How much Caffeine should you have daily?

Nutrition, January 06, 2015

Coffee is a tricky subject. Some say it's bad for you, while others swear by it. In the end it comes down to what amount allows you to thrive.

The science points out that coffee is a complex beverage that has is the single biggest source of anti-oxident's for many people. Studies have proven that it can lower the risk of diabetes, and liver disease. Caffeine is the most commonly taken psychoactive substance in the world. The content per cup will vary depending on the type - it will range from 50mg (small home brewed coffee) to up to 400mg (large at starbucks).  Several studies have shown that 4 cups or 400mg is safe for most adults. Remember that there are other sources of caffeine besides coffee including soft drinks and chocolate.

If you drink too much coffee you will become restless, irritable, develop a fast heart beat, and it can upset your stomach. If you experience symptoms you should cut back on your intake or even cut out. Caffeine can affect people in different ways. You need to work out your individual tolerance. My wife suffers from tachycardia so we have decaffeinated beans in our household. I tend to have a decaf coffee every morning but always have a lemon water on waking first. 

If it does affect your sleep it's best not to consume coffee after 2pm in the afternoon. Don't drink coffee before a nap as It has been shown that even tiny amounts of caffeine  in your system will interfere with sleep quality. Even if you think caffeine dosn't effect your sleep - it will decrease your quality of sleep.  In Ben Greenfield's book (Beyond training, page 107 - for strength gains avoid excessive kcal restriction, excessive alcohol, soy, or caffeine)  he states that you should avoid excessive caffeine if attempting to build strength or put on muscle. In this case one coffee max a day should be your aim (maybe less).

In Brendan Braziers book "Thrive" (see book review under articles ) he describes coffee drinking as "uncomplimentary stress".He views it as a form of energy credit - and explains you will get enhanced stimulation now but will pay for it later when fatigue hits. If you suffer from excessive fatigue then cutting out caffeine is worth a try to see if energy levels improve. 

At present I will have 5 decaffeinated  coffees a week with my afternoon drink of choice being a green tea. I always have a caffeinated coffee before a key training session or a race as caffeine is a proven performance enhancer. most sports research recommendations show that you should consume 1-3 milligrams per kilogram (there are studies* that suggest 3-6mg/kg, there is NO benefit going over 9mg/kg and most people will suffer the negative performance side effects), so for a 68kg man that's 70-210 milligrams (between one small and 2 large cups of coffee. I would recommend going for the least possible as it can cause gastro issues. The caffeine is absorbed quickly and reaches it's highest blood concentration in around an hour (taking your coffee an hour before a race or key session is recommended) and can be maintained for several hours.

Lisa Moskovitz (reg Dietician & CEO of NY Nutrition group) recommends following your caffeine with water. Forgetting the water can lead to dehydration negatively impacting your skin, digestion, energy levels, nutrient absorption, and even joint health. Lisa also warns against artificial, non-nutritive sweetners such as sucralose and aspartame. They harm insulin levels, gut health, and can increase cravings for sweet things in general throughout the day. 

Samuele Marcora (exercise scientist at the University of Kent's Endurance research group) states a good case for the performance enhancement of caffeine in Alex Hutchinson's  book ENDURE (see book review under articles ) - caffeine has the ability to shoot down receptors in the brain that detect the presence of adenosine, a neuromodulator molecule associated with mental fatigue. This wards off mental fatigue, in turn keeping your sense of effort lower resulting in your ability to push harder and for longer.

As with anything when it comes to nutritional advice find out what works for you by experimenting with different amounts of coffee and see what enhances your ability to perform on a daily basis.


*Exercise endurance 1,3 and 6hr after caffeine ingestion in caffeine users and nonusers, Bell & McLellan, 2002, Journal of Applied Physiology.


Brad Dixon is a sports physio, coach, and wellness evangelist based at EVERFIT Physio & Coaching. His passion is promoting enhancing daily habits that nudge people towards potential and save the planet. His book ‘Holistic Human’ is available here - . The power is in our daily habits! Connect with Brad at, Facebook, Strava, Instagram (@everfitcoach), and YOU TUBE