significant reduction of body odor in older people with a ph 4.0 emulsion

The impact of increasing age on body odor has become an important issue as our understanding of underlying skin changes in older people has increased. Therefore, cosmetic skin products especially for the needs of the elderly are of growing importance. This randomized single-blind crossover study assessed the deodorizing efficacy of two cosmetic products with different pH values on the age-specific odor of an elderly female subject panel (≥60 years). The two test products, adjusted to pH 4.0 and pH 5.8 were applied to the axillae once daily for three consecutive days after standardized washing of the axillae. The untreated axilla was used as a control. Six odor judges evaluated the efficacy of both products. Additionally, bactericidal and fungicidal activity was investigated with in vitro microbiologic tests. The pH 4.0 water in oil (W/O) emulsion significantly reduced axillary malodor in 44 elderly subjects at 8 and 24 h after treatment, compared with controls (untreated axillae) (p < 0.001 after 8 and 24 h), whereas pH 5.8 emulsion had no effect (p = 0.441 after 8 h; p = 0.425 after 24 h). Moreover, the pH 4.0 emulsion reduced axillary malodor at 8 and 24 h after treatment, compared with the pH 5.8 emulsion just narrowly missing statistical significance (p = 0.078 after 8 h; p = 0.053 after 24 h). Microbiologic in vitro tests showed that the pH 4.0 emulsion reduced the levels of odor-producing bacteria S. epidermidis and C. minutissimum after 1 h (2.98 log and 4.25 log). After 24 h, levels of S. aureus (>5.50 log), P. acnes (>5.30 log) and E. coli (>5.46 log) were further reduced whereas no effect was observed for pH 5.8. A pH 4.0 emulsion significantly reduced axillary malodor for up to 24 h after application in females aged at least 60 years. This reduction in malodor is very likely due to a reduction of odor-producing bacteria.