The UK's Food Standards Agency says taking more than 200 milligrams a day of vitamin B6 can lead to a loss of feeling in the arms and legs, but these symptoms are reversible once someone stops taking the supplements.

BBC: Vitamin B 'puts off Alzheimer's'

But this change appears to be reversible, and not to lead to permanent brain damage.

BBC: NEWS | Health | Smoking diseases alter the brain

But such early gains are still reversible.

ECONOMIST: Tunisia and the Arab world

But as Mr Celik outlines the possible applications for reversible data-hiding, it becomes obvious why preserving image integrity is so critical.

ECONOMIST: MONITOR

But the gains achieved so far are tenuous and reversible.

WSJ: Max Boot: Bin Laden's Death Changes Little

Elevations of liver enzymes, a possible warning sign, have been noted in some patients, but Lehman analysts quote Schering's management as insisting that these were reversible and didn't cause any symptoms.

FORBES: Schering Gets Plowed

But longer exposure to the gene protein might lead to other cancer-causing abnormalities, which would not be reversible.

BBC: Leukaemia 'on-off switch' discovered