Which alpha hydroxy acid (AHA) penetrates the epidermis most effectively?

• A. Glycolic acid
• B. Lactic acid
• C. Citric acid
• D. Malic acid

Answer: (A)

Verified step by step guidance

1. Understand the concept of alpha hydroxy acids (AHAs): AHAs are a group of acids commonly used in skincare to exfoliate the skin. They work by loosening the bonds between dead skin cells, promoting cell turnover. Their effectiveness in penetrating the epidermis depends on molecular size and chemical properties.
2. Analyze molecular size: Smaller molecules penetrate the skin more effectively. Glycolic acid has the smallest molecular size among the listed AHAs, making it more efficient at penetrating the epidermis compared to lactic acid, citric acid, and malic acid.
3. Consider chemical structure: Glycolic acid has a simple structure with fewer functional groups, which contributes to its ability to penetrate the skin more deeply. Larger or more complex molecules, like citric acid and malic acid, may face more resistance due to their size and structure.
4. Evaluate pH and solubility: AHAs work best at a lower pH, where they remain in their active form. Glycolic acid is highly effective at lower pH levels, enhancing its ability to penetrate the epidermis compared to other AHAs.
5. Conclude based on evidence: Based on molecular size, chemical structure, and pH effectiveness, glycolic acid is the AHA that penetrates the epidermis most effectively.