Study warns of rising health risks from reused cooking oil

Reused cooking oil also poses environmental risks, clogging drainage systems and polluting water sources./HANDOUT. 

As World Health Day is marked on April 7, concerns are rising over the reuse of cooking oil.

Experts are warning that the practice could be silently contributing to Kenya’s growing burden of non-communicable diseases.

A routine practice in many Kenyan households and informal eateries—reheating cooking oil—has come under scrutiny, with experts warning of serious long-term health risks.

A new study, “Assessment of Knowledge, Attitudes and Practices on Used Cooking Oil (UCO) Management in Kenya,” conducted by Muenzer Kenya in collaboration with Mohamed Karama, shows that repeatedly heating cooking oil alters its chemical composition.

This leads to the formation of harmful substances such as trans fats and toxic compounds linked to cancer, cardiovascular diseases and other chronic conditions.

Olivier Meganck, CEO of Muenzer Kenya, noted that health risks often begin with everyday practices.

“Repeatedly using the same cooking oil may seem harmless, but over time it can become a real health concern. Used cooking oil should not remain in the food chain,” he said.

According to the World Health Organization, non-communicable diseases account for about 27 per cent of all deaths in Kenya, with cardiovascular diseases and cancers among the leading causes.

The study revealed a worrying disconnect between awareness and behaviour. It showed that while most respondents acknowledged that reused cooking oil can harm health, many continue to use it multiple times, largely due to economic pressures.

The study also found that households and food vendors often rely on visible indicators, such as dark colour or smoke, to determine when oil is no longer usable.

“However, by this stage, the oil is already significantly degraded and potentially harmful,” the study showed.

Data from the Ministry of Health shows that Kenya is experiencing a steady rise in lifestyle-related illnesses, highlighting the need to address everyday dietary risks.

Dr Mary Kimani, a nutrition expert at the Ministry of Health, has previously said that small dietary habits can have cumulative health effects over time.

“We are seeing a rise in diet-related illnesses and repeated use of cooking oil is one of the overlooked risk factors. Public education and behaviour change are critical in reducing exposure to harmful substances,” she said.

Muenzer Kenya argued that awareness alone is not enough and called for practical interventions.

These include clearer guidelines for households and food vendors, as well as improved systems for collecting and safely disposing of used cooking oil.

“Knowing the risks is only the first step. What matters is acting on that knowledge—using oil responsibly and removing it from use before it becomes unsafe,” Meganck added.

Beyond health concerns, the study noted that improperly disposed cooking oil also poses environmental risks.

It can clog drainage systems and pollute water sources. However, when properly collected, used cooking oil can be converted into sustainable biodiesel, offering both environmental and economic benefits.

As Kenya joins the rest of the world in marking World Health Day, experts note that reducing exposure to preventable risk factors—including degraded cooking oil—could significantly lower the country’s disease burden.