Evidence is consistent, with known limits.
The main Cochrane review says exercise eases chronic back pain, at moderate certainty, and most clearly in the first few months. For a new episode the answer is different, and which exercise is best is less certain still.
Fifteen randomised trials: cutting saturated fat probably cut cardiovascular events by about 17%, with little or no difference to how long people lived. Twenty-one cohort studies found no significant link. A 2026 review says how much it helps depends on your risk.
The US reference standard is 22,379 measured tests. Three things move your percentile before you train: which machine, which edition of the chart, and whether anyone measured you at all.
A 2018 review of 99 studies set the common recovery methods side by side, and massage came first for soreness and fatigue. Whether it makes you any stronger or faster afterwards is unproven, which is not the same as disproven.
In pooled trials, cold water eased soreness for up to four days after muscle-damaging exercise. It has not clearly beaten warm water, and used straight after lifting it can blunt muscle growth, by an amount that is small and not yet certain.
In pooled trials it helps people keep going a little longer in hard efforts of about one to ten minutes: a median gain of 2.85% in a 2012 review. Pooled, 20 trials found no change in body composition.
In adults with type 2 diabetes, 10-minute walks after each meal shrank the rise in blood sugar after meals by 12%, and after dinner by 22%. The week's average did not move.
In pooled trials melatonin shortens the time to fall asleep by a few minutes: about seven in a 2013 review, about two in adults alone in 2022. Europe licenses a 2 mg slow-release tablet for people 55 and over; the FDA has approved no dose. In a 2023 test, 22 of 25 US gummies were more than 10% from their label.
Beetroot juice lowers resting blood pressure by about 3.5 mmHg, averaged over 43 comparisons from 19 controlled trials lasting 2 to 56 days. Juice with its nitrate removed did about 3 mmHg worse. Reviews that pooled 24-hour readings found no clear drop.
Meditation and yoga lower measured cortisol a little, on average, in pooled trials, most clearly in people under strain. Other stress markers moved too, mostly in different trials, and the few trials that tested whether cortisol is why yoga helps do not agree.