How much caffeine is too much?

If a caffeine kick is part of your morning ritual, you’re not alone around 80% of us take some form of caffeine each day. In the fast-paced modern world, our reliance on caffeine has only increased. But how exactly does this potent pick-me-up impact on our health and how much caffeine is too much?

Caffeine is absorbed rapidly in the human body, taking about 45 minutes to an hour to be completely absorbed. The effects of caffeine on human health have been very well studied, and though most of us consume caffeine to enhance concentration and wakefulness, it can have both positive and negative effects on many other aspects of our mental and physical health. Here are a few ways caffeine could have an impact on you:

1. Caffeine boosts athletic performance

Because caffeine works on the nervous system, it affects the way your body perceives things like maximum muscle power and physical exhaustion.

Just 100mg of caffeine (or a cup of coffee) before physical activity helps to increase endurance so that you can last longer while cycling or running before feeling fatigue. Taking caffeine can also change your pain thresholds so that you can push your muscles harder without experiencing distress.

2. Improves microbiome diversity

Your gut microbiome contains trillions of microorganisms. And having a diverse gut microbiome is associated with good health. Studies have found that drinking coffee is associated with increased abundance of certain beneficial bacteria, such as Lawsonibacter asaccharolyticus, and changes in the composition of intestinal microbiota.

ZOE’s PREDICT studies found that coffee drinkers tended to have more diversity in their microbiomes. One possible explanation has to do with the soluble fiber and prebiotic properties in coffee that feed beneficial gut bugs. 

3. Caffeine may heal damaged cells

Coffee is a good source of antioxidants, which are compounds that help prevent and repair damage to cells and genetic material around your body. 

Research has shown that coffee is a significant source of polyphenols, a type of antioxidant, in many people's diets. Polyphenols also help fuel your “good” gut bacteria.

However, individual responses to coffee consumption may vary, and moderation is key when incorporating coffee into a healthy diet. It is important to take note of some of the ways caffeine can negatively impact you if not careful.

1. Caffeine may disturb sleep

People who consume caffeine close to bedtime may find it harder to nod off due to its wakefulness effect. The good news is that it’s easy to prevent caffeine from disturbing your sleep by regulating when you choose to take in caffeine.

It takes about 2.5 to 4.5 hours for the average person to process half the amount of caffeine they ingest, and this half-life of caffeine changes with our lifestyles, smoking speeds up caffeine metabolism, while taking oral contraceptives can slow it down.

A good rule of thumb is to stop taking caffeine-containing food and drinks at least 6 hours before you usually go to sleep.

2. Caffeine can have a negative impact on mental health

Caffeine can impact mental health and anxiety in different ways depending on how much is consumed. In low doses, it may actually help to improve mood and reduce anxiety or depression, but taking too much caffeine can make people feel jittery or tense, so it’s best to check how you’re feeling before deciding on whether another coffee is the right call.

3. Caffeine addiction and withdrawal

Given the positive effects that caffeine can have as a stimulant, caffeine activates many of the same behavioural and neuropharmacological mechanisms that are activated by other reinforcers, including other drugs of abuse. A small percentage of the population develops a caffeine use disorder. The absence or reduction of coffee consumption in these individuals results in a caffeine withdrawal. You may want to cut back if you're drinking more than 4 cups of caffeinated coffee a day (or the equivalent) and you have side effects such as: Headache, insomnia, nervousness and irritability, fast heartbeat, muscle tremors, frequent urination or inability to control urination.

Some people are more sensitive to caffeine than are others. If you're susceptible to the effects of caffeine, even small amounts may prompt unwanted effects, such as restlessness and sleep problems. How you react to caffeine may be determined in part by how much caffeine you're used to drinking. People who don't regularly drink caffeine tend to be more sensitive to its effects.

In summary:

Caffeine affects us all differently, and we all have our own tolerance to its effects depending on our genes and our lifestyles. It’s difficult to gauge how much caffeine is too much, but as long as you know your limits, and avoid taking too many caffeine supplements, there’s no reason to fear that your caffeine fix is getting in the way of your health. In fact, there are many antioxidants and other compounds in coffee, so drinking a cup or two a day might well actually be good for you.