I read 2 interesting articles recently on our sense of smell:
https://clicks.aweber.com/y/ct/?l=CV_1u&m=knlx2BiQEMicE4Y&b=7UM2EJKzQYEVIpi3tc62UA
https://clicks.aweber.com/y/ct/?l=CV_1u&m=knlx2BiQEMicE4Y&b=0jrpr4We8OwDXjvLMFlYRg
Both of the articles link a change for the worse in your sense of smell to ill health and an increased risk of mortality.
The first article posits 2 theories for why this may be so:
1. Mice missing a gene (recombinant activating gene - RAG) involved with your immune system (meaning they lack a working immune system) also had a weakened sense of smell. The theory is the RAG gene is also responsible for protecting the cells linked to smell.
2. Another theory posed by Andrew Davis an immunologist from the University of Manchester, is that everything links back to the strength of your microbiome (gut bacteria).
Me personally - I think theory number 2 is spot on. When I used to drink Kefir my sense of smell used to go through the roof for the first few days afterwards.
So look after your gut bacteria and all else follows! I'm currently reading a great book on this and will share some findings with you.