“According to our data, the elevated retinol levels are due to diminished renal function and not to better patient care with respect to vitamin A,” said Danquah. “Physicians should consider this in the future when assessing the vitamin A status of the population in sub-Saharan Africa.” The research team, which included researchers from the Institute of Tropical Medicine and International Health at the Charité in Berlin and the University of Science and Technology in Kumasi, Ghana, recently published its findings in the American Journal of Clinical Nutrition (Danquah et al., 2015, doi: 10.3945/ajcn.114.101345).
Paradoxically, the sub-Saharan African population is not only affected by malnutrition, but also increasingly from obesity-related diseases such as hypertension and type 2 diabetes. In the opinion of nutritionists, the reasons for this lie in the changed living and environmental conditions. Although the present-day diet of the urban population of Ghana is often high in calories, it tends to be one-sided. Therefore, obese adults can suffer from a vitamin A deficiency that, among other effects, can lead to impaired eyesight and a disturbed immune system.
To investigate the relationships between diet, high blood pressure, type 2 diabetes and vitamin A status in a Ghanaian population for the first time, the researchers examined 1,219 mostly female study participants around age 50. Of these, 197 were diagnosed with type 2 diabetes, 354 of the participants had high blood pressure, and 340 people suffered from both diseases. In addition to various clinical parameters, such as the retinol level in the blood, the scientists examined the body measurements of the participants and also checked their vitamin A intake through questionnaires.
Although all study participants consumed about the same amount of vitamin A in their food, the participants with high blood pressure had retinol levels that were elevated by about 21 percent. The retinol levels of the participants with both high blood pressure and type 2 diabetes were even increased by 38 percent. The majority of people with high blood pressure and diabetes were overweight. At the same time, the scientists observed that in the patients with higher retinol levels, the kidney function was impaired.
“Our observations emphasize the important role metabolic diseases play for the unresolved health problems in sub-Saharan Africa. That is why it is necessary to develop prevention and treatment strategies for these structurally weak and resource-poor regions that effectively and efficiently fight under- and over-nutrition. In this particular case the question arises whether high blood pressure, type 2 diabetes and its comorbidities should in the future be considered in order to better assess the vitamin A status of a person,” said study leader Danquah.
According to the World Health Organization (WHO), in sub-Saharan Africa the number of people with non-communicable diseases has significantly increased. These include, for example, type 2 diabetes or cardiovascular disease. About a quarter of the deaths in this region can be attributed to such diseases (Source: World Health Organization. Global status report on non-communicable diseases 2010. Geneva: World Health Organization, 2011). According to a report of the International Diabetes Federation, by 2035 the number of people with diabetes in this region will more than have doubled, from 20 million today to 42 million (International Diabetes Federation. IDF diabetes atlas. 6th ed. Brussels (Belgium):International Diabetes Federation; 2013).