The present study, conducted on older cancer patients in palliative care with preserved functionality, demonstrated benefits in terms of improved nutritional status and QL in the group ingesting chocolate with a higher percentage of cocoa. IG1 showed an increased estimated polyphenol intake at the end of the intervention compared to CG and IG2. Several studies that used the values of the Phenol-Explorer databank or values measured by HPLC have reported a daily polyphenol intake ranging from 377 ± 15 to [29] 1756.5 ± 695.8 [30] mg/day in many countries [29–31]. However, all studies were conducted on healthy subjects, with no study on palliative care cancer patients. Considering that the mean worldwide intake of polyphenols is approximately 1 g/day, the present study detected a habitual daily intake of two to three times less, in agreement with the result reported in a Brazilian population study [29].
In addition, except for sodium, the intake of fibers, calcium and of all vitamins analyzed (A, B6, B12, C and E) was below recommended levels. With aging and progression of oncologic disease, modifications may occur in food consumption due to factors such as loss of appetite, sensory changes in gustatory and olfactory capacity, and social, emotional and economic aspects such as social isolation and depression, with a consequent reduction of the intake and absorption of micronutrients essential for health [32, 33].
However, the opposite was observed regarding sodium intake, which was excessive in all groups. This result has been associated with the increased consumption of processed and ultraprocessed foods by the population [34], with 80% of Brazilian older males and 61% of Brazilian older females habitually consuming higher than recommended sodium amounts [34].
Energy and protein consumption was lower than recommended in more than half the patients at the beginning and at the end of the study.
At the beginning and at the end of the study, CG showed lower calorie consumption per Kg than IG1 even with a higher BMI, a higher MAN score and albumin value and better functionality. Despite the difficulty in interpreting this finding, we believe that IG1 had a greater consumption per Kg as a form of compensation for its worse basal nutritional status. On the other hand, it has been demonstrated that reduced food intake or low energy intake is independently associated with weight loss in oncologic patients during progression of the disease [35, 36].
According to the MAN nutritional screening, most participants had an adequate nutritional status both at the beginning and at the end of the study. Previous studies have reported higher proportions of malnutrition among cancer patients in palliative care. However, those studies were more heterogeneous regarding the primary location of the tumor, nutritional assessment methods, and functionality [37–39]. This divergence may be attributed to the inclusion criteria of the present study.
At the beginning of the study, IG1 subjects had lower screening and nutritional assessment scores determined by the MAN tool and lower BMI and albumin values compared to the other groups. However, at the end of the intervention period, their screening score and MAN results were increased. Nutritional intervention can reduce the weight loss of patients in an advanced stage of cancer and improve their nutritional status [40].
No differences in body composition were observed here between groups, possibly owing to the short period of intervention. Nevertheless, it should be pointed out that changes in body composition in response to changes in the metabolic demand, physiological changes, aging and alterations due to cancer treatment are frequent among older adults receving palliative care and should be monitored [41].
Laboratory work-up demonstrated progression of oncologic disease. 8-OHdG levels were significantly increased in all groups, being possibly associated with the evolution of cancer patients [42].
After the period of intervention, IG1 showed an increase in the levels of the proinflammatory cytokine IL-6 with a concomitant reduction of the antioxidant defense compared to the other groups. These results suggest a worse clinical situation of these patients who already showed greater nutritional impairment at the beginning of the study. Systemic inflammation is associated with worse clinical outcomes, including reduced survival, of cancer patients [43]. GSH and vitamin C play a prominent role in cell protection against cytotoxic and carcinogenic substances [44].
Oxidative stress activates the inflammatory pathways that lead to the transformation of a normal cell into a neoplastic one, also affecting survival, proliferation, invasion, angiogenesis, and resistance to oncologic treatment [45]. Conversely, there is evidence that circulating IL-6 levels may also affect the antioxidant defense system [46]. During the final phase of the study, IL-6 levels were found to be significantly lower in IG2 compared to IG1. In agreement, the levels of MDA, a product of lipid peroxidation, were significantly reduced and GSH was increased in the white chocolate group.
We believe that the beneficial action of white chocolate consumption on systemic inflammation and the defense against oxidative stress may be the effect of some not yet studied component. The benefits of white chocolate intake were also observed in a study by OSTERTAG et al. (2013) [47] conducted on healthy subjects, showing that the consumption of 60 grams of white chocolate in a single intake contributed favorably to platelet activation and to bleeding time compared to bitter chocolate. Since white chocolate does not contain flavonoids, the authors suggested that other compounds such as milk serum protein may be responsible for antiplatelet effects [47]. Thus, we may consider white chocolate not to have a placebo effect, except for the evaluation of the polyphenol consumption.
Regarding the QL of the patients, IG1 progressed to higher scores in the functionality domain and subdomains, suggesting that the consumption of chocolate with a higher cocoa content was of benefit in terms of QL.
In a previous study, the authors observed low scores on global and functional health scales, with role functioning showing the worst evaluation, as well as high scores on the symptom scale [48]. In the present srudy, volunteers showed a good QL according to the global health scale and role functiong score, and the initial symptom score was low.
Few studies have analyzed the effect of dark chocolate consumption on QL, but some publications have suggested that supplementation with high cocoa chocolate can be of benefit [49, 50].
Strengths and limitations of the study:
This was a randomized, controlled study of nutritional intervention with chocolate. To date, we have not found any other studies that evaluated this intervention in older adults with cancer in palliative care. The limitations of the present study were a small number of subjects and a short period of intervention. However, this is an inherent difficulty of clinical studies in palliative care. We suggest that further interventions should explore the relations and the underlying causal mechanisms regarding chocolate consumption and its effects on the health and QL of older patients on palliative care.
The present results demonstrate that the consumption of chocolate with a higher cocoa content may contribute to improved nutritional status and functionality among older cancer patients in palliative care with > 70% prognosis of 30-day survival. The consumption of white chocolate was associated with an improvement of oxidative stress parameters.
Good adherence to the consumption of both chocolate types was observed during the study, this being a viable and pleasurable food of easy access contributing to the food supply and well-being of the patients.
Considering that food preferences are highly personal, we believe that nutritional support should also be adapted to the necessities, wishes and preferences of everyone in order to be effective and applicable to the reality of each one. In this respect, nutritional assistance can be an opportunity to aid the patients and their families during treatment.