Topic
Caffeine & Health
Plain-English summaries of caffeine and coffee health research: how much caffeine is in coffee, safe daily amounts, sleep, blood pressure, digestion, and more — with citations to primary sources.
Articles
48 published
Articles in Caffeine & Health
- 01
Coffee vs Red Bull: The Caffeine Comparison Goes the Other Way
Red Bull is a weaker caffeine solution than brewed coffee, ounce for ounce. The difference between the two drinks is sugar, not stimulant.
- 02
Coffee vs Energy Drinks: What the Research Actually Compares
A Red Bull has less caffeine than a cup of coffee, yet only one of them is legally capped and carries a warning label. The difference is not the caffeine.
- 03
What 8,687 Coffee Studies Have Actually Tested in People
We indexed the coffee and caffeine literature and sorted it by study design. Some claims rest on hundreds of human trials. Others rest almost entirely on rodents.
- 04
The Coffee Nap: What the Sleep Research Actually Shows
Drink a coffee, sleep twenty minutes, wake as it takes effect. The mechanism is sound and the direct evidence is thinner than the internet suggests.
- 05
Coffee and the Prostate: Two Questions With Opposite Answers
Coffee and prostate cancer risk, and coffee and urinary symptoms, are different questions. The research answers them in different directions.
- 06
Does Caffeine Raise Your Heart Rate? What Trials Measured
Controlled trials disagree about the direction, and the size of the change is a few beats per minute. Blood pressure is the more consistent finding.
- 07
Why Do Plants Make Caffeine? The Evolutionary Biology
The evolutionary reasons plants produce caffeine — insect defense, allelopathy, and pollinator manipulation — and why caffeine evolved independently four times.
- 08
Coffee and Parkinson's Disease: What the Research Shows
The evidence linking coffee and caffeine to reduced Parkinson's disease risk — the JAMA 2000 study, A2A receptor mechanism, and why decaf shows no effect.
- 09
Does Coffee Raise Blood Sugar?
Whether coffee raises blood sugar: caffeine's acute effect on insulin sensitivity and glucose, what the research shows for healthy adults and people with
- 10
Coffee and Weight Loss: What the Research Actually Shows
The evidence behind coffee and weight loss — thermogenic effect, fat oxidation, chlorogenic acid research, what the randomised trials show
- 11
Caffeine and Dopamine: Why Coffee Feels Rewarding
How caffeine indirectly boosts dopamine through adenosine receptor interactions, why this makes coffee feel rewarding
- 12
Best Time to Drink Coffee: What the Science Actually Says
When to drink coffee based on caffeine half-life, sleep timing research, adenosine rebound, and pre-workout evidence
- 13
Does Coffee Cause Constipation?
Coffee's paradoxical constipation effect: why the same drink that stimulates bowel movement in most people can cause constipation in others.
- 14
Does Coffee Cause Bloating? Gut Effects Explained
Why coffee can cause bloating: gas from colon stimulation, lactose in milk drinks, sugar alcohols in sweeteners, and gut motility effects
- 15
Coffee and Vyvanse (and Other ADHD Medications)
How coffee interacts with Vyvanse, Adderall, and other ADHD stimulants: overlapping mechanisms, cardiovascular considerations, timing
- 16
Coffee and Iron Absorption: How Much Does It Block?
How coffee blocks iron absorption: the polyphenols responsible, how much iron absorption drops, when it matters
- 17
Coffee Addiction: Are You Actually Addicted?
What coffee 'addiction' really means: physical dependence vs behavioural addiction, how caffeine differs from addictive drugs
- 18
Is Coffee Healthy? What Large Studies Actually Show
Is coffee healthy? What decades of large cohort studies and systematic reviews actually show — the benefits, the risks, and what the evidence supports.
- 19
How Much Caffeine Is Too Much?
Safe daily and single-dose caffeine limits, when caffeine becomes dangerous, how tolerance shifts the threshold, and what the FDA and Health Canada recommend.
- 20
How Caffeine Works: The Adenosine Mechanism
How caffeine actually wakes you up: the adenosine receptor mechanism explained, why tolerance develops, how genetics change your response
- 21
Does Coffee Make You Poop? The Science Behind It
Coffee and the gastrocolic reflex: what controlled studies actually show about coffee's laxative effect, why decaf works too, and who's most sensitive.
- 22
Does Coffee Dehydrate You? What Studies Show
Does coffee dehydrate you? What controlled studies actually show — the myth vs the real, small diuretic effect, and what a typical intake means in practice.
- 23
Does Coffee Break a Fast? Black Coffee and Fasting Rules
Does coffee break a fast? Black coffee vs coffee with milk or sugar, what research shows about caffeine's effect on insulin and autophagy
- 24
Coffee Withdrawal Symptoms: Headaches, Timeline, Relief
What caffeine withdrawal actually feels like, how long it lasts, why headache is the most common symptom, and how to quit or cut back without the crash.
- 25
Coffee on an Empty Stomach: Is It Bad for You?
Coffee on an empty stomach — what actually happens physiologically, why some people feel nauseous and others fine, and what the research shows about cortisol.
- 26
Coffee Before a Workout: Timing, Dose, and Performance
Caffeine as a pre-workout: what the ISSN position stand says about dose, timing, and effect size across endurance, strength, and high-intensity exercise.
- 27
Coffee Antioxidants: What the Research Shows
The antioxidant compounds in coffee — chlorogenic acids, melanoidins, and caffeic acid — what they are, what research shows about their effects.
- 28
Coffee and Pregnancy: Safe Limits and What Research Shows
Coffee during pregnancy: Health Canada's 200 mg daily limit, what studies show about fetal growth, and the evidence behind pregnancy caffeine guidelines.
- 29
Coffee and Liver Health: What Cohort Studies Show
Coffee and liver health: what large cohort studies show about fibrosis, cirrhosis, and hepatocellular carcinoma risk — and whether decaf shows the same effects.
- 30
Is Coffee Bad for Your Kidneys?
Is coffee bad for your kidneys? What large cohort studies actually show about coffee and chronic kidney disease, kidney stones, and hydration.
- 31
Does Coffee Cause Inflammation?
Coffee and inflammation: what large C-reactive protein studies show, why coffee's polyphenols matter, and where the 'inflammatory coffee' myth comes from.
- 32
Coffee and the Gut Microbiome: What Research Shows
What research shows about coffee's effect on gut bacteria — including the discovery of a coffee-linked bacterial species and what habitual drinking does
- 33
Coffee and Gout: Does Caffeine Affect Uric Acid?
Coffee, uric acid, and gout: what the Health Professionals Follow-Up Study and Nurses' Health Study show, why decaf works too, and the acute-flare caveat.
- 34
Coffee and Diabetes: What Studies Show About Risk
Coffee and type 2 diabetes: what large cohort studies show, why decaf shares much of the benefit, and how add-ins can reverse the effect entirely.
- 35
Coffee and Cortisol: When to Drink for Your Hormones
Coffee and cortisol: what controlled research shows about the stress hormone response to caffeine, why tolerance matters, and the best time to drink.
- 36
Coffee and Cholesterol: Cafestol, Diterpenes, and Risk
Coffee and LDL cholesterol: why cafestol and kahweol in unfiltered coffee raise blood lipids, what filter methods remove, and what the meta-analyses show.
- 37
Coffee and ADHD: What the Research Actually Shows
Caffeine, coffee, and ADHD: why the 'paradoxical calming' has a real mechanism, what systematic reviews of caffeine in ADHD show
- 38
Coffee and Acid Reflux: What Actually Causes It
Coffee and acid reflux: what the research shows, why some drinkers react more than others, and what actually reduces symptoms — roast, timing, and acids.
- 39
Caffeine Tolerance: How It Builds and How to Reset It
Why the same coffee stops feeling like it works: adenosine receptor upregulation, which caffeine effects tolerate faster, and how to reset tolerance.
- 40
Caffeine Headache: Why Coffee Both Causes and Cures Them
The two-way relationship between caffeine and headaches: why acute caffeine can relieve headaches, why withdrawal causes them
- 41
Caffeine Half-Life: How Long Caffeine Stays in Your Body
Caffeine half-life, plainly: what it is, why individual metabolism varies so much, how to estimate how much caffeine is still in your system
- 42
The Caffeine Crash: What It Is and Why It Happens
Why energy dips after caffeine wears off: the adenosine rebound mechanism, the blood sugar contribution, and what may help reduce the crash.
- 43
The Caffeine Chemical Structure
What caffeine actually is at the molecular level: a purine alkaloid in the methylxanthine class, its structure, plant biosynthesis
- 44
Black Coffee Benefits: What Large Studies Actually Show
Evidence-based benefits of drinking black coffee: what large cohort studies show about metabolic, cognitive, and cardiovascular effects
- 45
How Much Caffeine Is in Coffee?
How much caffeine is in a cup of coffee? Typical amounts for brewed, espresso, instant, decaf, and cold brew — and what actually changes the number.
- 46
Coffee and Sleep: What Research Shows
How caffeine affects sleep — dose, timing, the six-hour rule, tolerance, and why the same afternoon coffee can leave one person wired and another asleep.
- 47
Coffee and Blood Pressure: What the Research Shows
Does coffee raise blood pressure long term? What the research shows about acute vs sustained effects, individual sensitivity, and who should be cautious.
- 48
Coffee and Anxiety: What the Research Shows
How caffeine affects anxiety — dose thresholds, genetic sensitivity, when a cup crosses the line from stimulating to unsettling, and who is most at risk.