27 May 2012

Tanzania: Aids Fight Trickier With Maize Consumption, Warn Experts

FOOD experts observe that the virus that causes AIDS, liver cancer and cancer of the throat has a relationship with eating a meal of maize-based food said to contain fumonisin.

Dr Martin Kimanya, Manager for Food Evaluation and Registration with Tanzania Food and Drugs Authority (TFDA) says samples of the 2005 maize harvest were collected from 120 households and examined for fumonisins and aflatoxins. Dr Kimanya conducted his study in Kilimanjaro, Iringa, Tabora, Morogoro and Ruvuma, chief producers of the crop in the country.

Information on whether the maize was sorted to remove defective (visibly damaged or mouldy) maize prior to storage and whether the damaged and mouldy maize or the non-dehulled maize was used as food was also collected. Further researches carried out by Jonathan H Williams, Jessica A Grubb, Jerry W Davis,Jia- Sheng Wang, Pauline E Jolly,

Nii-Ayi Ankrah, William O Ellis, Evans Afriyie-Gyawu, Natalie M Johnson, Abraham G Robinson, and Timothy D Phillips, show that Promotion of the HIV epidemic by aflatoxin is postulated but not yet established.

Sub-Saharan populations commonly consume food contaminated by mycotoxins, particularly aflatoxins predominantly found in peanut, maize, rice, and cassava and fumonisins, which occur primarily in maize. "The relation between cancer and food suggests that fumonisin contamination rather than aflatoxin is the mostly likely factor in maize-promoting HIV," the research says.

Fumonisin is one of the toxic substances called mycotoxins produced by various fungi under moist conditions and in right temperature. Humidity along the coastal areas is favourable to formation of such toxins. According to Dr Kimanya, fumonisin from dry areas like Tabora are more toxic.

They leave the grain apparently clean and good. "Since the majority of farmers in the country cultivate between 0.2 and 2.0 hectares per year mainly for subsistence with little surpluses for sale, one assumes that the main maize producers are also the main consumers," he said.

Epidemiological studies suggest an association between consumption of fumonisin contaminated maize and high incidence of esophageal (throat) cancer observed in former Transkei region of South Africa, North East Italy, China and Iran," he said.

Dr Kimanya who has done extensive study on maize as food source in the country, said the scourge of HIV, cancer of the liver (hepatocellular) and cancer of the throat (esophageal carcinomas) are related to consumption of mycotoxin-prone foods in sub- Saharan Africa.

Still, hulling (kukoboa) maize, gives the consumer a better chance of not getting fumonism, but reduces the meal's nutritional value by removing the germ of the grain. However, a sembe meal is faster absorbed by the body consequently producing energy faster. If you are HIV positive, progression to AIDS is five times faster with exposure to aflatoxin toxin, the food expert explains.

He adds that Americans have undertaken a study showing that exposure to maize contaminant of fumonisin is related to HIV infection. And chronic aflatoxicosis is associated with immune suppression. According to him, high level of aflatoxin exposure produces liver infection known as acute hepatic necrosis. Due to the tropical climate in Tanzania, maize is likely to be contaminated by these poisonous substances - mycotoxins caused by fungi, Dr Kimanya says in his research.

Studies, he adds, show that fumonisin can cause abdominal pain and retard the growth of the fetus. The level of this infection of the crop varies in areas with notable high amount found in Tabora, Iringa, Kilimanjaro and Ruvuma regions. However, preservation or storage and processing food items is crucial in maintaining their quality. Deep freezing food, he explained, does not alter much the food nutritional content.

Ms Wessy Meghji, a researcher in Food Techology with Tanzania Food and Nutrition Centre (TFNC) explains that the sembe flour gets into the body faster because of the absence of fibre known as roughage which takes longer to digest. But the fibre is important to the body. A medical report indicates that the main function of fibre in the body is to keep the digestive system healthy and function properly.

"Fibre aids and speeds up the excretion of waste and toxins from the body, preventing it from sitting in the intestine or bowel for too long, which could cause a build-up and lead to several diseases," the wire report adds. But many people, especially urban dwellers, use sembe mostly for its attractive look to the eye.

Shopkeepers appear to favour sembe too possibly from the economic point of view. "Shelf-life of flour of hulled maize (sembe) is longer than flour of whole grain maize, which is rich in nutriens and attracts micro-organisms which make it rancid," Ms Meghji explains. Supportive, Dr Kimanya says apart from the loss of the grain's germ, "The amount of carbohydrate in it is still the same as that of the whole grain.

The only difference is the absence of fibre which has immense value to the body." Dr Kimanya said the government was looking into how to fortify the flour of hulled maize with missing nutrients to make it rich again. "That will protect consumers of maize-based food from mycotoxins and still give them the nutritional value of the food," he explains. Moreover, says Ms Meghji, no one source of food has all the nutrients the body requires.

It is therefore advisable to eat a wide variety of food items to get a balanced diet. Dr Kimanya says small amounts of fumonisin or aflatoxin taken on a daily basis from various food sources can be neutralized by eating fruits and vegetable, which respectively have vitamin E and C. "Vitamin C is radical scavenger," he explains.

A free radical is an atom or a molecule that bears an unpaired electron and is extremely reactive, capable of engaging in rapid chain reactions that destabilize other molecules and generate many more free radicals. "The oxidative stress that oxygen-free radicals cause, is thought to be reason why our bodies age," a medical report says.

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