Telomeres are bits of DNA at the ends of each chromosome, and protect the chromosome during cell division. Over time, the bits of DNA get shorter, and it’s exacerbated by things like sun exposure. When the telomere is too short, it blocks cell division, and leads to aging of your cells, and thus to various ailments and diseases.

The “The Telomere Effect” was written by two authors, one of whom received the Nobel prize for her work on telomeres, so it’s quite authoritative.

Their view is that
(a) the length of the telomeres has a direct effect on how we age,
(b) shortening of telomeres is contributory to heart disease, COPD, cancer, dementia and other ailments.
(c) there are aspects of lifestyle, attitude and diet that are associated with maintaining longer telomeres, and thus longer healthy life, including:
* keep a positive state of mind, avoid pessimism, take regular exercise, keep yourself fit, get at least 7 hours sleep, little or no belly fat, avoid toxins and chemicals,
* also, in terms of diet: minimal sugar and refined carbs, eating less animal and dairy fat, occasional coffees (they are good!), avoid grilled/charred food, buy organic if possible, get an adequate amount of Omega 3.

For the full story, and the recommendations in detail, you’ll need to read the book yourself, but meantime, the recommendations seem to be more or less in line with those in other books, also from authoritative authors.