Link between traditional beer, storage of maize and oesophageal cancer in the Eastern Cape revealed

14 Sep 2022

Researchers at Walter Sisulu University have found a link between the high incidence of oesophageal cancer in the province and the consumption of umqombothi (traditional beer). They say the risk of this type of cancer is increased by the consumption of umqombothi, coupled with a fungus found in inappropriately stored maize.

Umqombothi traditional beer, coupled with a maize-based diet — where maize is not stored properly — may be the leading cause of oesophageal cancer in the Eastern Cape. This is according to the latest findings of researchers at Walter Sisulu University.

Previous research has linked the consumption of traditionally brewed beer, often made with maize, to the high incidence of the disease, specifically among black men in the province.

The study, led by the department of human biology’s Prof Eugene Ndebia, continued previous work to find out why the Eastern Cape had an exceptionally high number of oesophageal cancer cases compared with other provinces.

“There are a lot of causes that have been brought forward for oesophageal cancer in the province,” Ndebia said, explaining that they had looked at the industrial pollution of the soil by factories and the possible contamination of vegetables with carcinogens.

“The other causes brought forward were tobacco and alcohol, but now the main reason we have found is that people with this type of cancer have a diet with a higher level of carbohydrates [in the form] of maize.

Maize meal storage

“Because the Eastern Cape has the highest percentage of people living below the poverty line, especially on the rural outskirts, people have found ways to preserve food by buying it in bulk and storing it.

“Maize on its own is not harmful as long as you buy it and use it within a reasonable time period. The problem is when you have stored it for a while that it starts to develop carcinogenic agents which become harmful to the oesophagus.

“It’s those chemicals that cause cancer, not the maize itself.

“You can buy maize meal and cook it today and that will be fine, but when you cook from the same bag of maize meal after a few weeks, it is no longer the same maize,” Ndebia added.

He said they had shown that fumonisins, a fungal toxin which is carcinogenic, is found in maize stored in poor conditions for up to four weeks.

“The way we store maize is also an important factor — when humidity and temperature [are] not controlled, this leads to the maize becoming contaminated with carcinogens. In rural areas the storage of food is usually not in a controlled environment,” he said.

Traditional beer

Umqombothi — a traditional beer made from maize — is also suggested to be one of the causes of oesophageal cancer.

“In the making of traditional beer, they are adding a lot of artificial components and those components can be carcinogenic… even the containers they use for beer during the fermentation and storage process have an impact. So, the problem is not the maize meal, but how you store it, how long you store it and what you add to it when you are cooking,” he said.

Ndebia concluded his hypothesis on how the cancer occurs, saying that if one’s diet is high in carbohydrates, this can increase reflux.

“Our research has led us to monitor a rare type of reflux which is not acid, also known as alkaline reflux,” he said.

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He said a surprisingly high number of patients seen by them had alkaline reflux, and they had linked this to patients with a diet high in maize.

“Research has shown that alkaline refluxes are very carcinogenic compared to acid refluxes. This may be why oesophageal cancer patients are usually diagnosed at an advanced stage of the disease, because nothing warns them to seek help early,” Ndebia said.

Research published in the South African Medical Journal in 2015 pointed to a possible link between oesophageal cancer and maize when researchers found that cases of this disease started increasing when traditional beer brewers switched from sorghum to corn.

Back then, researchers said studies were needed to link fumonisins to the increased incidence of oesophageal cancer in the province. DM/MC

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Maize meal storage

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