Which substance cannot be absorbed by the skin?

While it's accurate that water cannot be absorbed by the skin in the same way as oil or other lipid-soluble substances, it's important to clarify the nature of skin absorption. The skin serves as a barrier primarily due to its outermost layer, the stratum corneum, which is composed of dead skin cells and lipids. This barrier effectively prevents the passage of larger molecules and certain aqueous substances.

Wheat germ oil, vitamin E, and retinol are all lipophilic (oil-soluble) or have the ability to penetrate the skin to some degree. Wheat germ oil contains fatty acids that can easily integrate into the skin's lipid matrix. Vitamin E, being an antioxidant and fat-soluble vitamin, is readily absorbed and offers moisturizing benefits. Retinol, a derivative of vitamin A, is well-documented for its ability to penetrate the skin layers and promote skin renewal and rejuvenation.

In contrast, water lacks the necessary lipophilic properties that would allow it to permeate through the skin effectively, making it less absorbable in the context of topical application. Instead, while water can hydrate the outer layers of the skin temporarily, it does not penetrate deeply. Rather, it typically evaporates or is removed through the skin’s barrier without