Caffeine - All of Your Questions, Answered!

by Richard Santucci, RD, CDE, CPT

Last Updated: April 6, 2021

Food and drinks are to be enjoyed. Just thinking of our favorite coffee drink or tea can fill us with a little warm fuzzy feeling- especially on those colder days. But are there any risks with drinking caffeine? How much is too much? Are there any benefits to caffeine? Is caffeine a diuretic? Here we explore the many different aspects of this stimulating phytonutrient.

How Does Caffeine Affect the Body?
Caffeine is a stimulant, meaning it stimulates blood flow in the body. It does this by encouraging vasoconstriction, or the contracting of the blood vessels, which accelerates blood flow and can even make the heartbeat faster. With this capability, caffeine can stimulate blood flow to several organs in the body, including the brain, resulting in a temporary boost in mood and mental sharpness. Just think of that little burst of brainpower you get with that first cup or two of your favorite caffeinated drink in the morning.

How Much is Too Much?
Many of us can feel when we may have consumed too much caffeine, ranging from a few milligrams to many cups of coffee, but what should the daily intake of caffeine really be limited to? The FDA recommends consuming no more than 400mg/day. Depending on your preferred caffeinated beverage or food’s caffeine content, the quantity to consume looks different for everyone. While the FDA recommends consuming no more than 400 mg per day, you may experience side effects of excess caffeine far below this 400mg limit. Everyone responds differently to caffeine, so listen to your body and know your personal tolerance level when enjoying your favorite caffeine containing foods. The American Academy of Child and Adolescent Psychiatry states pediatricians currently advise children 12 and under to avoid caffeine and kids aged 12-18 to have no more than 100mg of caffeine a day. Here is a list of some of the most common caffeine-containing products with the average caffeine in mg and remember to check the label for the actual caffeine content:
Risks of Caffeine
While no set amount of caffeine will cause someone to experience negative effects, as discussed above, the FDA recommends limiting consumption to 400mg per day or less. How your body reacts to caffeine depends on your tolerance and how quickly your body metabolizes caffeine. Talk to your healthcare provider if you have any further questions. Possible side effects of excessive caffeine may include:
  • Insomnia
  • Jitters
  • Anxiousness
  • Fast heart rate
  • Upset stomach
  • Nausea
  • Headache
  • Unhappiness (dysphoria)

Is caffeine a diuretic?
One of the most common questions dietitians’ get asked about caffeine is if it is a diuretic. The answer is: the jury is still out. Multiple studies show that having 250-300mg caffeine per day does not cause excessive fluid loss outside of the regular fluid consumed in the day. If you have experienced increased urination after consuming a drink containing caffeine, it may be due to increased blood flow to the kidneys, stimulating urine production. Many studies suggest that the increased urine output experienced after caffeine consumption may be limited to those who irregularly consume caffeine.

A general rule for hydration is to drink about half your weight in oz with your weight measured in pounds, for example, 100oz for a 200lb person. However, individual fluid needs can vary based on your age, weight, health status, activity, and weather conditions, so talk to a dietitian for more personalized fluid requirements.

Caffeine is a stimulant that should be enjoyed in moderation within the limits of our body’s tolerance. It may be tempting to use caffeine as a crutch, as we can depend on short-term bursts of energy. If we get increasingly dependent on caffeine for energy and develop a tolerance to our regular caffeine intake, it can become less effective, even as we add more daily. Do your best to care for your body with love by enjoying nourishing foods, drinking adequate fluid, getting sufficient sleep and rest, and regular physical activity. Remember, don’t just sit there, be healthy! And enjoy your favorite caffeine-containing foods and drinks in moderation.

Disclaimer: This information is educational only and not providing healthcare recommendations. Please see a healthcare provider.


Richard Santucci, RD, CDE, CPT

Richard Santucci, RD, CDE, CPT

Richard Santucci has spent his whole life dedicated to health. After wrestling, boxing, & MMA, drained from overtraining, Richard spent the next 12 years creating a more plant-based diet program to rebuild his health. Richard is ready to help you live a healthier life with more energy and vitality and loves to help you plan meals for the family. In his free time, Richard enjoys playing music, disc golfing, gardening, and exploring local parks. His mission is to help people feel and perform better to enjoy a fun, fulfilling and productive life while respecting and caring for the planet.