Disavow the bad backlinks via webmaster console, you'll notice a huge penalty for letting these bad sites link to you without disavowing them. It looks like (to Google) you're buying backlinks, and in this case ones on sites that are slammed by the latest updates. Try this on a few of the worst offenders and you'll see a noticable difference.
In your space you have the most aggressive blackhat seo actors (supplements) looking at you as the bad guy for exposing them, I wouldn't be surprised if you discover a ton of bad backlinks from domains that have a terrible reputation. Source: lost over 100,000 unique Google visits per day because of a malicious competitor putting unsolicited backlinks to our domain without our knowing and it took months before it came back.