Caffeine is a stimulant and can ramp up an already overstimulated digestive and nervous system?! One of my first and basic recommendations for loose stools (especially in the morning), anxiety, difficulty falling asleep and unwinding, nervous tension, and restless energy is to remove caffeine from the daily equation.

Even “just one” coffee can have a significant impact on your physical and mental energy because of how different we are in how we metabolize caffeine.

The mean half life* of caffeine in healthy individuals is five (5) hours.

*The half life can vary from person to person by two to ten hours. (Half life refers to the time required for a concentration of a substance to be reduced by half)


These are factors that affect the ability of your body to metabolize caffeine:

Alcohol and smoking: alcohol consumption of 50 grams daily can increase caffeine half life by 72%. Smoking has been shown to stimulate caffeine clearance.

Prescription Medications: some medications like oral contraceptives (a.k.a The Pill) and anti-arrhythmic drugs, and calcium antagonists can increase caffeine half life.

Hormones: Caffeine clearance can slow down during the luteal phase of a woman’s menstrual cycle. Pregnancy can prolong caffeine, particularly during the third trimester.

Diet: Grapefruit juice can decrease caffeine clearance and prolong half life, whereas Brassica vegetables (e.g. broccoli, kale, cauliflower) and large quantities of vitamin C can increase caffeine clearance.

Genetic variability:The CYP1A2 gene influences how you metabolize caffeine. Individuals with the CYP1A2*1F polymorphism (one fast copy and one slow copy) are considered slow caffeine metabolizers.


By: Dr. Carly Wendler, B.A. SC., N.D