Every morning, millions of us reach for that familiar companion – a steaming cup of coffee or tea. But could this beloved beverage be both a friend and a foe? We’re demystifying caffeine’s effects on our health and redefining the right amount of daily caffeine for optimal well-being.
Use this guide to consider:
Seeking help for addiction or overdose treatment
Preparing your coffee another way to prevent cardiovascular side effects
Increasing or decreasing your caffeine consumption
whether you should start drinking coffee
But first, let’s consider the definition of caffeine.
What is Caffeine?
Defined as “a bitter alkaloid (C8H10N4O2) used medicinally as a stimulant and diuretic,” (Merriam-Webster), caffeine is the most consumed psychoactive agent in the world. This is not surprising considering the world drinks more coffee and tea than any other non-water beverage.
What is surprising is that caffeine is a psychoactive substance just like cocaine and marijuana, but in most cases is safe and may even be beneficial for health.
However, high amounts of caffeine, some sources of caffeine, and caffeine for certain populations can be harmful.
Caffeine is a Plant-Based Drug
Caffeine is found naturally in plants like cacao, yerba, tea leaves, coffee beans, kola nuts, and guarana berries. It’s added to soda, energy drinks, and tablets.
The amount of caffeine found in foods and drinks varies widely. This chart shows the number of milligrams of caffeine found in commonly consumed serving sizes of foods, drinks, and pills:
How Long Caffeine Stays in the Body
Caffeine affects different populations in different ways. For instance, caffeine will stay in the body of non-smokers double the amount of time than for smokers. Women who take “the pill” will experience caffeine symptoms about two times longer than other adults because it will stay in their systems for 6-14 hours. Infants, however, are affected the longest, with caffeine hanging around for over three days.
The length of time caffeine stays in a person’s body is also partially determined by their genetics.
Smokers: 1-2 hours
Most Adults: 3-7 hours
Women taking the “pill”/oral contraception: 6-14 hours
Pregnant women: 11-25 hours
Infants: 65-130 hours
Find out if caffeine is safe during pregnancy and breastfeeding here.
Dependence and Abuse of Caffeine
Caffeine can lead to an addiction and be abused. Although this is subjectively based on when an individual feels they are addicted and need help to stop consuming caffeine (there's no diagnostic code for caffeine addiction), withdrawal symptoms are physical and distressing.
According to a Swedish scientific review, “Caffeine affects the same parts of the brain as cocaine, but in completely different ways. There is evidence for caffeine withdrawal symptoms, and caffeine does act as a weak reinforcer, but neither effect is as pronounced as those associated with cocaine.”
Generally, caffeine is safe. However, there are clinical cases where caffeine has caused dependence and even abuse by individuals who consume too much or mix it with alcohol.
There is little treatment available for caffeine addicts, but they are advised to speak with their physicians if they need help.
Can people overdose on caffeine?
Yes, people can overdose on caffeine. However, it takes about 75-100 cups of coffee to O.D. to the point of a medical emergency. It is highly unlikely that a person would end up hospitalized or die from drinking too much coffee.
Most caffeine deaths are due to overdoses from caffeine powder, tablets or energy drinks. As little as 34 oz. of energy drinks can result in short-term heart issues. Separately, despite nightclubs’ high profits from selling alcohol mixed with energy drinks, it is not recommended to consume these cocktails.
If you suspect a caffeine overdose, call poison control (1-800-222-1222) or get the person to the hospital right away. PoisonControl.org warns, "Do NOT make the person throw up unless poison control or a health care provider tells you to do so."
Health Benefits of Caffeine
Coffee and tea are plant-based and contain nutrients that can benefit the body. Both are rich in antioxidants, polyphenols, and appetite-suppressing properties. Coffee has potassium, B vitamins, and chlorogenic acid. Tea has resveratrol and catechins, a type of polyphenol.
The Effect of Caffeine on the Heart
Research analyzed in the journal European Endocrinology provides evidence that three to five cups of coffee per day may reduce the risk of heart disease, coronary artery disease, stroke, and death from cardiovascular causes.
However, this is dependent on the way coffee is prepared. Coffee can actually harm the heart by raising LDL cholesterol if it is prepared as:
Scandinavian boiled coffee
Moka pot in small amounts
With added sugar or cream
It appears that for coffee to be safe and effective at reducing disease, it must be filtered. A home drip coffee pot or pour-over coffee preparation are the best choices.
For some people, coffee prepared in any way can increase blood pressure. This may be genetically determined.
The Effects of Caffeine on Diabetes
Studies suggest that regularly drinking caffeinated or decaf coffee or tea may decrease the risk of diabetes.
Unfortunately, for people who only drink coffee a few times a month, the risk of diabetes may actually increase.
For someone looking to make small changes to prevent diabetes, drinking coffee or tea consistently as a daily habit appears to be the key in these studies.
Can Caffeine Help with Weight Loss?
Depending on what the caffeine is mixed with and how much one drinks per day may determine whether it can support weight loss.
Studies reveal that drinking six cups of black coffee per day can help a person lose up to 5% of their weight.
However, coffee mixed with cream, whole fat milk, sugar, or alcohol can lead to weight gain.
Additionally, if caffeine is having a negative effect on your sleep, as we talk about in the blog Can’t Lose the Weight? 10 Simple Overlooked Behaviors to Change, hunger hormones will be triggered. Acting on hormone-induced cravings for high-fat comfort foods can promote weight gain.
Caffeine and Constipation
Because caffeine can speed up digestion, many people find a cup of coffee can support regular bowel movements. It may help break up a bout of constipation for some people.
Caffeine also works as a diuretic in those who aren’t accustomed to drinking tea or coffee every day. Over time, tolerance builds up and the diuretic (and dehydration) effect wear off.
Coffee and/or Caffeine May Reduce the Risk of Many Conditions
There are ongoing studies to look at whether caffeinated or decaf coffee or tea can have a positive effect on other conditions including cancer, liver disease, kidney stones, depression, Parkinson’s, and even gallstones.
Below is a chart that shows these conditions. Where the box has an “x,” studies suggest that beverage has shown possible reductions in disease risk or symptoms.
*Each study is designed differently with varying levels of confidence, quantity administered, and populations tested. No strong specific conclusions can be drawn yet.
Bottom Line: The Right Amount of Caffeine and Should You Start Drinking It
It’s not recommended that you add coffee to the diet if you don’t already drink it.
Until an individual builds up to drinking 3-5 cups of coffee everyday, there could be an increased risk for diabetes or high blood pressure.
Additionally, caffeine can interfere with calcium absorption.
It’s also dehydrating, as people who haven’t built a tolerance to coffee will urinate more due to its diuretic properties.
People with GERD, irregular heartbeats, and ulcers should avoid caffeine. (Cleveland Clinic)
Caffeine's stimulating effects can cause sleeplessness, jitters, anxiety, migraines, and even skin reactions like hives if there is a sensitivity to it.
Finally, caffeine can interfere with certain medications like Ephedrine, Echinacea, or Theophyline. (Mayo Clinic)
Established Coffee Drinkers
If you already incorporated caffeine into your regular morning routine, the recommendation is 3-5 cups of coffee per day to reduce the risk of disease and death. However, after 3 cups of caffeinated coffee (or 6 cups of caffeinated tea), switch to decaf.
The maximum amount of caffeine that humans should consume is 400 mg/day (24 oz. of coffee or 64 oz. of black tea).
Pregnant women are recommended to consume a maximum of 200mg/day of caffeine if it is already a part of their diet, however some research suggests that no amount of caffeine is safe for a growing fetus.
Up to 300mg/day of caffeine is safe during breastfeeding according to the strongest evidence available.
Children and Teens
Children and teens should limit caffeine intake to the occasional chocolate treat or cup of tea. The effects of caffeine are more pronounced in children and adolescents and can be dangerous. Most hospitalizations and deaths due to caffeine toxicity are in children due to accidental ingestion and young adults who mix caffeine with alcohol.
For less than the cost of a month’s worth of coffee, ZEST Nutrition can provide personalized nutrition sessions. Consider scheduling a telehealth appointment with a Registered Dietitian Nutritionist here. Evening and weekend appointments available.