How can one know which brand of herbal supplements is best and most credible?

I spend alot of money buying alot of herbal and nutritional supplements, but lately I've been wondering how one can know which supplements truly contain the ingredients that they claim in the amounts that they claim, and whether they are manufactured with quality standards, etc. Since they aren't regulated, how can one know for sure….

How can I increase lower body flexibility to be able to do the splits while also gaining muscle mass?

I would like to gain more lower body flexibility to be able to do the splits but also workout my lower body too to gain muscle mass. What stretches are effective and does increasing muscle mass make it harder ie. do your muscles become too ‘tight’ to become flexible. I can do the splits on…