Effects of ingesting milk fermented by Lactococcus lactis H61 on skin health in young women: A randomized double-blind study

We conducted a randomized double-blind trial to evaluate the effects of fermented milk produced using only Lactococcus lactis strain H61 as a starter bacterium (H61-fermented milk) on the general health and various skin properties of young women. Healthy female volunteers (n = 23; age = 19–21 r) received H61-fermented milk (10¹⁰ cfu of strain H61/d) or conventional yogurt (10¹⁰ cfu of both Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus per day), as a reference food, daily for 4 wk. Before and at the end of 4 wk, blood samples were taken, and skin hydration (inner forearms and cheek) and melanin content, elasticity, and sebum content (cheek only) were measured. Skin hydration at the inner forearm was higher at wk 4 than at wk 0 in both groups. Sebum content in cheek rose significantly after intervention in the H61-fermented milk group, but not the conventional yogurt group. Other skin parameters did not differ in either group. Serum analysis showed that total protein concentration and platelet count were elevated and reactive oxygen species decreased in both groups after the intervention. Although H61-fermented milk and conventional yogurt had similar effects on skin status and some blood characteristics of participants, an increase of sebum content in cheek is preferable to H61-fermented milk. As skin lipids contribute to maintaining the skin barrier, H61-fermented milk would provide beneficial effects on skin for young women.