Published on 06/10/10

Scientist links African HIV, cancer to diet

By Sharon Dowdy

A University of Georgia scientist has discovered a connection between HIV incidence in Sub-Saharan Africa countries and the amount of corn people consume there.

While studying the role diet plays in infectious diseases, Tim Williams, an agronomist with the UGA College of Agricultural and Environmental Sciences, discovered that in nations where corn is a major part of diets the number of HIV infections is higher.

His findings were published in the May issue of the American Journal of Clinical Nutrition. U.S. Agency of International Development funded the work.

Contaminated corn linked to cancer, too

Using data from the World Health Organization and the Food and Agriculture Organization, Williams also found a link between eating toxin-prone crops and the number of liver and esophageal cancer cases.

He found that HIV and esophageal cancer deaths were significantly related to corn, or maize, consumption. In contrast, liver cancer deaths decreased with less maize consumption, perhaps because HIV dominated the anticipated consequences of the toxins that promote liver cancers.

“Good quality corn is unlikely to be the reason for this HIV-maize connection,” said Williams, a third-generation African who now directs the Peanut Collaborative Research Support Program on the UGA campus in Griffin, Ga.

“Contamination of their corn is believed to make Africans more vulnerable to infection,” he said.

Two toxins attack corn

Corn is prone to two toxins, fumonisin and aflatoxin, which can attack crops in the field or during storage. In the U.S., corn, peanut and other susceptible crops are inspected and tested for such toxins.

But in developing countries where people rely on these crops as primary food sources, proper testing to protect people from consuming contaminated crops is often skipped until acute poisoning results in deaths.

“In developing countries like those in Africa, a farmer may have a few bags of grain, and to use a significant amount to test for toxins is a high cost to assure quality. And then, by the time it’s analyzed, the farmer has sold the grain, and it’s been eaten,” Williams said.

Aflatoxins can cause a deficiency in protein, vitamins and minerals and suppress immunity, he said. Fumonisins are a group of mycotoxins found most often in corn.

“The discovery that fumonisin may be promoting HIV came as a surprise, but there is some evidence that this toxin increases the porosity of membranes which would increase the risk of becoming infected,” Williams said.

Ten-year study

For the past 10 years, Williams has lead a multi-university research effort studying how food toxins associated with cancers can also cause susceptibility to infectious diseases.

“I first thought I’d find a solution to liver cancer in the developing countries,” he said. “Liver cancer kills a significant number of people in Africa, but the cancer aspect was soon replaced in priority by the other effects on health associated with nutrition and immunotoxicity.”

If the theory is right, improving corn quality in Sub-Saharan Africa could significantly reduce HIV transmissions in the region, he said.

Toxins can be removed

And doing it may be relatively easy. Fumonisin can be removed from foods in a number simple ways, he said. Addressing the aflatoxin issue is also technically simple, but requires people to think outside the present regulatory box.

Williams’ team hopes to manage the toxin by adding a very cheap binding agent to protect consumers from being poisoned by their food rather than depending on more expensive testing methods.

“By addressing aflatoxin differently, we should be able to reduce all infectious diseases, and improve general nutrition,” he said. “Existing interventions work with difficulty in Africa, and they are more of a burden to the people.”

Farm techniques are preventative measures

Controlling insects, adding fertilizer, harvesting correctly and irrigating corn are all prevention methods used at the farm level. Storing crops in a cool, dry area helps, too, he said.

Most of these steps are costly for small farmers and not easily applied in developing countries. More research is needed to form a proper intervention strategy.

“It’s taken us 10 years to get this far, and when you start doing large-scale human trials, you need of a lot of funding,” he said. “Since the effects are usually deferred, or manifest in other illnesses, little attention has been paid to contamination, until now.”

Sharon Dowdy is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.

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