Sunday, June 13, 2010

Study finds that as per capita maize consumption in sub-Saharan Africa countries rose, so did HIV transmission rates

There are large variations in HIV transmission rates between African social groups and nations. These differences have been the focus of significant research to understand the epidemiology of the disease and to develop interventions against the spread of the disease. Early research established links between social behavior and transmission rates. Many of these factors, such as male circumcision, faith, and partner concurrency have been further studied and proven important through detailed study, models, or clinical trials.

Food and nutritional factors have not received the same attention from a transmission perspective, but micronutrients in particular have been studied for their role in the progression of HIV. Mycotoxin contaminants in foods may also be important in the HIV epidemic. For example, chronic aflatoxicosis is associated with immune suppression and a reduction in essential nutrients and may result in deficiencies known to promote HIV progression.

In a new study published in the American Journal of Clinical Nutrition, Jonathan H. Williams of University of Georgia and colleagues examine whether corn contaminated with a fungus-derived toxin is helping to facilitate the transmission of HIV in sub-Saharan Africa. Using data from the World Health Organization and the Food and Agriculture Organization, the study found that as sub-Saharan countries' per-person corn consumption rose, so did HIV transmission rates.

In countries with a relatively higher percentage of Muslims – a factor linked to lower HIV rates – those with high per capita corn consumption had an estimated HIV infection rate of 291 per 100,000 people in one year. In contrast, the rate in those with low corn consumption was 74 per 100 000 people. Countries with both fewer Muslims than average and higher-than-average corn consumption had 435 HIV cases per 100 000 people.

The study also found that higher per-capita corn consumption correlated with a higher rate of esophageal cancer. Since fumonisin toxins have been linked to that cancer, the finding serves as an indicator that populations with high corn consumption were exposed to higher levels of fumonisin toxins. Thus, dietary sources of aflatoxin are a potential factor in the HIV epidemic.

Based on their statistical model, Williams and his colleagues estimate that if the "maize (corn) factor" were eliminated in sub-Saharan Africa, HIV transmissions could be cut by as much as 58%.
 In a region where an estimated 1.7 million people become infected with HIV annually, that would mean more than 1 million infections averted each year.

The study suggests that contamination might be prevented, for instance, by planting corn varieties genetically modified to be resistant to pests. It may also be possible to remove contaminants through certain milling technologies or by soaking the grain in water; fumonisin is water-soluble, so soaking and rinsing the grain or meal, then discarding the liquid may remove the toxin.

This likely to be the first study to find an association between corn consumption and HIV transmission rates in sub-Saharan Africa. Although it is biologically plausible that high fumonisin intake could make an individual more susceptible to HIV infection, these findings must be considered preliminary and need be backed up by further research.

See full article in American Journal of Clinical Nutrition May 19, 2010 as doi: 10.3945/ajcn.2009.28761.

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