Fish oil supplementation in cancer patients. Capsules or nutritional drink supplements? A controlled study of compliance

Summary Background & aims Fish-oil, rich in Omega-3 long chain polyunsaturated fatty acids (n-3 LC PUFAs), may in high doses inhibit the development or progression of cancer cachexia. However, poor compliance to oral nutritional supplements is a well-known problem. We aimed to investigate acceptability and compliance to a nutritional drink with fish-oil compared to an equivalent dose of fish-oil administered as capsules in patients receiving chemotherapy for GI tract cancers. Moreover, we aimed to investigate, if there was a difference between a nutritional drink or capsules with respect to nutritional status and side effects. Finally, we aimed to examine, if n-3 LC PUFAs affect leukocyte and platelet counts, and markers of dose-limiting toxicities of chemotherapy. Methods We consecutively included 41 patients with advanced cancer in the controlled study. Patients were allocated (not randomized) to ingest either 10 capsules/day for four weeks or 400 mL/day of a nutritional drink with same dose of n-3 LC PUFA dose. Compliance was assessed by daily self-registration and n-3 LC PUFAs in whole blood. Side effects were assessed by 10 cm visual analog scales. Results Compliance and daily consumption of n-3 LC PUFAs were 96.4% (94.1–99.3) and 4.8 (4.7–4.9) g/day in the capsule group and 80.8 (55.4–93.6) % and 4.0 (2.8–4.7) g/day in the group, respectively (p ≤ 0.02). We found no differences between the groups with respect to changes in whole blood n-3 LC PUFAs, weight, nutritional status, acceptability or side effects. However, in the capsule group the whole blood n-3 LC PUFAs correlated negatively with the increase in nausea (rs = −0.39, p = 0.05), but not in the nutritional drink group. Nausea, reduced appetite and loose stools were of greatest importance for the deviations from recommended doses. The number of capsules had a negative impact on acceptability and compliance, whereas this was mainly related to taste and texture in the nutritional drink group. No changes in median thrombocyte or leukocyte blood counts were observed. Conclusions Fish oil in capsules appeared to result in better compliance compared to a nutritional drink with an equivalent dose of n-3 LC PUFAs. However, capsules and the drink did not differ with respect to the effect on nutritional status or side effects. Trial registration ClinicalTrials.gov Identifier NCT03751384 .