Ingredient reference cards

Alpha hydroxy acid · 90 Da

What it does

Loosens the bonds between surface corneocytes so they shed. Also acts as a humectant, which makes it the gentlest AHA.

Suits

Dullness, rough texture, mild dryness, first-time acid users, most Fitzpatrick types.

Evidence

Reviews of alpha hydroxy acids describe dose-dependent effects: low concentrations act as humectants and reduce corneocyte cohesion, while higher concentrations cause epidermolysis. Clinical reviews support improved texture, hydration and tone with regular low-strength use, alongside a clear photosensitivity signal.

Do not layer with

Other exfoliants in the same routine. Retinoid in the same application.

Photosensitivity — sun protection required. One exfoliating step only. Not on a compromised barrier.

“"It's a lactic acid at a stated concentration. It's the mildest of the exfoliating acids and it holds water at the same time, so it suits skin that's dull and a bit dry."”

• Dual effects of alpha-hydroxy acids on the skin — Molecules (2018)
• Evaluating the efficacy and safety of alpha-hydroxy acids in dermatological practice — Clin Cosmet Investig Dermatol (2024)

Alpha hydroxy acid · 76 Da, the smallest

What it does

Same mechanism as lactic acid, but the smaller molecule penetrates further and works faster. More effective and more irritating.

Suits

Texture and tone in resilient skin. Congestion.

Evidence

Glycolic acid peel reviews document improvement in photodamage, acne and pigmentation, with efficacy tied to concentration, pH and contact time. Peeling literature in darker skin repeatedly flags post-inflammatory hyperpigmentation as the dominant complication, which is why gentler agents are preferred as a starting point.

Do not layer with

Other exfoliants. Retinoid in the same application.

Highest irritation potential of the AHAs. **Elevated PIH risk in Fitzpatrick IV to VI** — prefer lactic. Photosensitivity. Not on a compromised barrier.

“"Glycolic is the strongest of the common exfoliating acids. If your skin marks easily after a breakout, we'd usually start you somewhere gentler."”

• Glycolic acid peel therapy — a current review — Clin Cosmet Investig Dermatol (2013)
• Chemical peeling in ethnic / dark skin — Dermatol Ther (2004)

Beta hydroxy acid · oil-soluble

What it does

Being oil-soluble, it enters the sebaceous follicle rather than working only on the surface. Clears the plug from inside. Also anti-inflammatory.

Suits

Oily skin, congestion, blackheads, whiteheads, inflammatory acne.

Evidence

A comprehensive review of salicylic acid as a peeling agent supports serial superficial peels for acne and congestion, with comparatively low post-inflammatory hyperpigmentation rates in darker skin. Acne pregnancy reviews advise against extensive high-strength use.

Do not layer with

Other exfoliants. Retinoid in the same application.

**Pregnancy — refer, do not supply.** Drying with overuse. One exfoliating step only.

“"Salicylic is oil-soluble, so it gets into the pore rather than sitting on top of it. That's why it's the one used for congestion."”

• Salicylic acid as a peeling agent: a comprehensive review — Clin Cosmet Investig Dermatol (2015)
• Management of acne in pregnancy — Am J Clin Dermatol (2024)

Retinoid · two conversion steps from retinoic acid

What it does

Normalises the way follicles shed cells, speeds turnover, influences pigment transfer, and supports the dermal matrix over months. The best-evidenced topical for photoageing.

Suits

Photoageing, texture, congestion, uneven tone. Long-term use.

Evidence

Randomised trials and antiaging systematic reviews place retinoids at the top of the cosmeceutical evidence base for wrinkling and photodamage, with measurable change read at 12 weeks and beyond rather than in weeks. Retinisation-type dryness and scaling is the expected early adverse effect in these trials.

Do not layer with

AHA or BHA in the same application. Benzoyl peroxide.

Note

Introduce: 2 to 3 nights weekly for 2 to 4 weeks, then build. Buffer with moisturiser first if irritating. Retinisation: Dryness and flaking in weeks 1 to 6 is expected and settles. **Sustained burning, swelling or weeping is not — stop and refer.**

**Contraindicated in pregnancy and breastfeeding.** Not on isotretinoin or within ~6 months of finishing. Not on a compromised barrier. Increases photosensitivity — sun protection mandatory.

“"It's a retinol. It's the most studied ingredient for sun damage and texture, but it takes a few months and it needs sunscreen alongside it. We start you two nights a week."”

• Cosmeceuticals for antiaging: a systematic review of safety and efficacy — Arch Dermatol Res (2024)
• Randomised double-blind assessment of topical bakuchiol and retinol for facial photoageing — Br J Dermatol (2019)
• Management of acne in pregnancy — Am J Clin Dermatol (2024)

Retinoid ester · the weakest form

What it does

Converts to retinol, then retinaldehyde, then retinoic acid. One step further from active than retinol, so markedly weaker at the same percentage.

Suits

Very sensitive skin, or a gentle introduction to vitamin A.

Evidence

Human skin model work comparing vitamin A esters shows retinyl palmitate has the least favourable metabolic conversion and the lowest retinoid-related bioactivity of the esters studied, which is the mechanistic basis for treating it as the mildest option rather than an equivalent one.

Do not layer with

AHA or BHA in the same application. Benzoyl peroxide.

Note

1% retinyl palmitate is **not** comparable to 1% retinol. If a client makes that comparison, correct it.

As retinol — **contraindicated in pregnancy and breastfeeding.**

“"It's a gentler form of vitamin A. It's the mildest in the family, so it's a reasonable starting point — but it's not as strong as retinol at the same number."”

• Retinyl propionate has a unique metabolic profile and higher bioactivity over retinol and retinyl palmitate in human skin models — Exp Dermatol (2021)
• Physiological role of retinyl palmitate in the skin — Vitam Horm (2007)

Meroterpene from *Psoralea corylifolia* · not a retinoid

What it does

Produces some gene expression effects comparable to retinoids, by a different route. Better tolerated.

Suits

People who cannot tolerate retinoids.

Evidence

A randomised, double-blind, twelve-week comparison of bakuchiol 0.5% with retinol 0.5% reported comparable reductions in wrinkle surface area and hyperpigmentation, with significantly less scaling and stinging in the bakuchiol arm. It is one trial, and it does not establish general equivalence.

**Pregnancy safety data is limited — refer, do not substitute for a retinoid in pregnancy.** Not established as equivalent to retinol.

“"Bakuchiol isn't vitamin A, but it behaves a little like it and it's much better tolerated. It's the option if retinol doesn't agree with you."”

• Prospective, randomised, double-blind assessment of topical bakuchiol and retinol for facial photoageing — Br J Dermatol (2019)
• Cosmeceuticals for antiaging: a systematic review of safety and efficacy — Arch Dermatol Res (2024)

Vitamin B3 amide

What it does

Three things at once — supports ceramide synthesis and barrier function, reduces sebum, and interferes with the transfer of pigment from melanocytes to surrounding cells. Also anti-inflammatory.

Suits

Almost everyone. Oily skin, congestion, redness, pigmentation, barrier support. Well tolerated across all Fitzpatrick types.

Evidence

Controlled facial studies show reduced hyperpigmentation, red blotchiness and transepidermal water loss with topical niacinamide, and mechanistic reviews attribute this to NAD+ dependent energy metabolism, ceramide synthesis and reduced melanosome transfer. Benefit flattens as concentration rises while irritation reports climb.

Do not layer with

Do not stack two niacinamide serums in one routine.

Note

Chemically compatible with everything, vitamin C included. The old incompatibility claim requires heat and extreme pH not found in finished products. Do not stack two niacinamide serums in one routine.

Flushing in sensitive skin at higher concentrations. Above roughly 10% the additional benefit is modest.

“"Niacinamide is the most versatile thing in the range. It works on oil, on redness and on uneven tone, and almost nobody reacts to it."”

• Niacinamide: a B vitamin that improves aging facial skin appearance — Dermatol Surg (2005)
• Niacinamide — mechanisms of action and its topical use in dermatology — Skin Pharmacol Physiol (2014)
• Mechanistic basis and clinical evidence for nicotinamide in skin ageing and pigmentation — Antioxidants (2021)

Vitamin · antioxidant, tyrosinase inhibitor, collagen cofactor

What it does

Neutralises free radicals, is required for collagen synthesis, and inhibits the enzyme that produces pigment.

Suits

Photoageing, dullness, uneven tone, pigmentation. Morning use.

Evidence

Percutaneous absorption work established that the free acid must be formulated below pH 3.5 to penetrate, with skin levels saturating around 20%. Clinical reviews support photoprotective, collagen and pigment effects, and note that water-based formulations lose activity as ascorbic acid oxidises.

Do not layer with

Copper peptides.

Note

Water-free formulations oxidise far more slowly. A well-made anhydrous product generally outperforms a water-based one at the same percentage. Anhydrous: Water-free formulations oxidise far more slowly. A well-made anhydrous product generally outperforms a water-based one at the same percentage.

Unstable in water with light, heat and oxygen. Needs low pH to penetrate, which can sting. **Store away from light and heat — browning means oxidised.**

“"It's a stated 10% ascorbic acid in an anhydrous base — no water, so it stays stable much longer. Keep it out of the light, and if it goes brown it's past it."”

• Topical L-ascorbic acid: percutaneous absorption studies — Dermatol Surg (2001)
• Topical vitamin C and the skin: mechanisms of action and clinical applications — J Clin Aesthet Dermatol (2017)
• A review of topical vitamin C derivatives and their efficacy — J Cosmet Dermatol (2022)

Plant phenolic antioxidant

What it does

Antioxidant in its own right, and stabilises ascorbic acid, extending how long it stays active.

Suits

Anywhere vitamin C is used.

Evidence

Adding 0.5% ferulic acid to a 15% ascorbic acid plus 1% tocopherol solution improved chemical stability and roughly doubled photoprotection in human skin; a follow-up study confirmed protection against ultraviolet-induced damage including thymine dimer formation.

Well tolerated; it is a stabiliser rather than an active in its own right.

“"Ferulic acid keeps the vitamin C stable and working for longer. Seeing it on a label is a sign the formula was thought about."”

• Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin — J Invest Dermatol (2005)
• A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid protects human skin from UV damage — J Am Acad Dermatol (2008)

Signalling peptides — palmitoyl tripeptide-1, palmitoyl tetrapeptide-7, palmitoyl tripeptide-38

What it does

Short amino acid chains that signal fibroblasts to produce matrix constituents. Effects are gradual and cumulative.

Suits

Photoageing, fine lines, long-term use. Sensitive skin — peptides are among the best-tolerated actives available.

Evidence

Controlled facial studies of palmitoylated signal peptides report modest but measurable wrinkle improvement over 8 to 12 weeks with very low irritation rates. Effect sizes are smaller than retinoids, and the antiaging systematic reviews describe the peptide evidence base as promising but thinner.

No photosensitivity, no significant irritation. Slow — think months.

“"Peptides are signalling molecules. They're gentle, nothing reacts to them, and they work slowly — this is a six-month product, not a six-week one."”

• Topical application of palmitoyl-RGD reduces human facial wrinkle formation — Arch Dermatol Res (2017)
• Cosmeceuticals for antiaging: a systematic review of safety and efficacy — Arch Dermatol Res (2024)

Copper-binding peptide

What it does

Roles in matrix remodelling and wound repair.

Suits

Photoageing. Night use.

Evidence

GHK-Cu has well-described copper-transport and matrix-remodelling activity in laboratory models, and its redox behaviour is the reason it is formulated away from ascorbic acid. Delivery studies note that skin permeation of the intact complex is difficult to demonstrate, so topical clinical evidence remains limited.

Do not layer with

Ascorbic acid. Exfoliating acids.

Note

Concentration varies enormously between products and is often undeclared. Where a percentage is not stated, say so.

**Do not layer with ascorbic acid. Do not layer with exfoliating acids.** The copper participates in redox reactions that degrade both. Separate — copper at night, vitamin C in the morning.

“"Copper peptide goes on at night, and it can't go on with your vitamin C or your acids — the copper reacts with them. So vitamin C in the morning, this one in the evening."”

• Are we ready to measure skin permeation of GHK-Cu tripeptide encapsulated in liposomes? — Molecules (2025)
• Liposomes as carriers of GHK-Cu tripeptide for cosmetic application — Pharmaceutics (2023)

Polydeoxyribonucleotide · low molecular weight DNA fragments, most commonly salmon-derived

What it does

Studied for effects on fibroblast activity and tissue repair, principally in injectable and post-procedural settings. **Topical evidence is considerably thinner than the marketing suggests.**

Suits

Photoageing. Post-procedure support from day zero. Follow treating-practitioner direction.

Evidence

PDRN's adenosine A2A receptor and salvage-pathway mechanisms are described in wound-healing literature, and cell work reports effects on keratinocyte and fibroblast signalling. Almost all of this is preclinical or injectable; controlled topical cosmetic trials are scarce.

Note

Frequently undeclared in topical products. Where a figure is given, 0.5% w/w is equivalent to 5000 ppm.

**Salmon-derived — carries a fish allergen declaration. Ask about seafood allergy before recommending.** Suitable from day zero post-procedure. Academy safety clarification: day-zero use is only under the treating practitioner’s specific direction; do not apply a non-sterile cosmetic to broken or weeping skin.

“"It's a DNA fragment complex. Check the label for a stated concentration — most products in this space won't give you one. One thing first: any allergy to fish or seafood? It's salmon-derived."”

Do not say — Regenerates, repairs, heals, rejuvenates. See Module 8.

• Polydeoxyribonucleotide: a promising biological platform to accelerate impaired skin wound healing — Pharmaceuticals (2021)
• Polydeoxyribonucleotide exerts opposing effects on ERK activity in human keratinocytes and fibroblasts — Mol Med Rep (2023)

Glycosaminoglycan humectant

What it does

Binds a very large amount of water relative to its mass. High molecular weight holds water at the surface; low molecular weight penetrates further.

Suits

Dehydration, all skin types, oily skin included.

Evidence

Formulation research shows molecular weight governs where hyaluronic acid acts — larger fractions form a surface film, smaller fractions penetrate the stratum corneum — and multicentre serum evaluations report improved hydration and smoothness with mixed-weight systems.

In dry air it can draw water outward from the skin. **Apply to damp skin and seal with a moisturiser** — this instruction matters more than the product.

“"Put it on damp skin and put your moisturiser over it. On dry skin with nothing on top it can work against you."”

• Designing topical hyaluronic acid technology — size does matter — J Cosmet Dermatol (2022)
• Multicenter evaluation of a topical hyaluronic acid serum — J Cosmet Dermatol (2022)

Peptide-based humectant

What it does

Binds more water than hyaluronic acid by mass, and forms a surface film that slows evaporation.

Suits

Dehydration, post-procedure, oily skin, layering over or with HA.

Evidence

Keratinocyte and reconstructed-skin work with bacterial poly-gamma-glutamic acid reports increased moisture retention and strengthened barrier markers, and cosmetic ingredient studies describe moisturising and film-forming behaviour distinct from hyaluronic acid.

Note

Works alongside hyaluronic acid rather than instead of it — different molecular behaviour, complementary effect.

Very well tolerated; no photosensitivity.

“"It holds even more water than hyaluronic acid and it leaves a light film that stops it evaporating. It's the one we use after treatments."”

• Poly-gamma-glutamic acid strengthens the skin barrier and improves moisture retention in keratinocytes and a reconstructed skin model — Int J Mol Sci (2025)
• Heterologous poly-gamma-glutamic acid: skin moisturising, brightening and anti-wrinkle effects — Int J Biol Macromol (2024)

Barrier lipids · approximately 50% of the stratum corneum lipid matrix

What it does

Replaces the lipids that hold corneocytes together. The barrier's own primary constituent.

Suits

Compromised barrier, sensitivity, dryness, alongside actives, post-procedure, retinoid nights.

Evidence

Ceramide biology reviews establish their structural role in stratum corneum lipid lamellae, and a controlled study of topical physiological lipids showed a rebalanced ceramide profile and measurably stronger barrier function in adults predisposed to atopic dermatitis.

Note

The barrier needs **ceramides, cholesterol and free fatty acids** — roughly 50 / 25 / 15. A product supplying all three is more physiologically complete than ceramides alone.

No irritation profile of note; the risk here is formulation, not the ingredient.

“"Ceramides are about half of what holds your barrier together, so this is replacing the skin's own material. It's the one you use when everything is stinging."”

• Topical physiological lipids rebalance the stratum corneum ceramide profile and strengthen barrier function — Br J Dermatol (2025)
• Ceramides and skin function — Am J Clin Dermatol (2003)

Sphingoid base · ceramide precursor

What it does

Precursor in ceramide synthesis, with antimicrobial activity.

Suits

Compromised barrier, dryness, blemish-prone skin.

Evidence

Human skin work shows phytosphingosine raises moisture levels by stimulating filaggrin synthesis and degradation to natural moisturising factor, and cutaneous lipid reviews describe the antimicrobial activity of sphingoid bases against skin flora.

Used at low percentages within a formulation; not a standalone treatment.

“"It's a building block the skin uses to make its own ceramides."”

• Phytosphingosine enhances moisture level in the human skin barrier via filaggrin biosynthesis and NMF formation — Arch Dermatol Res (2017)
• The roles of cutaneous lipids in host defense — Biochim Biophys Acta (2014)

Humectant and soothing agent

What it does

Converts to pantothenic acid in the skin. Binds water and calms.

Suits

Sensitivity, post-procedure, alongside retinoids, compromised barrier.

Evidence

Dexpanthenol reviews spanning seven decades of use report improved stratum corneum hydration, reduced transepidermal water loss, faster epidermal recovery after barrier disruption, and reduced erythema and itch, with a very low sensitisation rate.

Rarely sensitising; otherwise unremarkable.

“"Pro-vitamin B5. It holds water and settles the skin down — it's in there to make the rest tolerable."”

• Topical use of dexpanthenol in skin disorders — Am J Clin Dermatol (2002)
• Topical use of dexpanthenol: a 70th anniversary article — J Dermatolog Treat (2017)

Plasmin inhibitor

What it does

Interferes with the plasminogen pathway linking ultraviolet exposure to melanocyte stimulation. Acts further upstream than tyrosinase inhibitors.

Suits

Melasma, post-inflammatory hyperpigmentation, uneven tone. Morning or night.

Evidence

Meta-analyses of randomised trials report significant melasma severity reductions with tranexamic acid across oral, topical and microneedling-assisted routes, with oral use strongest and topical use well tolerated. Photoprotection remains the larger effect in every one of these trials.

Well tolerated, no photosensitivity. **Melasma is doctor-directed** — support a set regimen, do not undertake to clear it.

“"Tranexamic acid works on the pathway that links sun exposure to pigment being made — that's a different point of action from most brightening ingredients. Sunscreen still does more than it does, though."”

• Tranexamic acid as a therapeutic option for melasma: meta-analysis and systematic review of randomised trials (2024)
• Microneedling with topical tranexamic acid for melasma: systematic review and meta-analysis (2024)

Polysaccharide

What it does

Soothing and film-forming. Supports comfort where actives are present.

Suits

Sensitivity, post-procedure, active-heavy routines.

Evidence

Beta-glucan is studied mainly as a film-forming polysaccharide with immunomodulatory and repair-supporting activity in dermal delivery and wound models; controlled cosmetic outcome data is limited and mostly in combination products.

No meaningful irritation profile; supporting ingredient rather than a treatment.

“"It's there to keep the active comfortable."”

• The harnessing potential of carboxymethyl beta glucan: a driver of skin repair (2026)
• Hyaluronic acid / beta-glucan hybrid nanogels for topical dermal delivery targeting skin dendritic cells (2021)

Soothing agent, keratolytic at higher concentrations

What it does

Calms, softens, very well tolerated.

Suits

Sensitivity, dryness, rough texture, alongside actives.

Evidence

Allantoin appears throughout topical formulation literature as a soothing and keratolytic agent, most often studied inside combination products rather than alone, which is why claims should stay at comfort and softening rather than treatment.

Very well tolerated at cosmetic concentrations.

“"A soothing ingredient — it's one of the most reliably well-tolerated things in cosmetic formulation."”

• Efficacy and safety of a topical compound allantoin gel — randomised study (2025)
• Topical use of dexpanthenol and adjunct soothing agents — J Dermatolog Treat (2017)

Mineral UV filters

What it does

Broad spectrum protection across UVA and UVB.

Suits

Sensitive and reactive skin, pigmentation, everyone daily.

Evidence

Reviews of the inorganic filters support broad-spectrum attenuation and a favourable tolerance profile, with no convincing evidence of meaningful systemic absorption of the particulate forms. Application studies consistently show consumers apply far less than the 2 mg/cm2 used to determine SPF, so real-world protection is well below the labelled figure.

Note

Regulatory: A **primary sunscreen** is a therapeutic good requiring ARTG listing. A **tinted base or foundation** containing sunscreen agents is a **secondary sunscreen** and is regulated as a cosmetic. State only the SPF and broad-spectrum claims on the approved label. **Do not call a tinted cosmetic a sunscreen.** Application: Approximately ¼ teaspoon for the face, or the two-finger measure. Reapply every 2 hours of exposure. Ears, hairline, neck, décolletage, hands.

Sunscreens are therapeutic goods in Australia. State only the SPF, broad-spectrum and water-resistance claims that appear on the approved label. Do not extrapolate or paraphrase. Approximately a quarter teaspoon for the face, or the two-finger measure. Reapply every 2 hours of exposure. Ears, hairline, neck, decolletage, hands.

“"Mineral filters, broad spectrum. The number matters less than the amount — most people use about a quarter of what they should. Quarter teaspoon, and show me where you'd stop."”

• A review of inorganic UV filters zinc oxide and titanium dioxide (2019)
• Application of sunscreen — theory and reality (2014)
• Sunburn protection as a function of sunscreen application thickness (2012)

Pigments · visible light attenuation

What it does

Not UV filters. They reduce visible light reaching the skin, which contributes to pigmentation — most notably in Fitzpatrick IV and above.

Suits

Melasma, post-inflammatory hyperpigmentation, any pigmentation concern.

Evidence

Visible light induces persistent pigmentation in darker phototypes, and reviews of tinted sunscreens show iron oxide pigments attenuate that waveband where organic and mineral UV filters largely do not. Comparative work in melasma favours tinted formulations over untinted ones.

Note

This is why a **tinted** sunscreen is preferred where pigmentation is the concern. An untinted product does not offer visible-light attenuation.

Cosmetic shade matching limits acceptability; it does not replace UV filtering.

“"The tint isn't cosmetic. Iron oxides reduce the visible light reaching your skin, and visible light contributes to pigmentation — so for pigment concerns, tinted does something untinted can't."”

• Photoprotection beyond ultraviolet radiation: a review of tinted sunscreens (2021)
• Guide to tinted sunscreens in skin of color (2024)

22 free-form L-amino acids · nine essential, thirteen non-essential

What it does

Supplies amino acids already in their absorbable form, so no digestion of whole protein is needed. Plasma amino acid levels rise sooner and higher than after an equivalent amount of intact protein.

Suits

People with poor appetite, low protein intake, compromised digestion, or intolerance to dairy and plant protein powders. A nutritional top-up, never a protein replacement.

Evidence

A double-blind randomised trial in young adults found free amino acids were absorbed faster with greater postprandial availability than intact protein, yet muscle protein synthesis rates did not differ. A later trial confirmed the improved exogenous availability. Position papers support higher protein intakes in older adults and even distribution across the day.

The blend contains branched-chain amino acids, so the label warning applies: BCAA supplements have been linked with lung failure and higher death rates in amyotrophic lateral sclerosis and should not be used by anyone with ALS. Refer pregnancy, breastfeeding, children, kidney or liver disease, phenylketonuria and other inherited metabolic disorders, protein-restricted diets, and anyone raising a medicine interaction.

“It's amino acids in the form the body absorbs directly, so it's gentle on digestion. It tops up intake — it doesn't replace eating enough protein.”

Do not say — Anything about healing skin, treating a condition, or building muscle. Faster absorption is not the same as a better outcome.

• Ingestion of free amino acids versus an equivalent amount of intact protein — absorption and muscle protein synthesis (RCT)
• Free amino acids improve exogenous amino acid availability versus intact protein
• Optimal dietary protein intake in older people — position paper
• Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?

L-leucine, L-valine, L-isoleucine

What it does

Leucine is the strongest single signal for muscle protein synthesis. Valine and isoleucine share the same transport and metabolic pathway.

Suits

Recovery contexts where total essential amino acid intake is already adequate.

Evidence

Leucine-dose work shows a high proportion of leucine is needed for optimal stimulation of synthesis, but review evidence concludes BCAAs alone are insufficient — whole-body benefit tracks the complete essential set, not leucine in isolation.

Do not use in amyotrophic lateral sclerosis: the label warning about lung failure and increased mortality is specific and must be repeated unsoftened. Refer anyone on a protein-restricted diet or with inherited metabolic disease.

“Leucine is the trigger amino acid, but on its own it does less than the full set — which is why a complete blend is used rather than BCAAs alone.”

• A high proportion of leucine is required for optimal stimulation of muscle protein synthesis
• Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?
• Branched-chain amino acids in a model of amyotrophic lateral sclerosis

Naturally occurring polyamine · wheat germ, aged cheese, soy, mushrooms

What it does

Induces autophagy, the regulated recycling of damaged proteins and organelles. Tissue polyamine levels decline with age.

Suits

Longevity-category education only. Not a skin treatment and not part of a topical routine.

Evidence

Lifespan extension is consistent across yeast, flies, worms and mice, with autophagy-dependent cardiac benefits in mice. In humans a prospective cohort linked higher dietary intake to lower all-cause mortality — an association only — while a 12-month randomised trial in older adults with subjective cognitive decline found no memory benefit versus placebo. A smaller three-month study reported positive signals.

Note

Strong animal data plus a cohort association plus a null trial is exactly where this ingredient sits today.

Long-term human safety data are limited. Refer pregnancy, breastfeeding, children, any current or past cancer (autophagy interacts with tumour biology), kidney or liver disease, and anyone already taking polyamine or NAD+ precursor supplements.

“Spermidine switches on the cell's recycling process in laboratory work. The human trials so far measure markers and one cognition study found no benefit — so that's how I'll describe it.”

Do not say — That it slows ageing, protects the heart, or improves skin. No human trial supports that.

• Spermidine in health and disease — Science review
• Cardioprotection and lifespan extension by the natural polyamine spermidine
• Higher spermidine intake is linked to lower mortality — prospective population study
• Spermidine supplementation and cognition in older adults — randomised clinical trial
• Spermidine in older adults with dementia — 3-month study

NAD+ precursor · nucleotide

What it does

Raises NAD+, a coenzyme required for energy metabolism and used as a substrate by sirtuins and PARP enzymes. NAD+ availability falls with age; NAD+ itself is not usefully absorbed intact, so a precursor is used.

Suits

Longevity-category education. Distinct from topical niacinamide — do not conflate the two.

Evidence

A randomised placebo-controlled trial in healthy middle-aged adults found NMN raised blood NAD+ and was well tolerated over 60 days, with modest functional secondary measures. A trial in amateur runners reported improved aerobic capacity alongside training; another examined arterial stiffness after long-term use. No human trial has shown slower ageing.

Refer pregnancy, breastfeeding, children, cancer history, kidney or liver disease, and anyone already taking nicotinamide riboside or another NAD+ precursor. Report what was measured, in whom, and for how long.

“It raises a coenzyme called NAD+ that declines with age. The trials measured blood levels and, in runners, aerobic capacity — that's the honest limit of it.”

Do not say — That it reverses or slows ageing, or that it does what topical niacinamide does for the barrier.

• NAD+ intermediates: the biology and therapeutic potential of NMN and NR
• Efficacy and safety of β-nicotinamide mononucleotide in healthy middle-aged adults (RCT)
• NMN supplementation enhances aerobic capacity in amateur runners (randomised trial)
• NAD metabolism and arterial stiffness after long-term NMN supplementation

Phycobiliprotein pigment from Arthrospira platensis

What it does

A coloured protein pigment with antioxidant and immunomodulatory activity described in the literature.

Suits

Formulation and colour context in ingestible blends.

Evidence

Reviews of Spirulina describe antioxidant, immunomodulatory and anti-inflammatory activity, and a further review covers brain-health evidence. Most of this work is in vitro or in animal models rather than human clinical trials.

Ask about any previous reaction to spirulina or algae. Refer anyone with autoimmune disease or on immunosuppressive therapy, given the immunomodulatory activity, and refer pregnancy, breastfeeding and children.

“It's a pigment protein from spirulina with antioxidant activity described mostly in laboratory studies — I'd keep it at that.”

• Antioxidant, immunomodulatory and anti-inflammatory activities of Spirulina — overview
• Beneficial effects of Spirulina consumption on brain health — review

Proteinogenic amino acid · most abundant residue in collagen

What it does

Supplies the dominant amino acid of collagen alongside proline, and contributes to glutathione synthesis.

Suits

Amino acid intake context. Not evidence that swallowing glycine remodels skin.

Evidence

Glycine and proline dominate collagen's amino acid composition, and cysteine-containing intake supports glutathione. Benefit from amino acid intake tracks total protein adequacy rather than any single residue.

Refer protein- or amino-acid-restricted diets and inherited metabolic disorders.

“Glycine is the building block collagen uses most. Supplying it supports intake — it doesn't direct the body to build collagen in one place.”

Do not say — That taking glycine builds collagen in the skin.

• Optimal dietary protein intake in older people — position paper
• Dietary protein distribution positively influences 24-h muscle protein synthesis