Doubts on DC subcarrier value?

[decode_done]

dc subcarrier

I am learning OFDM. I have one doubt on the DC subcarriers used inside One OFDM symbol. Everywhere i found DC subcarriers value will be set to Zero before IFFT during subcarrier mapping. why DC subcarriers are made zero? It can take any other value. Is it to reduce the transmitted power? because if u made it zero there will be no offset in the power.
Please clarify.

 

[sh3e]

ofdm dc sub-carrier

I think DC carriers which have frequencies near to zero are needed when we make filtering to this ofdm signal . u know that filter disturbs the frequencies at its roll off frequencies so, we put DC pilots at those frequencies with zero values to protect our data subcarriers, so we don not need to set any values to it to save power so making it zero values is better as I think.