That was a high-falutin intro for such duh-treatment: eat more veg, less animal, exercise, moderate stress.
The supplements are more or less placebo though B12 good idea for everyone.
Nutritionfacts.org summarizes this approach nicely
Generally agreed now that saturated fat and it's affect on brain blood flow is the main culprit. Weight loss drops blood cholesterol so even illness that cause weight loss can have positive impact on AD