Dietary supplements and fatigue in patients with breast cancer: a systematic review

Systematic review of eight randomized studies (seven articles and one dissertation) including 932 women with breast cancer or breast cancer survivors. Participants were studied during chemotherapy, after curative treatment, or across mixed treatment contexts, with studies conducted in Brazil, the United States, Japan, and Malaysia.

Across the included trials, active regimens evaluated guarana extract, acetyl-L-carnitine, co-enzyme Q10, chlorella preparations, branched-chain amino acids, coconut oil, and vitamin mixtures. Intervention periods ranged from 3 to 24 weeks, and one study also tested a fatigue-reduction diet. Specific doses, frequency, and routes were not reported in the provided text.

Overall, several dietary supplements and one dietary pattern showed benefit for cancer-related fatigue, but the evidence was mixed across interventions. Five of the eight studies reported fatigue improvement, including trials of guarana extract, chlorella preparations, branched-chain amino acids with CoQ10 and acetyl-L-carnitine, and a fatigue-reduction diet; the review described the evidence for guarana and the diet as high quality. Coconut oil improved quality of life but did not reduce fatigue. No serious adverse events were attributed to supplementation, although guarana was associated with symptoms such as palpitations, nausea, insomnia, anxiety, and headache, and some trials reported grade 3 or higher events with acetyl-L-carnitine or branched-chain amino acids/CoQ10/acetyl-L-carnitine.

The evidence base was small and heterogeneous, with only eight studies and multiple different interventions, populations, and fatigue instruments, making cross-study comparison difficult. Dosing information was not reported in the provided text, and adverse event reporting was inconsistent. Several interventions were supported by only a single trial, and intervention duration was short overall at 3 to 24 weeks.