The 500-Dalton Rule: Which Vitamin Patch Ingredients Actually Work?
Your skin blocks most molecules heavier than about 500 Daltons - so an ingredient can look impressive on a patch’s label while being far too big to actually absorb. The 500-Dalton rule is the quick test for which vitamin patch ingredients genuinely get through your skin, and which (collagen, B12, hyaluronic acid) can’t.
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What is the 500-Dalton rule?
A Dalton (Da) measures the weight of a molecule. The 500-Dalton rule is a rule of thumb, first set out in dermatology research, that molecules above roughly 500 Daltons struggle to cross the skin’s outer barrier (the stratum corneum) in meaningful amounts. Below 500, absorption becomes realistic; above it, the door is mostly shut. It’s why we design every What Supp Co patch with it front of mind.
Why does molecular size matter for a vitamin patch?
The whole promise of a patch is transdermal delivery - ingredients absorbed through the skin over time, rather than swallowed. That’s genuinely useful: it bypasses the digestive system and releases slowly rather than in one hit.
But “on the skin” and “through the skin” are two very different things. An ingredient that’s too large to cross the barrier can sit in the patch looking impressive on the ingredients list while never actually getting anywhere. So when you’re choosing a patch, the real question isn’t “what’s in it?” - it’s “can what’s in it actually get through?”
Which common patch ingredients fit through skin?
Here’s the approximate molecular weight of ingredients you’ll see across the wearable-wellness category. Anything comfortably under ~500 Da is a sensible candidate for a patch. We’ve rounded to keep it readable.
| Ingredient | Approx. molecular weight (Da) | Under the 500 rule? |
|---|---|---|
| Caffeine | 194 | Yes |
| L-theanine | 174 | Yes |
| Vitamin C (ascorbic acid) | 176 | Yes |
| Melatonin | 232 | Yes |
| Valerenic acid (from valerian) | 234 | Yes |
| Resveratrol | 228 | Yes |
| Creatine | 131 | Yes |
| Niacinamide (B3) | 122 | Yes |
| NMN | 334 | Yes |
| Berberine | 336 | Yes |
| Vitamin D3 | 384 | Yes (borderline) |
| Withanolides (from ashwagandha) | ~470 | Yes (borderline) |
| NAD+ | 663 | No - too large |
| Vitamin B12 (cyanocobalamin) | 1,355 | No - too large |
| Collagen peptides | ~2,000-5,000+ | No - far too large |
| Hyaluronic acid | up to 1,000,000+ | No - vastly too large |
The pattern is clear: many of the botanicals, vitamins and precursors people want do fit. But some of the buzziest names in wellness - collagen, NAD+, B12, hyaluronic acid - are simply too big to cross the skin barrier intact. That doesn’t make them bad ingredients. It just means a patch is the wrong delivery method for them.
So how do brands sell “collagen patches” or “NAD+ patches”?
This is where it pays to read past the product name. There are two things a brand can be doing:
First, and fairly: using precursors. Your body makes its own collagen from smaller building blocks - amino acids, vitamin C - which are small enough to absorb. A patch can’t deliver collagen, but it can deliver some of the raw materials. That’s a legitimate approach, as long as the brand is upfront that the patch contains the building blocks, not the finished ingredient it’s named after.
Second, and less fairly: naming a patch after an ingredient it doesn’t actually contain, or one that couldn’t get through even if it did - and letting the name do the selling while the small print quietly tells a different story.
Neither is illegal. But you deserve to know which one you’re buying. Which brings us to the only checklist you need.
How to check a vitamin patch actually works: 4 questions
- Does the patch contain what the name promises? Read the ingredients list. If a “collagen patch” doesn’t list collagen, or lists only “supports collagen production,” the name is doing work the formula isn’t.
- Are the active ingredients under ~500 Daltons? Use the table above. If the headline ingredient is far heavier, ask how it’s meant to get through your skin.
- How is the patch made - and where? Construction matters (more layers and an occlusive, waterproof seal help hold actives against the skin), and so does knowing who made it. A brand confident in its manufacturing will tell you where it happens. For more on this, see do vitamin patches work.
- How long does it release for? A steady release over many hours beats a quick fade. Check the wear time.
The What Supp Co approach
We built our patches around this rule rather than around a trend list. Every active in our range is chosen to be small enough to absorb, held against the skin by our four-layer, occlusive, waterproof Patchtech™ for a steady 12-hour release, and made in the UK. We’d rather name a patch for how it’s meant to make you feel - and put ingredients in it that can actually get to work - than borrow a buzzword that can’t get past your skin.
References
The 500-Dalton rule was first set out in: Bos JD, Meinardi MMHM. “The 500 Dalton rule for the skin penetration of chemical compounds and drugs.” Experimental Dermatology, 2000;9(3):165-169. Molecular weights quoted are standard reference values (PubChem). Collagen peptides and hyaluronic acid are polymers whose molecular weight varies by product, so their figures are given as ranges.
Frequently asked questions
What is the 500-Dalton rule in simple terms?
It’s a guideline that says molecules heavier than about 500 Daltons generally can’t pass through the skin’s outer barrier. For a patch, it’s the difference between an ingredient that absorbs and one that just sits there.
Can you really absorb vitamins through the skin?
Yes - if the molecules are small enough. Many vitamins and botanicals are well under 500 Daltons and are sensible candidates for transdermal delivery. Some, like vitamin B12 and collagen, are too large.
Do collagen patches work?
A patch can’t deliver collagen itself - the molecule is far too big to cross the skin. Some “collagen” patches instead supply smaller building blocks like amino acids and vitamin C. If that’s what you’re after, check the ingredients list says so plainly.
Are NAD+ patches effective?
NAD+ is around 663 Daltons, above the ~500 threshold for easy skin absorption. Smaller precursors such as NMN (around 334 Daltons) fit the rule more comfortably, which is worth knowing when you compare products.
How long should a vitamin patch be worn?
It depends on the patch, but a longer, steady release is generally better than a quick one. Ours are designed for 12 hours. Always follow the pack instructions.
Is a food supplement patch a medicine?
No. Vitamin patches are food supplements, not medicines, and aren’t intended to diagnose, treat, cure or prevent any disease. They’re best used alongside a balanced diet, not as a replacement for one.
This article is for general information and isn’t a substitute for medical advice. As with any supplement, if you’re pregnant, breastfeeding, taking medication or have a medical condition, speak to your GP or pharmacist before starting. Food supplements should not replace a varied, balanced diet or a healthy lifestyle.
