I'm a skeptical sort by nature and am thus far unconvinced that the ingestion of herbs, vitamins or other botanicals has a significant impact on skin or hair aging.
But I'd be happy to be proven wrong.
What is your best scientific evidence that convinces you that "beauty from within" products are effective?
This paper is a review of Vitamin C and it's effect on skin.
If you dig deep into it, you'll see that no one has done a double blind, controlled study comparing Vitamin C supplements to a placebo. This would be such a simple test to do which suggests to me that it has been done & the results were not compelling.
What do you think?