Scientists have discovered a method of genetically-modifying the fruit so that when eaten it will boost the immune system to tackle the brain-wasting condition which affects memory, mood and behaviour.

The technique involves combining genes from a protein that causes the disease with the tomato genome.

Once eaten, the body’s defence mechanism recognises the protein and launches an attack to destroy it, say scientists at the Korea Research Institute of Bioscience and Biotechnology in Seoul.

Alzheimer’s, which has no cure, affects an estimated 750,000 people in Britain. That number is expected to more than double in the next 40 years as the population ages.

Researchers chose tomatoes as ideal for an edible vaccine because they can be eaten without heat treatment, which could destroy their effectiveness.

In experiments on mice, blood samples showed the tomatoes triggered the release of disease-fighting antibodies.

The team is now investigating how to increase the potency of the vaccine in order to “supercharge” the body’s immune response.

The researchers said: “This study represents a unique approach in which transgenic plants expressing the protein are used to produce a vaccine.”