A new study in Nairobi says miraa (khat) chewing causes serious mental problems in humans.
The report comes weeks after Government scientists gave the herb a clean bill of health.
Published last week by the University of Nairobi (UoN) and University of Konstanz, Germany, it reported high rates of mental illnesses among heavy miraa users in Nairobi.
Heavy miraa users, the study says, are depressed, suffer from post-traumatic disorder (PTSD) and psychosis expressed as hallucinations and delusions.
PTSD is a mental health problem caused by very stressful, frightening or distressing events.
The new study led by Dr Michael Odenwald of the University Konstanz is published in the journal Social Psychiatry and Psychiatric Epidemiology.
Last month, scientists at the Kenya Medical Research Institute (Kemri) released results of a two-year study which had investigated the health effects of miraa chewing in Embu and Meru counties.
The results presented at the institution’s annual scientific conference in February, showed the herb has no negative health impact on users.
The Kemri study, which cost the Government Sh38 million, was supposed to counter grounds on which Britain, the US, France, Switzerland and Sweden banned the use of the herb in their territories.
“We subjected the data through finer levels of analysis which showed that miraa did not cause psychotic disorders,” lead researcher, Prof Charles Mbakaya had said.
The Kemri study which may have been good news for miraa farmers, traders and politicians in Meru and Embu could, however, have little if any impact on the international ban of khat.
First it has to be published, preferably in a reputable, peer-reviewed scientific journal, where it will be subjected to strong scrutiny from groups such as the Khat Research Programme (KRP) based at the University of Minnesota, US.
Over the years, KRP has either funded or collaborated in dozens of studies confirming the mental ill effects of miraa among users in Kenya, East Africa, the Middle East and Europe.
Most of the institutions and researchers in the new study are associated with KRP or their various studies on miraa have been funded through the group.
These include authors of the new study Dr Odenwald, Prof David Ndetei and Dr Abdulkadir Hussein Warsame both of the University of Nairobi and linked to the African Mental Health Foundation.
Dr Warsame also runs the Tawakal Medical Clinic in Eastleigh, Nairobi, which in a posting by KRP shows is helping Somali refugees in Nairobi with khat-related mental problems.
The University of Nairobi is indicated as one of KRP research sites in the region while collaborating with the Africa Mental Health Foundation and Tawakal Medical Clinic.
But over the weekend, Prof Ndetei refused to be drawn into discussing which of the two camps is right or wrong.
“We can’t go into such discussions because we have neither seen the data nor the methodologies in the Kemri study. Maybe until it is published in a scientific journal,” said Ndetei on phone.
What is true though is that KRP and its members have over the years accumulated and published dozens of papers on the ill-effects of miraa and are unlikely to be dented by the one-off Kemri study.
In 2014 for example, the same authors funded by KRP published a watershed study which has been the cause of intense pressure to ban the sale of local miraa in Somalia.