According to researchers who looked at the food supplement intakes of 1081 cancer survivors, physicians should be encouraged to routinely discuss supplement use with their cancer patients. The researchers said data on this in Europe had been scarce until now.
The study, which came as part of the NutriNet-Santé cohort, found 62% of women and 29% of men used supplements with vitamins D, B6, C and magnesium being the most common.
In 18% of supplement users this equated to potentially harmful practices, such as the simultaneous use of vitamin E and anticoagulant or antiplatelet agents or the use of phyto-oestrogens in hormone-dependent cancer patients as well as the consumption of beta-carotene by smokers.
For 35% of the supplements consumed, subjects did not tell their physician. About 14% of the survivors started taking supplements after their diagnosis.
“The present study suggests that dietary supplement use is widespread among cancer survivors, a large amount of that use is performed without any medical supervision and a substantial proportion of that use involves potentially harmful practices,” the researchers wrote in the British Journal of Nutrition.
Patients associated the use of supplements with a healthier lifestyle, like having a normal weight, better diet and being a non-smoker.
The NutriNet-Santé cohort was launched in May 2009 with the main objective of assessing the relationship between nutrition and chronic disease risk as well as factors influencing eating behaviour.
The definition of ‘dietary supplement’ excluded clinical oral nutritional supplements, such as Renutryl or Clinutren, which were rich in energy and protein and given to undernourished patients to stimulate weight gain and avoid malnutrition. However it did consider both regular and medicinal supplements that contained things like vitamins and minerals but may be treated as pharmaceuticals in France.
US studies recorded higher supplement use among cancer survivors, but less told their physicians what they were taking.
The French study showed the main reason for not informing their doctor was simply because they were not asked.
The researchers said this may be because the physicians were unaware of the medical importance of supplement use in this context, the patients were unsure of their physicians reaction or the physician had limited time during consultations.
Collected through online self-assessment questionnaires, the research was conducted by the Anticancer Centre Léon-Bérard in Lyon, Avicenne Hospital in Bobigny, Rouen University and the Paris 13, 7 and 5 Universities in France and Laval University Cancer Research Centre in Québec, Canada.
Source: British Journal of Nutrition
Published online ahead of print, doi:10.1017/S0007114515000239
“Dietary supplement use among cancer survivors of the NutriNet-Sante cohort study”
Authors: C. Pouchieu, P. Fassier, N. Druesne-Pecollo, L. Zelek, P. Bachmann, M. Touillaud, I. Bairati, S. Hercberg, P. Galan, P. Cohen, P. Latino-Martel and M. Touvie