LEVEL 3
How to Choose a Serum
You often see claims like "Contains Niacinamide" or "Contains Peptides" on serums. However, what matters is not whether an ingredient is included, but whether it is formulated at a concentration proven to be effective.
For major active ingredients, research has established approximate concentrations at which efficacy has been confirmed.
Niacinamide: 2-5% (wrinkle improvement, brightening)
Retinol: 0.01-0.1% (high concentrations carry irritation risk; too low is ineffective)
Vitamin C Derivative (APPS): 1-3% (some products have low practical efficacy due to stability issues)
Peptides: varies by type (0.001-2%) (significant variation in raw material grade purity)
The problem is that most brands do not disclose their formulation concentrations.
Strictly speaking, "Contains XX" can be claimed even at 0.0001%. Consumers can only assess the presence or absence of an ingredient -- not its quantity. This is like buying food without a nutrition facts label.
So how do you evaluate products from brands that do not disclose? You could cross-reference the 1% line position with the raw material manufacturer's recommended concentration, but this is impractical for most consumers.
Choose brands that disclose their formulation ratios. This is one of the most rational selection criteria available.
KAIAN develops skincare products based on scientific evidence.
Feel free to ask questions about ingredients and formulations.
