When researchers ran DNA testing on 13 herbal products, only 2 contained the plant on the label. Three had none of it at all, and several were padded out with rice, soy or wheat that nobody had declared.

Working out what you have comes before choosing what to take. The right remedy for the wrong condition is still the wrong remedy, however good the remedy happens to be.

Irritable bowel symptoms turn up more often in people with ADHD, and they tend to track stress. If your stomach is at its worst in the weeks when everything else is at its worst, that is information rather than coincidence.

If you are testing whether a food affects you or your child, the test has to be complete. Among children with suspected sensitivity to artificial colouring, most reacted to as little as 100 mg, so a bit left in is enough to blur the answer.