A new study suggests that chronic periodontitis may cause a reaction in red blood cells and haemoglobin leading to the blood disorder anaemia. The research, published in The Journal of Periodontology, found that more than a third of people suffering from severe gum disease had haemoglobin levels below normal concentration. Following a six month course of treatment to improve their oral health, all patients has improved levels of red blood cells, haemoglobin and all other clinical measures used to assess the health of the blood. The research also suggested that women with severe gum disease had a higher risk of anaemia, compared to men. Less than three in ten men had anaemia, compared to over 4 in every ten women.