How much Coffee is TOO much Coffee?
If you’ve wondered how much coffee is too much, 
Save this blogg post for later 
If you know me you know I LOVE good Coffee #daily but I know my limits.. I am a 3 shot a day girl, occasionaly 1 more shot but anymore & I become a little too hypo + annoying & less productive. One man’s food is another man’s poison. And thanks to nutrigenetics, we now understand why.
For some people, certain foods can be beneficial, while for others, it can be detrimental. Coffee and milk are two perfect examples of this: For slow caffeine metabolisers, having more than 2 cups of coffee a day can dramatically increase their risk of having a heart attack. Whereas for fast caffeine metabolisers, 2-3 cups of coffee a day can actually reduce their risk of having a heart attack. 
For milk drinkers, if you’re lactose intolerant, having too much milk can make you feel bloated, gassy, nauseous, and give you stomach cramps, but for those who aren’t lactose intolerant, it provides them with a versatile and nutritious beverage. One size simply doesn’t fit all when it comes to nutrition!
If you’ve wondered how much coffee is too much, Save this blog for later because we’re here to tell you that it can depend on your genetics!
People often interchange the words coffee and caffeine as synonyms. But they are far from the same thing! Coffee is more than caffeine, and has 100’s of bioactive compounds that are good for you. The issue is caffeine, and in excess, it can be bad for you.
But, how much caffeine is OK? Or coffee for that matter? International recommendations say no more than 400mg of caffeine per day, or about 4 cups of coffee, and 8 cups of caffeinated tea (green/black tea). Research shows that this also depends on your genetics and whether you’re a slow or fast caffeine metaboliser. 1 in 2 people are ‘slow’ caffeine metabolisers, which means that caffeine stays in their system for longer. If you have a lot of caffeine, it has more opportunity to do ‘damage’. Research shows that slow caffeine metabolisers who consume over 200mg/day of caffeine (2 cups of coffee or 4 cups of tea) increase their risk of heart disease and prediabetes.
Current Research
Being Evidenced Based I like to geek out and look further into it afterall I think my brain and its functioning is important to me, especially as I moving into my 50’s. Out of ALL of the research into Coffee and its effect’s on the brain I found the research pertaining to Alzheimer’s the most fasinating.
A long-term Australian study has revealed that drinking higher amounts of coffee may reduce the risk of developing Alzheimer’s disease (AD) (1). AD is a neurodegenerative disease characterized by progressive impairment of learning, memory and other cognitive deficits, with extracellular deposition of Aβ-amyloid protein within the brain leading to neuroinflammation, synaptic loss and neuronal death (2).
Coffee is one of the most popular beverages consumed worldwide, due to its stimulating effects on the central nervous system as well as its taste and aroma. Epidemiological studies suggest coffee has beneficial effects on various conditions including stroke (3), dementia (3), heart failure (4), cancers (5), diabetes (6), and Parkinson’s disease (7).
Coffee consumption has previously been linked to decreased risk of mild cognitive impairment (MCI) and AD (8,9,10), however, this is the first study investigating the relationship of coffee intake to rates of decline in multiple cognitive domains. The study investigated the relationship between self-reported habitual coffee intake, and cognitive decline in 227 cognitively normal older adults (average age 69.7 years at baseline) over 126 months (10.5 years). Cognitive decline was assessed using a comprehensive neuropsychological battery. In a subset of individuals, the relationship between habitual coffee intake and cerebral Aβ-amyloid accumulation and brain volumes was also assessed. Results showed higher coffee consumption was associated with slower cognitive decline, specifically in the attention and executive function domains, which includes planning and self-control.
Higher coffee consumption was linked with a lower risk of transitioning from cognitively normal to MCI or AD status over 126 months. In the neuroimaging subset, higher coffee intake was associated with slower cerebral Aβ-amyloid accumulation, as well as lower risk of progressing to “moderate,” “high,” or “very high” Aβ-amyloid burden status over the same time period. Coffee consumption was not, however, associated with rates of grey matter, white matter or hippocampal volume atrophy.
The observed effect size estimates of the study suggest that increasing intake from one to two cups of homemade coffee (240g) per day could potentially provide up to 8% decrease in executive function decline over 18 months, and up to 5% decrease in cerebral Aβ-amyloid accumulation. Further longitudinal observational and intervention studies are required to substantiate this suggestion. A maximum number of cups per day that provided a beneficial effect was not able to be established from the current study. Coffee contains a range of bioactive compounds, including caffeine, chlorogenic acid, polyphenols and small amounts of vitamins and minerals (11).
While caffeine has been linked to the results in the current study, animal model studies of AD provide preliminary evidence to suggest the observed benefits are not due to caffeine alone. Crude caffeine, a by-product of the decaffeination process, is as effective as caffeine in partially preventing memory impairment in AD mice (12). Other coffee components such as cafestol, kahweol and eicosanoyl-5-hydroxytryptamide also affected cognitive impairment in animals in various studies (13,14,15). The blocking of adenosine receptors by caffeine, leading to a decrease in Aβ-amyloid in the brain, and subsequent reduction of tau hyperphosphorylation is a potential mechanism that warrants further investigation. This study adds to the growing evidence supporting the hypothesis that coffee intake may be a protective factor against AD.
A 2016 meta-analysis of nine prospective cohort studies found that drinking 1-2 cups of coffee per day was associated with a lower incidence of cognitive disorders (i.e., cognitive decline, cognitive impairment, AD, and all-cause dementia) compared with less than one cup. Studies ranged in follow-up from 1.3 to 28 years ([8)]. A recent cross-sectional analysis found self-reported lifetime intake of > 2 cups of coffee per day was associated with lower rates of “Aβ positivity” (presence of significant brain Aβ-amyloid), compared to < 2 cups per day (n=411 cognitively normal older adults). However, in this cohort, current coffee intake was not related to “Aβ positivity”, and neither current nor lifetime intake was related to brain volume or cerebral cortical thickness (16), consistent with findings from the current study (1). Limitations Known potential confounding factors were adjusted for in the study yet there is a possibility of residual confounding factors that were not measured. Due to the nature of the study, there is the possibility of measurement error or recall bias concerning dietary data.
Coffee intake, however, is less prone to misreporting due to its long-term habitual nature. No data on mid-life coffee consumption was obtained, therefore potential deleterious or beneficial effects of coffee intake at midlife were not assessed. Lastly, the study was unable to differentiate between caffeinated and decaffeinated coffee, nor the benefits or consequences of preparation methods (brewing method, added milk and/or sugar etc.).
Conclusion
Increased coffee consumption potentially reduces cognitive decline by slowing cerebral Aβ-amyloid accumulation, attenuating the associated neurotoxicity from Aβ-amyloid-mediated oxidative stress and inflammatory processes. It is yet to be determined precisely which constituents of coffee are behind its positive effects on brain health and further research is required evaluating whether coffee intake could one day be recommended as a lifestyle factor aimed at delaying the onset of AD.
References:
1: Gardener SL, Rainey-Smith SR, Villemagne VL, Fripp J, Doré V, Bourgeat P, et al. Higher Coffee Consumption Is Associated With Slower Cognitive Decline and Less Cerebral Aβ-Amyloid Accumulation Over 126 Months: Data From the Australian Imaging, Biomarkers, and Lifestyle Study. Frontiers in Aging Neuroscience. 2021;13:681.
2: Villemagne VL, Burnham S, Bourgeat P, Brown B, Ellis KA, Salvado O, et al. Amyloid β deposition, neurodegeneration, and cognitive decline in sporadic Alzheimer’s disease: a prospective cohort study. Lancet Neurol. 2013 Apr;12(4):357–67.
3: Zhang Y, Yang H, Li S, Li W, Wang Y. Consumption of coffee and tea and risk of developing stroke, dementia, and poststroke dementia: A cohort study in the UK Biobank. PLoS Med. 2021 Nov 16;18(11):e1003830.
4: Mostofsky E, Rice MS, Levitan EB, Mittleman MA. Habitual Coffee Consumption and Risk of Heart Failure: A Dose–Response Meta-Analysis. Circ Heart Fail. 2012 Jul 1;5(4):401–5.
5: Wang A, Wang S, Zhu C, Huang H, Wu L, Wan X, et al. Coffee and cancer risk: A meta-analysis of prospective observational studies. Sci Rep. 2016 Sep 26;6:33711.
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7: Ross GW, Abbott RD, Petrovitch H, Morens DM, Grandinetti A, Tung KH, et al. Association of coffee and caffeine intake with the risk of Parkinson disease. JAMA. 2000 May 24;283(20):2674–9.
8: Liu Q-P, Wu Y-F, Cheng H-Y, Xia T, Ding H, Wang H, et al. Habitual coffee consumption and risk of cognitive decline/dementia: A systematic review and meta-analysis of prospective cohort studies. Nutrition. 2016 Jun;32(6):628–36.
9: Wu L, Sun D, He Y. Coffee intake and the incident risk of cognitive disorders: A dose-response meta-analysis of nine prospective cohort studies. Clin Nutr. 2017 Jun;36(3):730–6.
10: Wierzejska R. Can coffee consumption lower the risk of Alzheimer’s disease and Parkinson’s disease? A literature review. Arch Med Sci. 2017 Apr 1;13(3):507–14.
11: Spiller MA. The Chemical Components of Coffee. In: Caffeine. 1st ed. Florida: CRC Press; 1998.
12: Chu Y-F, Chang W-H, Black RM, Liu J-R, Sompol P, Chen Y, et al. Crude caffeine reduces memory impairment and amyloid β(1-42) levels in an Alzheimer’s mouse model. Food Chem. 2012 Dec 1;135(3):2095–102.
13: Higgins LG, Cavin C, Itoh K, Yamamoto M, Hayes JD. Induction of cancer chemopreventive enzymes by coffee is mediated by transcription factor Nrf2. Evidence that the coffee-specific diterpenes cafestol and kahweol confer protection against acrolein. Toxicol Appl Pharmacol. 2008 Feb 1;226(3):328–37.
14: Basurto-Islas G, Blanchard J, Tung YC, Fernandez JR, Voronkov M, Stock M, et al. Therapeutic benefits of a component of coffee in a rat model of Alzheimer disease. Neurobiol Aging. 2014 Dec;35(12):2701–12.
15: Asam K, Staniszewski A, Zhang H, Melideo SL, Mazzeo A, Voronkov M, et al. Eicosanoyl-5-hydroxytryptamide (EHT) prevents Alzheimer’s disease-related cognitive and electrophysiological impairments in mice exposed to elevated concentrations of oligomeric beta-amyloid. PLoS One. 2017;12(12):e0189413.
16: Kim JW, Byun MS, Yi D, Lee JH, Jeon SY, Jung G, et al. Coffee intake and decreased amyloid pathology in human brain. Transl Psychiatry. 2019 Oct 22;9(1):270.