Good points @sammmy I have to agree with you..... reversing some epigenetic markers might address certain cellular and molecular aspects of aging, but it might not fully reverse the overall physiological changes that occur with age.Reversed epigenetic markers do not manifest as reversed aging. Take Bryan Johnson - his epigenetic age is 20 years, yet he doesn't look that young.
The primary effect in this study on thymus is coming from HGH - as they point out in the discussion section, that was established by previous studies. They added metformin to suppress insulin secretion caused by increased IGF-1 by the HGH.
The vitamin D might have reduced inflammation - it is immunosuppressive.
The high daily dose Zinc may be toxic over the long run and may have caused the increased liver enzyme.
The role of DHEA is unclear - they tried to suppress insulin by DHEA alone and apparently it didn't work so they added the metformin. Why is then DHEA still in the final cocktail?
The authors are also shareholders in some bio startup and will probably try to patent the "magical cocktail" as some hyped up age reversal "proprietary formula".