HI. I went to give blood and was told my Haemoglobin was too low. The reading was 118. I am a 32year old man, 6 tall, 14st, fit healthy and active. I have felt tired, but put this down to working too hard. I eat well, and eat a lot of red meat and veg. Any thoughts on what could be causig this? And what to do about it? Thanks!