What is the primary component responsible for natural hair color?

The primary component responsible for natural hair color is melanin, which is located in the cortex of the hair strand. Melanin is a pigment produced by melanocytes, and it determines the color of the hair. There are several types of melanin that contribute to a range of hair colors, including eumelanin (which is responsible for black and brown hues) and pheomelanin (which gives rise to red and yellow tones).

The cortex, which is the thickest layer of the hair shaft, plays a crucial role in the hair's structural integrity and color. Because melanin is concentrated in this layer, the amount and type of melanin present directly influence the hair's appearance.

The other components mentioned do not directly influence hair color. Keratin is a protein found in various parts of the hair, but it is not responsible for its color. The cuticle serves as a protective layer and does not contain pigments. Cholesterol, while present in the hair shaft as part of the lipid composition, is also not related to hair color. Therefore, recognizing melanin in the cortex as the key factor in determining hair color is fundamental in understanding hair biology.