Wang obtained her PhD on 23 April at Human Nutrition & Health. She investigated the relationship between diabetes, tuberculosis and vitamin D deficiency in tuberculosis patients in the Chinese rural region of Linyi, Shandong. A large-scale epidemiological study among 6382 tuberculosis patients revealed that diabetes occurs three times as frequently among members of this group.
‘Diabetes may increase the risk of developing tuberculosis’, says epidemiologist Evert Schouten, Wang’s promotor. ‘This might be because diabetes suppresses the immune system, which makes people more susceptible to the tuberculosis bacterium.’ According to Schouten, it is difficult to make definitive statements based on this epidemiological study. ‘To get more details about cause and effect, we would have to follow a group for a prolonged time and investigate which people develop tuberculosis. But something like that is difficult to achieve in practice.’
Vitamin D deficiency
Blood tests in 461 tuberculosis patients revealed that nearly 80 percent had a vitamin D deficiency. Schouten: ‘This is probably caused by their diet not containing enough vitamins or due to lack of sunlight, which results in too little vitamin D being produced in the skin.’ Vitamin D ensures the proper functioning of our immune system, among other things. Treatment with vitamin D improved symptoms, but only in the group of patients who had both diabetes and tuberculosis.
In the past, patients would be put out in the sun at the sanatorium. However, that habit disappeared with the arrival of medication.Evert Schouten, Qiuzhen Wang’s promotor
Schouten: ‘To gain a clearer view of the effects of the treatment, we should do clinical trials that build upon this. Our study does indicate that vitamin D could help.’ According to Schouten, the relationship between vitamin D deficiency and tuberculosis is not entirely new. ‘In the past, patients would be put out in the sun at the sanatorium. However, that habit disappeared with the arrival of medication.’
Tuberculosis is a prevalent global public health issue, and certainly in China. With the increasing prosperity, the number of people in China that have diabetes is also increasing. The population suffers from what is called the double burden of malnutrition: on the one hand, there is undernutrition and vitamin deficiency, and on the other hand, unhealthy (over)nutrition leads to overweight and diabetes. Wang advised the Chinese government to screen for tuberculosis and diabetes and to consider setting up a vitamin D supplementation programme. These measures could help patients and prevent the spread of tuberculosis.