Evidence is consistent, with known limits.
Around 117,000 Japanese adults were followed for years, and people who said their life felt worth living died less. None of those studies used the four-circle diagram — which began life in 2012 with a different word in the middle: purpose.
A 2025 meta-analysis of 24 cohorts found 7,000 steps a day linked to 47% lower mortality, 38% less dementia and 22% fewer depressive symptoms — with the curve bending around 5,000 to 7,000. Cancer risk did not move. And your age changes where the number sits.
Across 34 double-blind trials, magnesium lowered blood pressure about 2 points — small, real, and the authors called it causal. Cochrane found nothing at all for leg cramps, at high certainty. And the entire sleep evidence base is three trials in 151 people.
A 790-man NIH trial and an individual-participant meta-analysis of 35 trials both find real improvement in sexual function and quality of life. The trial designed to test energy found nothing. And the only trial big enough to count fractures found 43% more of them.
Of 3,334 men, 277 had a normal total testosterone and a low free testosterone — and they had the symptoms. Ninety-six had the reverse, and did not. Plus why the free number on your report was probably calculated with an equation its own field calls faulty.
Processed meat carries an 18% higher colorectal cancer risk per 50 g a day — and two reviews covering four and six million people concluded the absolute effects are 'very small' with low-certainty evidence. Both are true. Here is why, what IARC's Group 1 actually means, and why steak is a different question.
Pooled across 72 measurements, instant oatmeal scored 75 on the glycaemic index and granola scored 56 — the breakfast with the health halo performs worse than the one people feel guilty about. The real, regulator-approved oat claim is about cholesterol, at 3 g of beta-glucan a day, and it saturates there.
The famous PREDIMED trial was retracted from the New England Journal of Medicine and republished — and the nuts arm did just as well as the olive oil arm. Across 92,000 people over 28 years, olive oil beat butter and margarine handily. Against other vegetable oils, no significant difference at all.
Same trial, same 59 people, same 40-gram dose: lactitol caused severe symptoms across the board and maltitol caused no laxative effect at all. Both are labelled sugar alcohols. Europe's regulator set a limit on erythritol for diarrhoea — not clots — and refused to drop the warning label. And the erythritol and xylitol heart scares came from one dataset.
Nineteen people ate 441 calories a day less without being told to, purely from moving protein from 15% to 30% of their meals — with the appetite hormones pushing the other way. But when 38 foods were ranked head to head, the most filling was a boiled potato, and water content predicted fullness better than protein did.