Daily caffeine intake in children, adolescents, and adults is below recommended levels, with coffee, tea, and soft drinks being the main sources, and energy drinks contributing little.

Caffeine intake and its sources: A review of national representative studies

Moderate daily caffeine intake up to 400 mg for healthy adults is not associated with adverse effects, while reproductive-aged women and children require specific advice on limiting intake.

Effects of caffeine on human health

Daily coffee and caffeine intake is not harmful and can improve brain health, alertness, concentration, and mood, with potential benefits for preventing cognitive decline and reducing the risk of stroke, Parkinson's, and Alzheimer's diseases.

Effects of coffee/caffeine on brain health and disease: What should I tell my patients?

Mean caffeine intakes in US consumers are within safe levels, but heavy consumers of caffeine, particularly in young children and women contemplating pregnancy, may benefit from dietary advice.

Beverage caffeine intake in US consumers and subpopulations of interest: estimates from the Share of Intake Panel survey.

Swiss adults consume an average of 191 mg/day of caffeine, with coffee (83%), tea (9%), and soft drinks (4%), with caffeine consumption peaking between 06:00 and 09:00 (29%) and varying across age groups and linguistic regions.

Caffeine Consumption in Switzerland: Results from the First National Nutrition Survey MenuCH

Single doses up to 200 mg and habitual consumption up to 400 mg per day do not pose safety concerns for healthy adults, while pregnant women and lactating women do not face concerns for breastfed infants.

Scientific Opinion on the safety of caffeine

Moderate caffeine intake may decrease anxiety in postmenopausal females with overactive bladder symptoms, but does not affect depression, insomnia, or perceived stress.

The Impact of Caffeine Intake on Mental Health Symptoms in Postmenopausal Females with Overactive Bladder Symptoms: A Randomized, Double-Blind, Placebo-Controlled Trial.

Caffeine intake levels previously determined not to cause adverse health effects by Health Canada remain appropriate for healthy adults, pregnant women, adolescents, and children, supporting a shift in research focus from healthy to sensitive populations.

Key Findings and Implications of a Recent Systematic Review of the Potential Adverse Effects of Caffeine Consumption in Healthy Adults, Pregnant Women, Adolescents, and Children

Reducing coffee consumption is the most effective way to reduce caffeine intake in adolescents and young adults aged 14-39 years in Austria.

Caffeine intake from all sources in adolescents and young adults in Austria

Caffeine consumption up to 400 mg daily for healthy adults and 200 mg for pregnant and breastfeeding women is considered safe, with 95% of those questioned within the safe range.

Caffeine – stimulating and aromatic: but safe!

Caffeine acts as an antimicrobial agent, reducing Escherichia coli growth rates more in nutrient-poor conditions, but not in anoxic conditions.

Nutrients mediate caffeine inhibition of Escherichia coli

Higher caffeine intake in high school students is associated with lower nutritional knowledge and poorer sleep health compared to low caffeine intake groups.

How Much Caffeine is Too Much for Young Adolescents?

High doses of caffeine (400 mg) can enhance vigilance and executive control of visual attention in habitual consumers, but only at the highest administered dose.

Acute caffeine consumption enhances the executive control of visual attention in habitual consumers

Excess caffeine consumption can enhance response speed in complex managerial decisions, but may decrease opportunity utilization.

Excess coffee consumption in simulated complex work settings: detriment or facilitation of performance?

Caffeine consumption may negatively impact fertilization rates in both men and women, but its effect on one-carbon metabolism remains unclear.

The Effect of Caffeine Consumption on Fertilization and IVF Outcomes: A Review and Presentation of Original Data

Caffeine consumption at levels of 200 mg or 400 mg daily (around 5 cups) is not risky and can enhance productivity, focus, and reduce distress, with potential benefits for mental health and reduced risk of stroke, Parkinson's, and Alzheimer's diseases.

Effects of Caffeine on Human Body

Caffeine intake of 400 mg per day in healthy adults does not cause significant cardiovascular side effects, reproductive changes, or acute consequences, and does not affect calcium exchange in bone tissue.

[Potential side effects of caffeine consumption in healthy adults, pregnant women, adolescents and children (review of foreign literature)].

The U.S. population consumes at least one caffeinated beverage per day, with coffee being the primary contributor to caffeine intake, and carbonated soft drinks and tea being more prevalent in younger age groups.

Beverage caffeine intakes in the U.S.

Moderate caffeine consumption (300 mg per day) is safe and can improve mental and physical performance, but children should not consume more than 45 mg per day.

The effects of caffeine.

Chronic caffeine intake can lead to upregulation of platelet adenosine A(2A) receptors, resulting in increased sensitization to the actions of the agonist HE-NECA.

Dose and time effects of caffeine intake on human platelet adenosine A(2A) receptors : functional and biochemical aspects.

These studies suggest that a daily caffeine intake of up to 400 mg is safe for healthy adults.