this is more an art than a science.
if you are getting older, (It's that simple) you have a imbalance, can be a lack of antio., heavy metals poison, excessive work or sport, body obstructions, physical, psychic and astral damage, industrial or radioactivity poison, EMF, chemtrails... and only Lucifer known how many endless and continuous attacks your body suffers
people clean their cars, change tubes, pipes, filters... and do nothing in their bodies
exist a lot of methods, procedures... you need to investigate and make choices using your intuitive intelligence, so a search motor, your local or national library are your friends. of course just do not expect to find it by searching in places like google, you need to search in databases, books, internet invisible...
what are antioxi.? spices, vit C, black or blue berries like elderberries, blueberries, (for exemple with blueberries you can see the effect because your eye vision is improved, this is from the "night bomber guys in WW2"), CDS, Hydrocotyle vulgaris put more oxygen in your cells, etc, etc, etc. start reading the old post and you can find useful info.
www.rice.edu/~jenky/sports/antiox.html
www.care2.com/greenliving/5-spices-that-are-the-most-powerful-antioxidants.html
www.realfarmacy.com/kitchen-table-strategies-effectively-optimize-turmeric-maximum-bioavailability-therapeutic-potency/
and so on, good luck!