What are the safe levels of caffeine intake?

From the Guidelines

For most healthy adults, consuming up to 400 mg of caffeine per day is considered safe, as supported by the most recent and highest quality study 1. This is roughly equivalent to 4 cups of brewed coffee, 10 cans of cola, or 2 energy shot drinks. Pregnant women should limit intake to 200 mg daily, as recommended by the European Food Safety Authority 1, while adolescents should consume no more than 100 mg per day. Children under 12 should generally avoid caffeine. Individual sensitivity varies, so some people may need to consume less. Caffeine works by blocking adenosine receptors in the brain, which helps prevent drowsiness and temporarily increases alertness. It typically takes 4-6 hours for half of the caffeine to be metabolized in your body. Consuming caffeine late in the day can interfere with sleep quality, so it's best to avoid it within 6 hours of bedtime. Signs of excessive caffeine consumption include jitteriness, anxiety, rapid heartbeat, insomnia, and digestive issues. Some key points to consider when evaluating safe levels of caffeine intake include:

• The amount of caffeine in a serving of coffee can vary greatly, depending on factors such as the type of coffee bean, roasting method, and brewing technique 1.
• The mean caffeine intake in the United States is approximately 165 mg per day, with coffee being the primary source of caffeine 1.
• High caffeine intakes, such as those above 5 mg/kg body weight per day, have been associated with an increased risk of anxiety and withdrawal symptoms in children 1.
• The American College of Cardiology and American Heart Association recommend limiting caffeine intake to less than 300 mg per day, especially for patients with uncontrolled hypertension 1. People with certain health conditions like heart problems, high blood pressure, or anxiety disorders should consult healthcare providers about appropriate caffeine limits. Overall, moderate caffeine consumption, defined as up to 400 mg per day, can be a part of a healthy diet for most adults, but individual factors and sensitivity should be taken into account.

From the FDA Drug Label

Serious toxicity has been reported in the literature when serum caffeine levels exceed 50 mg/L The FDA drug label does not answer the question of safe levels of caffeine intake in the general population, but it does mention that serious toxicity has been associated with serum levels greater than 50 mg/L in infants.

• The information provided is specific to infants and caffeine citrate administration.
• Safe levels of caffeine intake are not explicitly stated for the general population.
• The label does mention that caffeine levels ranged from 8 to 40 mg/L in a placebo-controlled clinical trial, but this is not a direct answer to the question of safe levels of caffeine intake. 2, 2, 2

From the Research

Safe Levels of Caffeine Intake

• The safe level of caffeine intake varies among different populations, including healthy adults, pregnant women, adolescents, and children.
• According to a systematic review published in 2017 3, consumption of up to 400 mg caffeine/day in healthy adults is not associated with overt, adverse cardiovascular effects, behavioral effects, reproductive and developmental effects, acute effects, or bone status.
• For healthy pregnant women, the same review suggests that consumption of up to 300 mg caffeine/day is generally not associated with adverse reproductive and developmental effects.
• The available evidence for child and adolescent populations is limited, but it suggests that 2.5 mg caffeine/kg body weight/day remains an appropriate recommendation 3.
• Another study published in 2017 4 found that cardiovascular effects experienced by caffeine consumers at levels up to 600 mg/day are in most cases mild, transient, and reversible, with no lasting adverse effect.
• A review of current research on caffeine and cardiovascular diseases published in 2016 5 highlights the need for further study to determine the safe dose of caffeine, as the population does not appear to adhere to the strict guidelines listed on caffeine consumption.

Population-Specific Guidelines

• Healthy adults: up to 400 mg caffeine/day 3
• Healthy pregnant women: up to 300 mg caffeine/day 3
• Children and adolescents: 2.5 mg caffeine/kg body weight/day 3
• Note: These guidelines are based on the available evidence and may need to be revised as new research emerges.

Cardiovascular Effects

• Moderate caffeine intake is not associated with increased risks of total cardiovascular disease, arrhythmia, heart failure, blood pressure changes, or hypertension in baseline populations 4.
• Habitual consumption of moderate amounts of coffee seems to lead to less arrhythmias, according to a review of clinical trials and meta-analyses published in 2023 6.
• A condensed review of epidemiological evidence and mechanisms published in 2018 7 found that habitual consumption of 3-5 cups of coffee per day is associated with a 15% reduction in the risk of cardiovascular disease in healthy people.