Scientists targeted a process that allows harmful clumps of protein in the brain to kill off neurons.
Using purified extracts of the chemicals EGCG in green tea and resveratrol in red wine, they were able to stop nerve cells from being harmed.
The findings, published in the Journal of Biological Chemistry, could pave the way for new drugs to treat Alzheimer's, say the researchers.
Lead scientist Professor Nigel Hooper, from the Leeds University, said: "This is an important step in increasing our understanding of the cause and progression of Alzheimer's disease. It's a misconception Alzheimer's is a natural part of ageing; it's a disease we believe can ultimately be cured through finding new opportunities for drug targets like this."
Dr Simon Ridley, from the charity Alzheimer's Research UK which part-funded the study, said: "Understanding the causes of Alzheimer's is vital if we are to find a way of stopping the disease in its tracks."