When Huffman coding is inefficient?

Question

I have a question regarding the redundancy of Huffman coding. I know that for a general prefix code we have the following inequality:

$$ H(X) \le R \le H(X) + 1 $$

$R$ being the rate (average codeword length) and $H$ is the entropy. Based on this relation, how can we conclude that Huffman coding is very inefficient if entropy of the source is much smaller than 1 bit/symbol?