Q: Can I drink too much green tea a day? And will it help with my diet?

A: Green tea is safe for most adults when used in moderate amounts.

It’s important to remember that green tea (and green tea extracts) contains caffeine. Caffeine is a mild central nervous system stimulant and can make you feel jittery, anxious or restless and may cause insomnia, stomach irritation, nausea, diarrhoea and frequent urination in some people.

Studies have shown that certain genetic predispositions make some people more sensitive to the effects of caffeine.

The recommendation for caffeine is 300mg or less per day, which is about 6 to 7 cups of tea. But remember to also count other sources of caffeine, such as coffee, chocolate and cola drinks.

Green tea contains small amounts of vitamin K, which can interfere with anticoagulant drugs, such as warfarin. There have also been some case reports of liver problems in people taking concentrated green tea extracts.

There is some evidence showing that green tea may assist with weight loss, but most studies only show very small effects, if any and findings are questionable at this point.