Our study showed that the risk of malnutrition or the presence of malnutrition was associated with the presence of depressive symptoms in the studied sample. We also observed a predominance of participants at risk of malnutrition and mild depressive symptoms in Brazil, with a 17.4-fold chance of presenting nutritional or depressive changes and a significantly weak and positive correlation. In Portugal, we observed a tendency towards the absence of changes in both nutritional status and depressive symptoms, with a high chance of not having changes (21.9 times) but with a strong positive and significant correlation.
These findings may be related to the profile of greater female predominance and higher levels of education found among the Portuguese participants. A study conducted by Ghimire, Baral (33), who used a profile similar to ours, suggested that this reality is explained by the fact that compared with men, women seek more access to health services in addition to placing a greater value on the preservation of their autonomy in daily activities and self-care, a fact also influenced by a higher level of education.
The presence of chronic diseases in our sample indicated to be predominant in both scenarios, although there was no prominence between them, which may explain the fact that Brazilians had a considerable chance of developing nutritional and depressive changes. In this regard, it was estimated that individual who live with chronic diseases have a greater tendency to experience reduced quality of life and life expectancy due to the negative consequences exerted by them(34). From a nutritional point of view, other studies have inferred that patients with chronic and malnourished diseases have a significant impairment in quality of life in addition to being more depressed and having lower life expectations(35, 36).
Regarding monthly income, in Portugal, some individuals did not have a regular income, and no participant had an income above the minimum wage, a situation opposite to that in Brazil, where participants had a higher level of income, despite their worse nutritional and depressive assessments. It is known that the quality of food is usually associated with how much income an individual or family has, and consequently, this aspect is inversely related to the risk of malnutrition/malnutrition(12, 13). Governmental measures for the selection and inclusion of these groups in income transfer programs, especially the Social Insertion Income (SII) in Portugal, can minimize the risk of malnutrition/malnutrition among elderly people, which aims to alleviate poverty, improve living conditions and health and encourage healthy habits(34). However, these aspects need to be addressed by the PHC in an educational and consistent way by promoting an orientation towards healthy nutrition consistent with the reality of each individual, family and community(19).
Other studies have shown that both low income and low education are associated with the risk of malnutrition and therefore may increase the risk of food insecurity(34, 37), which was one of our findings as well. Alvares and Amaral (38) included 3,552 Portuguese individuals; of these, 16.5% exhibited food insecurity in association with the same variables(38). Food insecurity is characterized as an individual who has a limited or uncertain possibility of acquiring food in a socially acceptable way or when the availability of food is compromised in relation to nutritional adequacy and safety(39). Thus, these factors may have contributed to the highest percentage of participants with poor nutritional status found in the two groups in our study.
Research carried out in Switzerland showed a higher percentage of individuals with depression, who were more prone to risks of malnutrition and frailty(40). This reality was indicated in the two countries we studied, but more clearly among Brazilians. Regarding this scenario, the importance of multidimensional interventions is increased to improve and/or minimize the nutritional deficits and depressive symptoms of the participants, as illustrated by successful past experiences in the Brazilian PHC scenario itself(9). However, the coronavirus pandemic, which began in 2019, is also projected to have effects on the general population, which includes elderly people, involving greater difficulty in circumventing the problem of depression in view of its substantial impact on mental health, which is generated by economic losses, deaths of family members, and other aspects affected in terms of behaviour, lifestyle and, consequently, nutritional status(4, 5).
Individuals in our study who were at risk of malnutrition had mild depressive symptoms in both countries, corroborating other findings in Taiwan, which also significantly associated the risk of malnutrition with depressive symptoms, where similar scales were used to measure these aspects, however with elderly people considered fragile(39). Our results may be associated with poor eating habits due to loss of appetite, which is aggravated by decreased food intake and lack of palatability and usually causes malnutrition with the risk of increased malnutrition when associated with depression(41).
In addition to showing an association and correlation between nutritional status and depressive symptoms, our study found a predominance of risk of malnutrition and mild depression in Brazil in comparison with Portugal. In a study conducted in Nepal, 10% of elderly people surveyed were malnourished, which accounted for 41% of the total effect of depression on quality of life, while depression had a 6% share of the total effect of malnutrition(33). Similarly, the Brazilians in our sample appeared to suffer the same greater influence of malnutrition on depression than vice versa. That is, we observed a proportionally higher percentage of Brazilians with strictly nutritional demands than those who had only depressive symptoms.
Evidence indicates that good eating habits can mitigate depressive symptoms(42, 43). In the study of Jacka, O'Neil (44), 32% of patients in two Australian hospitals who experienced moderate to severe depression and underwent a three-month dietary intervention showed significant improvements and remission of depressive symptoms. Therefore, the initiatives and interventions carried out in PHC units, which are gateways for the population, constitute a key strategy for health measures for active aging, which makes it possible to improve nutritional status and prevent malnutrition and depressive symptoms in medium and high complexity units. Active aging stands out as a concept of physical, social and mental well-being throughout life, that is, adopting healthy dietary, mental, exercise and leisure habits(45).
PHC, with integrated care and networks, therefore, is vital for the promotion of active and healthy aging, as well as for the resolution of basic health demands in both countries. Collective measures are essential, mainly because they increase user participation in the educational process, team involvement with the participant and work optimization(17, 21, 46). With the findings of two different scenarios, the importance of identifying changes in both nutritional status and mental health in the PHC scope is observed to improve the quality of life of the population towards healthy and active aging.
One of the limitations of this study was the sample size, especially of the group from Portugal, which suggests bias in the comparison between countries and impairment of the intergroup isonomy. In addition, the cross-sectional design of the study makes it difficult to establish causality. Thus, the inference power of our results is limited. Despite these obstacles, the methodological path we committed to was rigorously applied to seek the maximum similarity among the participants studied and, consequently, the greatest consistency of the data and its interpretations with respect to economic, social, cultural and cultural characteristics.