Experts warn against some foods as cancer cases rise

KAMPALA - Uganda is facing an unprecedented rise in cancer cases, with 36,000 new diagnoses recorded last year — 4,000 more than two years ago. 

While experts at the Uganda Cancer Institute (UCI) cite multiple causes, including genetics, infections, and late diagnosis, growing evidence suggests that the food many Ugandans consume daily could be a silent killer. 

Medical experts are now warning Ugandans to closely monitor foods, especially vegetables such as dodo (Amaranthus dubius), ebuga (Amaranthus gracecizare), nakati (bitter tomato), sukuma wiki (collards), glossy red tomatoes, and onions, which they say are laden with pesticide residues. 

Fruits, especially those sold on Kampala’s streets, should also be eaten with caution. 
From contaminated grains to processed meats and pesticide-laden vegetables, the presence of carcinogens in everyday food is raising serious public health concerns. 

Experts warn that unless urgent interventions are made, Uganda will continue to see a surge in preventable cancer cases. 

UCI has seen a doubling of cancer cases over the past decade, with an overwhelming 80% of patients presenting at advanced stages.

The diet factor 

Dr Nixon Niyonzima, the head of research and training at UCI, said the high burden of cancer in Uganda is driven by multiple factors — including diet. 

“There is no doubt that food is playing a role in this crisis. Many people are unknowingly consuming unhealthy foods daily, such as burgers, sprayed vegetables and other processed foods,” he told New Vision. 

“The problem is that food safety regulation is weak and people do not have enough awareness about which foods put them at risk,” Niyonzima said. 

He said three major sources of cancer-causing substances in Uganda’s food supply chain include aflatoxins in grains, chemicals in processed foods and pesticides in fruits and vegetables. 

Aflatoxin is a deadly toxin produced by mould that grows on maize, groundnuts and other grains stored in poor conditions.

Aflatoxin menace 

Aflatoxin exposure, Dr Noleb Mugisha, an oncologist at UCI, said is strongly linked to liver cancer, a disease that is becoming increasingly common in Uganda. 

“Liver cancer cases have been rising sharply and aflatoxin is a major culprit. Unfortunately, many Ugandans rely on maize as a staple food. If it is not properly dried and stored, it becomes contaminated and once it enters the food chain, it is almost impossible to eliminate,” he said. 

Earlier this year, President Yoweri Museveni announced plans to issue an executive order banning the sale of contaminated and poor-quality groundnuts. 

Museveni said medical experts had linked these products to the rise in deadly cancer affecting Ugandans. The cancer, he added, was largely attributed to aflatoxins and toxic substances introduced into food products during farming, transportation and storage processes by farmers and dealers who do not follow proper standards. 

A 2023 study by the National Agricultural Research Organisation found that over 60% of maize and groundnuts sampled in Uganda contained aflatoxins at levels exceeding safe limits. 

Many of these products end up in local markets, schools, and even relief food for vulnerable populations. 

“The most disturbing part is that aflatoxin exposure happens over time. So, people do not realise they are being poisoned. By the time liver cancer is detected, it is often too late,” Mugisha said. 

Dr Daniel Kamara, a nutritionist from Bwindi Community Hospital, said tomatoes, especially imported ones, have also amplified the cancer threat among Ugandans. 

“Groundnuts aside, we have tomatoes that can be on the market for up to two months after harvest, mostly imported ones. But which fresh tomato lasts that long? These are chemicals added to preserve them and they are dangerous to our health,” Kamara said.

Medical experts have urged Ugandans to wash vegetables with vinegar.

Processed meat 

Mugisha said another major dietary risk factor is the rising consumption of processed and red meats. 

The World Health Organisation, Mugisha said, classifies processed meats — such as sausages, bacon and ham — as Group One carcinogens, meaning they have been scientifically proven to cause cancer. 

“Processed meats contain preservatives like nitrates and nitrites, which react in the stomach to form cancer-causing compounds. We are now seeing more cases of colorectal cancer, even among younger patients,” Mugisha said. 

With fast-food chains expanding in Uganda and processed meats becoming more accessible, Niyonzima said dietary habits are also rapidly changing. 

“Many Ugandans, especially urban dwellers, are consuming more grilled, fried and heavily processed foods that increase cancer risk. We recorded 3,800 cases from the central region, which is more urban-dominated, accounting for 50%. The remaining regions each contributed 20%. This data suggests that patients in the central region are exposed to more cancerous risks, but also have better access to cancer care,” Niyonzima said. 

While fruits and vegetables are essential for good health, experts warn that unsafe farming practices are contaminating these otherwise nutritious foods. 

Many farmers in Uganda, experts said, use excessive pesticides and chemical fertilisers, some of which are linked to cancer. Kamara said the growing evidence of pesticide residues in local produce is a key indicator of cancer risk. 

“Many farmers are using banned or highly toxic pesticides, often without proper training. These chemicals do not just wash off with water. They accumulate in the body over time, increasing the risk of cancers like leukaemia and lymphoma,” he said. 

A 2024 study by the Uganda National Bureau of Standards found that nearly 40% of sampled tomatoes, greens and fruits contained pesticide residues above acceptable limits. 

One of the biggest challenges in tackling unsafe food, Kamara added, is the lack of strict enforcement of food safety regulations. While Uganda has food safety laws, experts argue that implementation is weak due to limited resources and corruption. 

“The Uganda National Bureau of Standards is supposed to test food products before they reach the market, but they are understaffed and underfunded. Many substandard and contaminated foods still make it to consumers,” Kamara said. 

Cancer cases in Uganda, Niyonzima said, have surged, with 36,000 new cases registered last year, exceeding the estimated 33,000 annual diagnoses. UCI in Mulago handled 7,945 cases, while the regional cancer centre in Mbarara treated 1,400. 

Dr Jackson Orem, the executive director of UCI, emphasised the institute’s commitment to revolutionising cancer care in Uganda. “We are not just treating cancer; we are reshaping the future of cancer care in Uganda and the region,” he said.

Way forward 

Dr Noleb Mugisha, an oncologist, urged Ugandans to take personal precautions to reduce their risk of consuming cancer-causing foods:

• Avoid mouldy foods: Aflatoxins in poorly stored grains and nuts are highly toxic. Experts recommend buying maize flour from reputable sources that test for contamination. 

• Reduce processed meat consumption: Opt for fresh, lean meats and explore plant-based protein sources. 

• Minimise pesticide exposure: Wash fruits and vegetables with vinegar or baking soda and peel root vegetables when possible. 

• Support local organic farmers: Purchasing from farmers who use minimal chemicals can encourage healthier farming practices.