Sebum Output as a Factor Contributing to the Size of Facial Pores

Results

Mean Sebum Output Level and Pore Size

The mean sebum output levels were 152·0 µg cm^-2 in males and 102·9 µg cm^-2 in females (Fig. 2A). The sebum output level was significantly higher in males than in females (P < 0·05). The pore sizes were measured in the exact locations where the sebum output levels were measured. The mean pore sizes were 0·068 mm² in males and 0·090 mm² in females (Fig. 2B). The mean pore size was significantly larger in females than in males (P < 0·05).

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Figure 2.

(A) Mean sebum output level (µg cm^-2) and (B) mean pore size (mm²). The sebum output level was significantly higher in males than in females and pore size was significantly larger in females than in males (P < 0·05, 95% confidence interval).

Changes in Sebum Output Level and Pore Size With Increased Age

While sebum output levels increased slightly in proportion to the age (P < 0·05) (Fig. 3A), pore sizes were reversely proportionate to the age (Fig. 3B). However, the latter was not statistically significant.

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Figure 3.

Changes in (A) sebum output level and (B) pore size with increased age. While sebum output level increased slightly with age, pore size decreased with age. However, results were not statistically significant.

Factors Affecting Pore Size: Sebum Output Level, Sex, Age and Menstrual Cycle

When multiple linear regression analysis was used to analyse the data, the increase in pore size correlated with an increase in sebum output level, sex and age (r = 0·45, P < 0·01) ( Table 1 , Fig. 4). Among the independent variables, sebum output level correlated most significantly with the pore size. In comparing male and female participants, males had higher correlation between sebum output level and pore size (males: r = 0·47, females: r = 0·38). Thus, we analysed additional factors such as the menstrual cycle and prior acne severity that may affect pore size in female participants. Among the additional factors, phases of the menstrual cycle showed significant correlation (P = 0·007). Multiple linear regression analysis demonstrated higher correlation when phases of the menstrual cycle were added as an independent variable (r = 0·38 r = 0·43). However, acne severity was not significantly associated with pore size in either males or females. We further analysed the difference of pore size and sebum output levels according to the phase of the menstrual cycle. The menstrual cycle was divided into follicular, ovulation and luteal phases. By using ANOVA [multiple comparison method; least significant difference (LSD)], sebum output levels were found to be significantly higher during the ovulation phase than in the follicular or luteal phase (P = 0·001) (Fig. 5A). In addition, pore sizes were also significantly increased in the ovulation phase compared with the follicular phase (P = 0·008) (Fig. 5B).

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Figure 4.

Relationship between pore size and sebum output level. Increase in pore size correlated with increase in sebum output level and also with sex and age (r = 0·45, P < 0·01).

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Figure 5.

Changes in (A) sebum output level and (B) pore size during menstrual cycle. Sebum output level was significantly higher during ovulation phase than in follicular or luteal phase (P = 0·001). Pore sizes were significantly increased in the ovulation phase compared with the follicular phase (P = 0·008).

The British Journal of Dermatology. 2006;155(5):890-894. © 2006  Blackwell Publishing