Fast food outlets and restaurants that dispose of "abused" cooking oil to rogue companies which sell the "slow poison" to poor communities as a cheaper alternative to fresh oil, may be fuelling the health deterioration of HIV- positive people, a medical study has found.
And other local academic research has shown that the widespread abuse of cooking oils in food outlet kitchens is a public health risk that urgently needs to be tackled by the restaurant, fast food and oil industries.
Speaking in Durban on Wednesday, Prof Lodewyk Kock, head of the South African Fryer Oil Initiative at the University of the Free State, said the research findings published in the American Journal of Clinical Nutrition called for further urgent study.
Kock said in his article, published last month, that the study was performed by researchers at the University of the North West.
The study found that polyunsaturated fatty acid intake was adversely related to liver function in HIV positive asymptomatic subjects.
"Large amounts of heavily oxidised vegetable fats rich in n-6 polyunsaturated fatty acids, such as linoleic acid, have been distributed for many years by frying establishments as waste to poor black communities across South Africa," the study stated.
"These fats are nick-named 'fish oils' due to repeated frying of fish and subsequent fishy taste. We hypothesised in 2002 that these fats may adversely influence HIV-infected subjects . . . and may lead to oxidative stress and the progression of HIV and Aids," it said.
Kock said his initial research in 1994 into the abuse of cooking oil had shown that 30 percent of food outlets in Bloemfontein were guilty of the practice of abusing oil.
"Oil abuse is when you take cooking oil and fry it up to 190C and use it over and over and it starts to break down and become toxic. The more unhealthy it gets the more it is absorbed by the food," Kock said.
"One in eight frying establishments in South Africa abuse their oils and in Durban it's one in five," Kock said.
Since 1994 the university had analysed 10 000 samples of "fish oil" taken by the Department of Health from restaurants and fast food outlets around the country.
South African regulations regarding edible fats and oils stipulate levels of over 16 percent of polymerises triglycerides, a varnish-like compound, and over 25 percent of polar compounds are deemed "harmful or injurious to human health".
Kock advised consumers never to purchase cheap oil or brands that "appear over-night on the shelves" and to check the label for a low polymer content of around 2 percent.
Meanwhile, in an attempt to ensure oils no longer fit for human consumption do not get into the wrong hands one local fast food chain has pioneered the selling of used cooking oil to several bio-diesel companies.
Nando's Technical Director Jeff Bloch said the fast-food chain was the first in the country to implement a "sustainable oil initiative".