People with advanced cancer said food tasted better when they took the active ingredient in cannabis compared with sugar pills, a small Canadian study showed.

Cancer patients commonly report decreased appetite and changes in their sense of taste and smell that can lead to weight loss, anorexia, a poorer quality of life, and decreased survival, according to several short-term studies.

To explore whether tetrahydrocannabinol (THC) — the main psychoactive ingredient in cannabis — actually improves taste and smell perception and appetite, researchers in Montreal and Edmonton tested THC and placebo capsules in 21 adults with cancer. Of these, 11 were randomly assigned to THC and 10 to placebo.

The participants all had advanced cancer of all types except brain cancer, and they were all either being treated with chemotherapy or had in the past.

The subjects filled in taste and smell surveys before and after they took the pills twice daily for 18 days, recorded what they ate for three days, and were interviewed.

The majority (73 per cent) of those in the THC group said their enjoyment of food increased compared with 30 per cent of those in the placebo group, Prof. Wendy Wismer of the University of Alberta and her co-authors reported in the journal Annals of Oncology.

Appetite improved for 64 per cent of those in the THC group, with three patients showing no change and one gave incomplete data.

Among the placebo group, half had either decreased appetite, and 20 per cent showed no change.

There was no difference in calories consumed between the two groups but those in the THC-treated group tended to eat more protein and 55 per cent of them said savoury foods tasted better. Cancer patients often find meat smells and tastes unpleasant and avoid it, the researchers noted.

"Our findings are important as there is no accepted treatment for chemosensory alterations experienced by cancer patients," the study's authors concluded.

"THC treatment may hold multiple clinical benefits for cancer patients, beyond its indication as a treatment for nausea and its effects on appetite."

Wismer said she was "excited" about the possibility of using THC to improve patients' enjoyment of food, given it could improve their quality of life.

The study was funded by the Canadian Institutes of Health Research, the Alberta Cancer Board, Alberta Heritage Foundation for Medical Research, Natural Sciences and Engineering Research Council of Canada.

Solvay Pharma Inc. provided the drug, placebo, and third party monitor but was not involved in the study design or dissemination of the results.