A Complete Guide to Caffeine

Caffeine is a stimulant that is found in many beverages and foods, and it is one of the most widely consumed substances in the world. From coffee to tea, energy drinks to chocolate, caffeine is present in many forms and is enjoyed by millions of people every day. However, caffeine can also be a source of confusion and misinformation, leading to questions about how much is safe to consume and what the potential health benefits and risks are. In this complete guide to caffeine, Dr Brian Fisher, Clinical Director at wellness app Evergreen Life, has shared his knowledge on the stimulant to help educate us on the effects of caffeine.

What effect does caffeine have on your body?

​Caffeine is absorbed into the body within around 45 minutes once consumed, remaining in the blood for anywhere between 1.5 and 9.5 hours after being broken down in the liver. Affecting the brain the most, caffeine helps to prevent feelings of tiredness and increased awareness as it blocks the effects of adenosine, the chemical responsible for making you feel fatigued.

What foods contain caffeine?

There’s a great many foods and drinks that contain caffeine, from the usual suspects such as tea and coffee, containing around 47mg and 90mg of the stuff respectively, to some options you may not consider, such as an ounce of dark chocolate containing around 24mg. On the fizzy drink front, a standard can of cola contains roughly 40mg of caffeine, while energy drinks usually contain 85mg. Even decaf coffee isn’t caffeine-free, containing about 4mg per cup!

Other than keeping you awake, what are some of the benefits of caffeine intake? 

​Researchers have found that caffeine can actually act as an antidepressant, with an 8% reduction in the risk of depression from daily intake. It has also been found to help with exercise, including improvements to muscle endurance, sprinting and jumping to name a few. Caffeine can also be a contributor in reducing the risk of type 2 diabetes and obesity.

What are the risks of caffeine intake?

​I really struggle with caffeine - it makes me really jittery and I get a rapid heart beat, even when only consuming small amounts - is that unusual?

While the scientific community at large says that caffeine has no adverse effects if consumed in moderation, there are still outliers to this fact. For example, some individuals may be genetically more sensitive to caffeine than others, and tremors, difficulty sleeping, and an irregular heartbeat have all been linked to excessive caffeine intake. It can also cause a short but dramatic spike in your blood pressure, so those who already suffer from high blood pressure should consult their doctor about what would be a healthy intake for them. For adults who aren’t pregnant and have no pre-existing health conditions, 400mg a day, or around 4-5 cups of coffee a day, isn’t associated with any dangerous side effects.