Most L-theanine supplements contain around 200mg, but there is no conclusive research that says just how much you should have. Drinking tea is generally safe for most people, and there have been no reports of overdose or side of affects of L-theanine.
However, it’s worth keeping in mind that many L-theanine supplements may contain caffeine, so its worth following the same guidelines as caffeine (400 mg)7.
Like caffeine, it is thought that if you consume excessive amounts of L-theanine you may experience:
- Nausea
- Upset stomach
- Feeling irritable
It would be considered best practice to consider your L-theanine intake and consult your doctor if you are:
- Pregnant or breastfeeding
- Have low blood pressure
- A child under 16
Summary
- Generally, for healthy adults there are no known side effects of L-theanine.
- Drinking tea is and L-theanine caffeine supplements are known to be safe, however its probably safest to follow the same guidelines as caffeine (400mg per day)8.
- Extreme amounts could cause sickness
- If you’re pregnant, have low blood pressure or have any concerns then you should consult your doctor.