Coffee (Quercetin) ('07, '11, '16, '18-'19) & Alzheimer's
Coffee (1-3 cups per day, recommended dosages can vary depending in certain body types). Quercetin, not caffeine, is the major neuroprotective element in coffee, consumption of which reduces the risk of Alzheimer's. Although study results are not consistent, 3 out of 5 reviewed supported coffee's favorable effects against cognitive decline, dementia, or AD.
Lee M, McGeer MG, McGeer PL. (2016). Quercetin, not caffeine, is a major neuroprotective component in coffee. Neurobiol Aging. Oct;46:113-23.
A 2007 review of observational studies suggested that coffee consumption was associated with a reduced risk of AD by approximately by 30% as compared to non-coffee consumer.
Barranco Quintana J.L. et al. (2007) Alzheimer's disease and coffee: a quantitative review.Neurol Res, 29:91-5.
Coffee combined with melatonin has been shown to have a range of benefits including antioxidative, antiapoptotic and neuroprotective effects.
Coffee and its consumption: benefits and risks. Butt MS, Sultan MT Crit Rev Food Sci Nutr. 2011 Apr; 51(4):363-73
A meta-analysis (a study of studies) found, however, that there's no direct correlation between coffee consumption and relative risk of developing Alzheimer's disease, but called for further research.
Larsson SC, Orsini N. (2018). Coffee Consumption and Risk of Dementia and Alzheimer's Disease: A Dose-Responsive Meta-Analysis of Prospective Studies. Nutrients. Oct 14;10(10):1501.
However, quercetin, an amino acid contained in coffee, does have notable beneficial effects including being neuroprotective, reducing lipid oxidation, inhibiting amyloid beta fibril formation, reducing inflammation, etc. It therefore may be considered as part of AD therapy.
Khan H, Ullah H, Aschner M, Cheang WS, Akkol EK. (2019). Neuroprotective Effects of Quercetin in Alzheimer's Disease. Biomolecules. Dec 30;10(1):59.