Evidence Files

What Your Genes Really Decide, and What They Don't

Same genes, different lives: Pima Indians in Arizona have type 2 diabetes at a rate of 38%, while their genetic relatives in the mountains of Mexico have it at 6.9%. Height in men is 87–93% heritable, yet South Korean women grew 20 centimetres taller in a single century. This explainer is about where genes really decide, where they only shift the odds, and why “it runs in the family” almost never means “nothing can be done”.

Proven for Rare Epilepsy, at 700 Times the Dose EU Regulators Call Safe in Food

In the trials that made CBD a licensed medicine, patients with severe childhood-onset epilepsy took **20 mg per kilogram of body weight** every day. In February 2026, the EU's food safety authority set a provisional safe intake for CBD food supplements of **0.0275 mg per kilogram**, about 2 mg a day for an adult. The oils and gummies sold for calm, sleep and pain are backed by neither: their evidence is far thinner than the epilepsy data they borrow their reputation from.

What the Evidence Actually Shows — and What Doubt Costs

Over fifty years, vaccination has prevented 154 million deaths — most of them babies. The supposed link between the measles vaccine and autism has been tested in more than a million children and not found. And in 2025–2026, the United States recorded more than 3,500 measles cases, enough to put its elimination status, held since 2000, under formal review. This explainer covers what is known for certain, which vaccine risks are real, and why doubt here costs more than it seems.

Two Giant Trials, No Protection for Your Heart — and One Surprise About Memory

Two randomised trials followed **more than 36,000 people** taking a daily multivitamin or a placebo, one of them for over a decade. Heart attacks, strokes, deaths: no difference. A study of **390,124 adults** followed for up to 27 years found no survival benefit either. And yet the most interesting result in the field is a positive one — just not where the label points.

The Benefit Vanishes When Someone Else Pays for the Trial

A 2025 meta-analysis of **23 randomised trials** found that collagen supplements improve skin hydration, elasticity and wrinkles. Then the authors split the trials by who paid for them. In the ones without pharmaceutical funding, **the effect disappeared** — and it disappeared again in the high-quality trials.

The Effect Shrinks Every Time the Study Gets Better

In the largest independent trial ever run on these supplements, **60.1% of the people taking a sugar pill** reported that their knee pain had improved by a fifth. Glucosamine beat that by 3.9 percentage points, which did not reach significance (P = 0.30). That single number explains most of what follows.

What It Actually Changes — and What It Never Does

A pill with no active ingredient releases dopamine in the brains of Parkinson's patients and dulls pain through the same receptors as morphine. Yet in the most elegant experiment on the subject, it made asthma patients feel just as improved as a real inhaler — while doing nothing whatsoever to their lungs. The gap between “I feel better” and “I am better” is where the entire economy of unproven medicine lives.

Why Most Lozenges on the Shelf Are the Wrong Dose

In 2024, Cochrane pooled 34 trials and 8,526 participants and delivered a shrug: zinc doesn't prevent colds, and its effect on duration is real but modest. What that headline number hides is a decade-old finding that most zinc products on pharmacy shelves were never dosed to work in the first place — and a live methodological fight over whether Cochrane's own math undersold the drug that does.