Beri beri is a nutritional disorder which is due to the deficiency of vitamin B1 also called thiamine.Thiamine is necessary in the formation of energy molecules and it is involved in the breakdown of energy molecules such as glucose and is also found in the membranes of the neurons.More severe deficiency of Vitamin B1 causes beri beri and also affects the CVS and causespoly neuritis . In less severe deficiency, nonspecific signs include malaise, weight loss, irritability and confusion.Its phosphate derivative like thiamine phosphate is necessary for the catabolism of the glucose and amino acids.Yeast and pork are the most highly concentrated sources of thiamine.Some source are cereals,oatmeal, flax and Sunflower seeds, brown rice, whole grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver (beef, pork and chicken) and egg.
 
There are two types of beri beri:Dry beri beri which affects the cardiovascular system while dry beri beri affects the nervous system and causes the wernicke korsakoff syndrome.

The main cause behind the beri beri is deficiency of vitamin b1 So, an alcoholic can also develop it as there is decreased absorption of vitamin B1
 

It is in those areas also where there is available of mainly polished rice which is very low in thiamine content
 

Gastric bypass surgery It is more common in Asian countries where the white rice is a staple food.
 

It can also occur in breast fed infant when the mother's milk is lacking in thiamine.