Received: 22 August 2020
Accepted: 10 December 2020
First Online: 14 February 2021
Compliance with ethical standards
: Keiichiro Ishibashi, Michiya Kobayashi, and Hideyuki Ishida received a research grant from Yakult Co., Ltd., and Chugai Pharmaceutical Co., Ltd. Emiko Takeshita and Masatoshi Oya received a research grant from Yakult Co., Ltd., and Hiroshi Maekawa received a research grant from Chugai Pharmaceutical Co., Ltd. The other authors have no conflicts of interest to declare.