Understanding immunity
changes how you understand your health.

Your immune system ages along with you — fewer fresh “naïve” T cells ready for new threats, more worn-out ones that mostly stoke inflammation. In nearly 6,000 older adults, those reporting more stress, trauma or discrimination had exactly this older-looking immune profile, which is tied to higher risk of infections, cancer and weaker vaccine responses. Encouragingly, the stress link shrank once diet and exercise were accounted for. The practical point: you can’t erase stress, but you can blunt its toll on your immune system — protect sleep, keep moving, eat well, and lean on your relationships; those buffers are partly why the same stress ages some people faster than others.

Colorectal cancer used to be seen as an older person’s disease, but that’s changing fast: the share of cases in people under 55 nearly doubled between 1995 and 2019, and death rates in the under-50s have been creeping up. Because so many early cases occur at 45– 49, guidelines now recommend starting screening at 45 for people at average risk. The practical point: if you’re 45 or older, get screened — a colonoscopy or a simple at-home stool test can catch it early or even prevent it; and at any age, don’t ignore warning signs like blood in the stool, a lasting change in bowel habits, or unexplained weight loss — get them checked.

A large systematic review and dose-response meta-analysis combined evidence from 63 prospective studies and found that people who ate more nuts had lower risks of cardiovascular disease and death. Compared with the lowest intake, the highest intake was associated with about 26% lower cardiovascular mortality and 23% lower risk of death from any cause. The findings support nuts as part of a heart-healthy diet, although the studies show an association rather than proving that nuts themselves prevent death.