Which is the best tea for health?

All teas are made from the same plant genus  - Camellia Sinensis.The health benefits will therefore be broadly similar between teas.

The main difference between tea types is the flavour. This relates mainly to differences in plant type, cultivation and production techniques utilised. 

High quality teas are fresher then low quality ones. They are also far more refreshing and delicate. So quality loose leaf teas could be expected to be healthier to the degree that fresher vegables and fruit are considered to maximise their benefits over older fruit and vegetables.

This having been stated, there are some exceptions  to  the above:

• Green tea is believed to be more effective at reducing body sugar level. 
• Pu-erh tea is an exception tin that :
  
• There is a claim (not substantiated) that it can more effectively reduce body fat (related in part to its consumption in areas like Tibet where high fat meat  such as lamb and dairy foods are stables).
• Pu-erh tea, employing a  post-fermenting process (differs from all other tea types) increases its value/taste with age (like wine).