What’s the maximum safe dose of caffeine per day?

maximum dose of caffeine

The maximum safe dose of caffeine is 400 mg for healthy adults. Pregnant women could consume up to 200 mg of caffeine a day, while the upper safe dose for children older than 12 years and teenagers is only 100 mg.

Does caffeine have any health benefits?

Caffeine is the most popular natural stimulant of the central nervous system.

People consume caffeine to fight fatigue or drowsiness. But, caffeine has more health benefits than just increasing energy levels.

Actually, caffeine may help treat migraine headaches, depression, and neurocognitive declines, which are common adverse effects of Alzheimer and Parkinson disease![1]

Moreover, caffeine may improve digestion, due to increased gastric acid secretion and gastrointestinal motility. Also, it may improve breathing.

Furthermore, caffeine may enhance athletic performance. Especially, in endurance sports.

Most noteworthy, caffeine may help relax vascular muscle, as it stimulates endothelial cells to release nitric oxide.

Additionally, caffeine is a key compound in certain supplements which are supposed to be beneficial for weight loss, postprandial hypotension, low blood pressure, asthma, and pain relief. Caffeine may be an appetite suppressant and may increase metabolism.[2]

In fact, moderate amounts of caffeine seem to decrease all-cause mortality!

What’s the maximum safe dose of caffeine a day?

There hasn’t been established a maximum safe dose of caffeine. But, as a rule of thumb, a daily dose up to 400 mg is considered pretty safe for healthy adults.

A daily caffeine intake of 100 mg generally increase caffeine blood levels by 5 to 6 mg/L. Toxicity and adverse effects, such as vomiting, hypotension, tachycardia, or arrhythmia may occur at blood levels of 80-280 mg/L.

Most people should consume dosages greater than 150-200 mg per kg (2.2 lbs) in order to experience severe side effects.

But, people may experience side effects by consuming much lower caffeine doses of 1,200 mg. Therefore, adults better consume no more than 400 mg of caffeine a day.

Certainly, the maximum safe doses for kids, teenagers, pregnant, and lactating women is even lower.

In fact, the American College of Obstetricians and Gynecologists highly recommends that the upper safe dose of caffeine for pregnant women should be only 200 mg. According to some studies, the consumption of doses greater than 400 mg a day may lead to increased risk of miscarriage and lower birth weight.[3]

Lactating women should be careful about their daily caffeine intake as well. High amounts of caffeine may reduce production of breast milk, and decrease its iron concentrations, causing infant anemia!

Additionally, the infant may experience fussiness, jitteriness, and poor sleep patterns. If the infant shows signs of caffeine sensitivity, the lactating mother should significantly lower the caffeine intake.

Preterm infants and infants younger than 6 months are more vulnerable to caffeine. They metabolize it slowly. But, infants older than 9 months metabolize caffeine at the same rate as adults.

Hence, the maximum daily intake of caffeine for lactating women is 200 mg. Consuming this amount of caffeine is considered safe for breastfed infants.[4]

Certainly, pregnant and lactating women should consult their physician before consuming any amount of caffeine.

Last, pediatricians recommend that children under 12 should consume no caffeine. There is no proven safe dose of caffeine for children. Moreover, children older than 12 years and teenagers could consume small amounts of caffeine. But, the maximum safe dose is only 100 mg. This amount is found in two cans of soda.[5] 

How much caffeine do we consume?

About 85% of adults in the U.S. regularly consume caffeine. It’s estimated that the average daily intake of caffeine is about 180 mg. Two cups of coffee provide this amount of caffeine.

The average yearly intake of caffeine in the U.S. is 3.1 kg. The U.S. ranks 22nd. Finland and Norway are at the top of the list. Adults consume 9.6 and 7.2 kg of coffee on average per year, respectively.

Moreover, about 75% of U.S. children and teenagers consume moderate amounts of caffeine. Actually, children 9-13 years old consume about 26 mg of caffeine a day on average, while teenagers consume about 61 mg.

Adults get caffeine primarily from coffee and tea, while children get it from soda, energy drinks, and chocolate.

Side effects of exceeding the daily upper dose of caffeine

First, high caffeine intake may increase systolic blood pressure by 5-10 mmHg in people who don’t consume caffeine regularly.

Other mild adverse effects of caffeine may be anxiety, restlessness, insomnia, facial flushing, increased urination, muscle twitches, elevated or irregular heart rate, gastrointestinal upset, and sleep disturbances.

People sensitive to caffeine are more likely to have side effects.

Moreover, people with health issues should consult their physician before consuming caffeine. For instance, caffeine may have negative effects on people with cardiac arrhythmia, hypotension, myocardial infarction, electrolyte disturbances, anxiety, panic disorders, and sleep disturbances.

On the other hand, lack of caffeine may cause withdrawal symptoms. These symptoms usually begin 12 to 24 hours and peak in 1 to 2 days from last consumption. Caffeine consumption could stop these symptoms.

Foods high in caffeine to consume in moderation

Caffeine, either from food or supplements, is nearly 100% bioavailable.

Coffee, tea, and dark chocolate are the main dietary sources of caffeine.

Soda and energy drinks are also particularly rich in caffeine. In most cases, they contain synthetic caffeine or caffeine from guarana seed extracts.

Moreover, preworkout supplements contain huge amounts of caffeine. Most of them contain about 150-350 mg of caffeine per serving! As a rule of thumb, you should prefer preworkout supplements with the least amount of caffeine. You’ll find a wide variety on Amazon.

Children and teenagers consume high amounts of soda and energy drinks. It’s the main source of caffeine at these ages. As most energy drinks contain more than 100 mg of caffeine per serving, children should avoid consuming them. Just a can of energy drink may contain more caffeine than the maximum safe doses for teenagers and children!

Other products fortified with synthetic caffeine may be juices, chewing gums, water, cookies, candy, sauces, and syrups. Hence, parents should be very careful before buying any processed product. We should always check the ingredient list. Especially, if a product is marketed to provide energy or alertness.

How long does caffeine stay in the body?

When we consume caffeine, its effects start after 45-60 minutes and last up to 5 hours. Absorption rates are the same both for women and men.

Caffeine absorption is delayed when consumed with food. Also, alcohol decreases its clearance.

In contrast, smoking doubles the rate of caffeine clearance. This is probably a reason why smokers consume more caffeine.