Just as an apple a day is said to keep the doctor away, Korean researchers hope that a tomato a week might keep Alzheimer's disease away.

Scientists are looking into whether the tomato might be a suitable carrier for an oral vaccine against the devastating neurodegenerative disease.

In a paper published online Tuesday in Biotechnology Letters, scientists from the Korea Research Institute of Bioscience and Biotechnology said they've made a promising first step toward finding an edible vaccine.

Alzheimer's is the most common form of dementia, affecting one in 20 Canadians over 65 — about 290,000.

Doctors believe it is caused by the buildup of a toxic protein in the brain called beta-amyloid, which kills brain cells.

Reducing the accumulation of beta-amyloid may put the brakes on brain cell death and therefore prevent or delay the onset of Alzheimer's disease.

One way to do that is to stimulate the immune system, through vaccination, to reduce the accumulation of beta-amyloid.

Attractive candidate

The Korean scientists' aim was to develop a plant-derived vaccine since beta-amyloid is toxic to animal cells.

Tomatoes are an attractive candidate as a vaccine carrier because they can be eaten without heat treatment. Heat increases the risk of destroying the vaccine's immune stimulation potential.

The researchers inserted the beta-amyloid gene into the tomato genome and measured the immune responses in a group of 15-month-old mice.

They fed the mice the transgenic tomatoes once a week for three weeks and also gave them a booster seven weeks after the first tomato vaccination.

Blood analyses showed a strong immune response after the booster, with the production of antibodies.

"Although we did not reveal a reduction of existing plaques in the brain of mice challenged with tomato-derived beta-amyloid … this study represents a unique approach in which transgenic plants expressing beta-amyloid protein are used to produce a vaccine," the authors write.

The team is now looking into how they might increase the potency of the tomato-based vaccine.