Guarana (Paullinia cupana) and Fatigue / low energy: evidence and sources

Objective The objective of the present study was to carry out a systematic review with a meta-analysis to assess evidence about the use of guarana fruit to manage fatigue in cancer patients. Methodology The data were extracted from the EMBASE, Scopus, MEDLINE, CENTRAL, and CINAHL databases, in any language, using the descriptors "neoplasms" and "Paullinia" or "guarana powder" and "placebos" and "fatigue". Searches were also conducted to identify any grey literature. Clinical studies with patients who presented cancer-related fatigue as a primary outcome and who used guarana as a dietary supplement were included. The risk of bias in randomized clinical trials was analyzed according to the Cochrane recommendations. The quality of the evidence was assessed using the GRADE system. For studies with the same types of tumors and treatments, meta-analysis was also conducted. Results A total of 383 studies were found and, of these, seven were included in the review, for a total of 427 cancer patients. The instruments used to analyze fatigue were the Brief Fatigue Inventory (BFI), the Chalder Fatigue Scale, the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-FATIGUE), and the Piper Scale. Some studies presented a low risk of bias for all the categories. Meta-analysis was conducted for three studies about breast cancer, which presented sufficient data. The use of guarana did not reduce cancer-related fatigue compared with placebo groups (mean of - 0.02 [95% CI - 1.54, 1.50]; p = 0.98) and the quality of evidence according to GRADE was very low. Conclusion Dietary supplements are used to improve cancer-related fatigue. The results of this review showed that the use of guarana was not superior to the placebo groups, pointing to the need for further studies with better methodological quality.

Guarana (GUA) seed extract, containing caffeine (CAF) and additional bioactive compounds, may positively affect mental performance, but evidence regarding exercise is limited. This investigation assessed acute GUA ingestion compared with CAF on endurance performance. Eleven endurance-trained noncyclists and cyclists (V˙O2peak = 49.7 ± 5.9, 60.4 ± 4.6 ml·kg·min-1) completed a double-blind, crossover experiment after ingesting (a) 100 mg CAF, (b) 500 mg GUA (containing 130 mg CAF), or (c) placebo (P) prior to 60-min fixed cycling workload (FIX) + 15-min time trial. Oxygen uptake, heart rate, respiratory exchange ratio, blood glucose, and lactate were not different (p ≥ .052) during FIX. A significant interaction (p = .042) for perceived exertion was observed at 50-min FIX with lower rating (p = .023) for GUA versus CAF but not compared with P. Work accumulated over 15-min time trial was greater (p = .038) for GUA versus P due to higher early (1-11 min) work outputs. Work performance favored (effect size = 0.18; 95% confidence interval [0.003, 0.355], p = .046) GUA (241.4 ± 39.9 kJ) versus P (232.1 ± 46.6 kJ), but CAF (232.3 ± 43.9) was not different from GUA (effect size = 0.19; 95% confidence interval [-0.022, 0.410], p = .079) or P. Postexercise strength loss was not attenuated with GUA (-5.6 ± 8.5%) or CAF (-8.3 ± 9.4%) versus P (-10.3 ± 5.1%). Acute GUA ingestion improved work performance relative to P, but effects were trivial to small and unrelated to altered substrate oxidation or muscular strength. Ergogenicity may involve central mechanisms reducing perceived effort with GUA (containing 130 mg caffeine). Due to issues related to identical matching of dosage, whether GUA confers additional benefits beyond its CAF content cannot be determined at present.

The present study aimed to systematically assess acute, dose-related behavioural effects of an extract of guaraná plant for the first time in humans. This double-blind, counterbalanced, placebo-controlled study (n=26) assessed the acute mood and cognitive effects throughout the day of four different doses (37.5 mg, 75 mg, 150 mg and 300 mg) of a standardised guaraná extract (PC-102). Assessment included the Cognitive Drug Research computerized test battery and Bond-Lader mood scales. Guaraná improved secondary memory performance and increased alert and content mood ratings. The two lower doses produced more positive cognitive effects than the higher doses. This research supports previous findings of cognitive improvements following 75 mg guaraná and provides the first exploration of different dose effects of guaraná in humans. The findings suggest that the effects cannot be attributed to caffeine alone.