Caffeine: Friend or Foe?

Exercise Physiology Brisbane - 30 August 2022

Coffee: Friend or Foe

Do you enjoy a cup of coffee each day, or are energy drinks more your thing? The following blog article summarises the latest research regarding the health benefits and negative effects associated with caffeine consumption.

The average coffee consumption is around 135mg/day. One cup or one teaspoon of coffee has approximately 70-140mg of caffeine.

It takes around 45 minutes for the caffeine we have ingested to reach the blood stream, and approximately 2.5 to 4.5 hours to be metabolised. Smoking can increase the removal of caffeine from the blood stream, whereas pregnancy and some medications (included anti-depressants, antibiotics and contraceptives) slow removal.

  • Benefits of caffeine:
    Decreases fatigue, and increases alertness and reaction time
  • Decreases appetite and may reduce weight gain
  • May decrease risk of depression
  • 2-5 cups per day associated with reduced risk of Type II diabetes, some cancers and Parkinson's disease
  • 3-6mg/kg 1 hour before exercise may improve performance (effect vary based on genetics, daily caffeine habits, gender, fitness status and time of day)
  • Can positively influence gut microbiome and health metabolite production, and can increase intestinal motility and transit time (i.e., helps you poo)

Negative effects of caffeine:

  • >1200mg per day can cause agitation, severe anxiety, inability to sleep, elevate blood pressure, palpitations
  • Combined with alcohol can cause death
  • Avoid >200mg if pregnant (associated with lower birth weight)

Sources and further reading: doi:10.1001/jama.2021.21452; doi:10.3389/fspor.2020574854, doi:10.3390/nu12051287