score here limits what good reviews can tell you.

Product

The risk of what people actually buy, from 0 for a regulated pharmacy or supplement product taken by mouth or on the skin to 3 for a grey-market injectable. In one dataset of 6,441 grey-market samples, 42–71% failed basic quality criteria and 15% carried endotoxin; taken by mouth or in the nose, a pack avoids the injection risks.

Evidence

The strongest kind of study behind the peptide's effects, from an approved drug through human controlled trials and small human studies to animal work or nothing of its own. Animal results often fail to carry over to people.

Access

How people get it: as an approved drug, a compounded prescription, an over-the-counter supplement or from the grey market, where nobody checks the vial. The channel decides both the legal position and the risk of a bad batch.

Price per month

Thirty days of the typical dose, from its low end to its high end, priced at the listing a careful buyer would choose: in stock, from a shop scoring 4 of 5 on trust (third-party tested where no score is set), failing that 3, a pure pack before a blend, a European shop first, then the cheapest per mg. The range is the dose's, not the shops'. A per-dose amount counts once a day unless the dose says otherwise. Prices are in euros at ECB rates of 2026-10-29, before shipping; the shop table keeps each listing's price per mg, per gram for bulk supplements. Where no listing can be priced the researchers' own estimate stands in, and says so.

Dose users report

The middle half of the daily doses stated in at least five first-hand reports, vendor posts left out. Where its middle sits more than twice above or below the declared dose, the month is priced at it as well, since what people take is what they pay for.

Shop trust

Each shop's trust on a 1–5 scale, read from its testing and its reputation: 1 for serious red flags (fabricated COAs, scam reports, impersonation, a closed shop), 2 for no public testing, a new shop or active complaints such as seized parcels, 3 for its own COAs or a short track record, 4 for verified third-party testing or a strong reputation, and 5 for third-party batch reports that name the shop, with years of good independent reputation. A shop without a score counts third-party batch testing as 4, its own COAs as 3 and no public tests as 2.

Best value

Within a category or a goal, a peptide that no other beats on both counts: none is rated more positively for the same or a lower monthly price, and none costs less for the same or a higher rating. The chart joins these into the best-value line; the cheapest of them and the best-rated of them both make it, so the line spans the trade-off from cheap to best. Avoid entries never count, and a peptide needs both a % positive and a price to be compared.

Testing

Whether the shop publishes lab results: third-party tested means an independent lab checks each batch, own COA means the shop's own certificate of analysis, and no public tests means neither. A certificate shows purity, not safety.

Added peptide

Some packs sold under one peptide's name hold a second one, such as 5 mg GHK-Cu in a nasal kit, stated only in the description. Sprayed in the nose or injected it reaches the blood like an injection, so it carries the risk of that route and is tiered as the injectable form, whatever its tier on the skin. A pack whose page gives no contents list may hold more than its name.