Here is a quick summary of some good health advice I have read, which is particularly relevant for older people.
Cognitive decline can be halted, it is hypothesised, by a combination of omega 3, from oily fish or capsules, and B vitamins:
https://www.naturalnews.com/2017-12-10-halt-mental-decline-with-omega-3s-and-b-vitamins.html
https://www.iospress.nl/ios_news/omega-3-levels-affect-whether-b-vitamins-can-slow-brains-decline/
Coffee can reduce the risk of mortality from all causes and increase longevity:
https://www.theatlantic.com/health/archive/2012/11/the-case-for-drinking-as-much-coffee-as-you-like/265693/
http://edition.cnn.com/2017/07/10/health/coffee-leads-to-longer-life-studies-reaffirm/index.html
Dark chocolate and olive oil improve cardiovascular health:
https://www.escardio.org/The-ESC/Press-Office/Press-releases/Dark-chocolate-with-olive-oil-associated-with-improved-cardiovascular-risk-profile
If you cannot find olive oil enriched chocolate then I suppose one could wash down some sugar free 90 percent cocoa chocolate, with a spoonful of olive oil. It is not so bad. As well, olive oil is hypothesised to have anti-cancer benefits:
https://www.naturalnews.com/049132_olive_oil_cancer_antioxidant.html
The general picture that emerges from reading these health articles is that most of the things that help cardiovascular health, also help prevent cancer. Many herbs have an impact. For example, there is thought that cayenne pepper may help with various heart issues:
https://www.naturalhealth365.com/cayenne-pepper-stop-heart-attack-1145.html
Without the vast big medicine superstructure which we now have, in the future people may have to turn to folk remedies. This is what it may be like in a few more years of social decay:
http://collapse.news/2017-12-09-collapsing-venezuelas-chronic-shortages-have-led-to-creation-of-medical-flea-markets.html
In the future, after the present crop of pests die out, the main threat will be from disease, as it was in pre-modern times:
https://survivalblog.com/dont-prey-l-h/#more-50650
See, I have lost my faith in humanity, following the same sex vote, and the failure to protect religious freedoms. Can you imagine what it will be like for the sub-urbans, when the lights go out, and do not come back on again? Someone wrote about that, but my memory is fading. (Editor: the article is by Brian Simpson, “Lights Out for America … and Australia,” 7 December 2017)