Unfortunately what you have stated is true in some cases. Most often found though in refined, processed, or chemically produced vitamins, minerals, etc.
That is only one BIG thing wrong with these tests and subsequent articles... they NEVER tell you WHAT they used and how it was processed or sourced. Herbs live in cycles and harvested at incorrect times and/or grown in less than ideal conditions or out of their native environment and efficacy WILL be affected. These works NEVER tell us this valuable and MISSING information.
As a people, educated to believe in the "better life through chemistry" mentality it is hard to give up our search for that magic cure all and gives bad, greedy people a foot hold into the alternative health arena where they laugh all the way to the bank.
In my opinion, I believe studies are a huge waste of time and money. History and tens of thousands of years of use of foods, herbs and physical modalities, have shown what works and what does not.
I should have been tutored by great grandma and grandma before they passed away, they knew things that are now lost to me and both lived well into their 90's. Their parents lived to their early 100s and my parents will be lucky to see 80... average life expectancy is falling rapidly (my brother and sisters will be lucky to see 60 they are so sick now) due to a “better life through chemistry” which is being revealed as the lie IT IS.