Exploring the factors influencing nutritional literacy based on the socioecological model among patients with age-related macular degeneration: a qualitative study from China


Age-related macular degeneration (AMD) is one of the world’s three major blinding diseases1 that affect the macular area near the centre of the retinal structure, which leads to gradual loss of vision.2 AMD seriously impairs patients’ daily activities; it also causes negative emotions, which can significantly reduce the quality of life.3 Visual impairment is an independent risk factor that augments frailty,4 and it significantly harms a person’s health.5 AMD has high prevalence and blindness rates in the population.6 It is the leading cause of blindness in developed countries.7 In China, its prevalence among people aged over 70 is more than 20%.8 The condition is expected to grow as the global population ages.9

Both national and international guidelines state that nutritional treatment can delay the progression of AMD, reduce the risk of vision loss and improve patients’ quality of life,10 11 but few individuals follow these guidelines. An Australian study of nutritional interventions in AMD patients showed that only 38% of them took the recommended nutritional supplements while only 1% took them at the correct dosage.12 In another study, Hochstetler et al
13 investigated the use of nutritional supplements by AMD patients. They found that only 43% of patients reported taking the recommended dose of vitamins. The main reason for poor adherence was inadequate nutritional literacy.14 15

Nutritional literacy is the ability to obtain, understand and communicate specific nutritional information and make appropriate dietary decisions to promote one’s health.16 Adequate nutritional literacy is conducive to the promotion of patients’ positive nutritional cognition, correct nutritional skill practice, and improved dietary compliance and nutritional self-efficacy.17 18 Currently, studies of AMD mainly focus on the efficacy of nutrients and the evaluation of the effects of interventions19 20; studies of nutritional literacy are relatively rare. Therefore, we aim to use a qualitative approach to explore the factors affecting AMD patients. The socioecological model (SEM) is an integrated systemic, sociological and ecological approach that can be used to guide the study of the factors influencing individual health behaviours. The model suggests that people’s behaviours are influenced not only by intrapersonal characteristics but also by various social factors, such as interpersonal, institutional, environmental and policy.21 The intrapersonal-level contains personal knowledge, attitude and behaviour. The interpersonal level contains support from family, friends and peers. The institutional-level contains the support from organisations. The environmental level includes rules that influence how services may be the target of individuals. Last, the policy level contains domestic and international policies.22–24 Hence, by using semistructured interviews, this study tried to determine the elements that shape the nutritional literacy of AMD patients. Its results can inform the development of accurate strategies for nutritional-literacy interventions.

Materials and methods

Study design

This study used phenomenology and based on SEM to explore the factors influencing nutritional literacy in AMD patients.

Study setting and population

A purposive sampling method was used to select AMD patients in the Southwest Hospital of Chongqing Province, China. Potential participants were identified by ophthalmologists who were aware of the study and referred to the study team for screening. Eligibility was confirmed by the researchers using medical records, and eligible patients were contacted by telephone to explain the study. Written informed consent was obtained if patients agreed to participate. Patients should meet the inclusion criteria and be representative in age, sex, education and occupation. The inclusion criteria were meeting the diagnostic criteria for AMD recommended in the 2023 Chinese Clinical Guidelines for Age-Related Macular Degeneration,25 being aged 45 or above, and having a clear understanding of the study. The exclusion criteria were having other serious diseases, having another eye illness that affected the ability to see, and having cognitive, communication or mental disorders. All the patients volunteered to take part in the study, and they signed informed consent forms before being interviewed.

Data collection

Semistructured interviews were conducted with the participants. The principle of information saturation was followed. The study was conducted from May to June 2023. The outline of the study was developed based on the SEM. The interviews were conducted by PL, who trained in qualitative research at the school of nursing, and two senior qualitative researchers (WB and JW). The interviews were carried out in a quiet office of the ophthalmology department. First, the interviewer introduced herself and informed the interviewee of the content and methodology of the study. During the interview, the interviewer listened carefully, observed the facial expressions and body language of the participants, and recorded the conversation.

In a typical interview, the following questions were asked: (1) What do you think about the relationship between nutrition and AMD? (2) To what extent do you think you can manage your daily nutritional needs? (3) What kind of foods do you think are beneficial for people with macular degeneration? (4) Have you read about nutrients and AMD before? What kind of support do you need most? (5) What were the nutritional problems you encountered during your treatment and how did you deal with them? (6) What nutritional knowledge have you gained during your treatment, and how did you obtain it?

Data analysis

Within 24 hours of each interview, the first and second authors transcribed the recording and inserted the information concerning the participant’s expressions and behaviours in the transcript. After this work was completed, if there was missing content or ambiguities, the respondent was contacted via telephone for clarification. Then, the transcript was imported into NVivo V.12.0, and two researchers (the first and third authors) independently conducted thematic analysis according to Colaizzi’s seven-step method.26 Accordingly, we (1) carefully read all the interview materials; (2) extracted significant statements that were consistent with the phenomenon studied; (3) summarised and refined the meanings of these significant statements; (4) formed the themes, theme clusters and categories by finding common concepts and characteristics; (5) connected the themes with the research phenomenon to create a complete narrative; (6) constituted the essential structure of the phenomenon with the statements and (7) returned the results to the interviewees to verify the content’s authenticity. Then, the results were compared. Disagreements were evaluated by the corresponding author until agreement was reached. All data were anonymised in this process to avoid the researchers’ bias.

Patient and public involvement

The patients and the public were not involved in the study’s design, recruitment or conduct.


This qualitative study used the SEM to explore the factors affecting nutritional literacy in AMD patients. The results show that the multiple forms of stress that such patients have to deal with over a long period can lead to problems in their social ecosystems and ultimately limit access to nutritional literacy. Among these forms of stress, the problems occurring at the intrapersonal level are the most complex. They manifest as a series of unmet needs and negative emotions brought about by the impaired physical and mental health systems. The factors at the interpersonal and institutional levels are primarily related to the social-support system and the medical teams. At the policy level, the main issue is the gap between policy and implementation. The interaction of various factors shapes the nutritional literacy of AMD patients. Therefore, it is crucial for medical staff and family members to take effective action in order to meet the needs of patients and maintain the stability of their social ecosystems.

Intrapersonal-level factors

The results of this study suggest that health status, financial burden and lack of knowledge can affect AMD patients’ nutritional literacy. The participants with poor health status and nutritional knowledge were less active in developing nutritional literacy, which is consistent with the findings of other relevant studies.31 The majority of respondents said that due to a lack of nutritional knowledge, they ignored the type and dosage of nutrients suitable for AMD supplementation; hence, they were unable to make the right nutritional choices. According to Capacity, Opportunity, Motivation-Behaviour (COM-B) theory,32 individuals must have the correct physical and mental abilities to achieve a specific behaviour change, and their behavioural motivation must be adequate for a certain period. The lower the awareness of disease-related nutritional literacy, the more negative the attitude towards a nutritious diet and the weaker the motivation to adopt nutritionally appropriate behaviours. Furthermore, economic conditions affect nutritional literacy, especially when patients are poor. When buying food, patients with heavy economic burdens prioritise price over nutritional value, which affects their eating habits.33

The results also show that dietary preferences and nutritional self-efficacy affect patients’ nutritional literacy. For most of the interviewees, the higher the sense of nutritional self-efficacy, the greater the likelihood of adherence to proper nutritional behaviours, which is consistent with the findings of Tang et al.34 The unknown consequences of nutrient supplementation may make patients feel threatened, reduce their nutritional self-efficacy and hinder correct dietary habits. According to the health-belief model,35 whether one adopts a healthy behaviour or gives up a bad habit mainly depends on the perception of the severity of the risks and consequences as well as of the magnitude of the benefits and obstacles of adopting a correct behaviour. The results of one study showed that shared decision-making (SDM) can add value to patient care and that involving patients in decision-making can improve their motivation and adherence to treatment.36 Therefore, in future studies, we will invite AMD patients to participate in SDM on nutritional literacy to improve their nutritional self-efficacy and promote vision rehabilitation.

Moreover, dietary preferences also affect patients’ nutritional literacy. Most of the respondents said that their desire for vision improvement should not change their current lifestyles. Dietary preference is mainly determined by the interaction between genetic, sensory, environmental and other factors.37 There is evidence38 that the gradual introduction of new food items when done appropriately on multiple occasions, can influence food preferences. This suggests that hospitals and families should jointly develop nutritional-behaviour strategies to improve the dietary preferences of AMD patients.

The results of this study suggest that medical staff should strengthen the nutrition-related education imparted to patients, pay more attention to patients in poor health and with financial difficulties, and provide correct nutritional-literacy guidance. More attention should also be given to patients with poor eyesight in order to promote the formation and maintenance of good dietary habits. Furthermore, effective measures should be taken to improve patients’ nutritional self-efficacy, such as strengthening dietary knowledge and implementing precise interventions to improve nutritional literacy.

Interpersonal-level factors

The results show that family and patient support shape nutritional literacy. AMD patients face visual impairment and a reduction in physical activity so they tend to have negative feelings. Emotional, financial and social support can promote patients’ active participation in correct nutritional behaviour and reduce their psychological pressures; this can provide a sound basis for improving nutritional literacy. This finding suggests that healthcare providers should involve patients and their families in nutrition education, encourage them to adopt beneficial behaviours to achieve nutritional literacy, develop a family-centred nutritional-behaviour care model and build peer-support networks for patients.

The results also show that information found on the internet affects the nutritional literacy of AMD patients, as already highlighted by Ceylan et al.39 The convenience and efficiency of this kind of information can meet patients’ needs and strengthen appropriate nutritional habits. However, the knowledge vehiculated by social media is of mixed quality, which makes it difficult to distinguish between true and false information. Therefore, the relevant authorities should check the sources of content and try to limit the spread of misinformation. At the same, patients should strengthen their information literacy.

The support of medical professionals is another factor that influences the nutritional literacy of AMD patients. We found that the encouragement and guidance provided by health professionals could eliminate patients’ concerns about the risks of new nutritional behaviours and strengthen their motivation to change their diets. However, most of the participants said that they received little advice from medical staff. Therefore, nutritional-literacy education should be adjusted in the future. Multidisciplinary teams composed of doctors, nurses and dietitians should be set up to include nutritional literacy in routine examinations and dynamic assessments throughout the care process. At the same time, a learning guide should be formulated to provide specific suggestions and standards for medical personnel regarding the nutritional literacy of AMD patients.

Institutional-level factors

The results of this study indicate that doctor–patient trust and interdisciplinary-team consistency affected the nutritional literacy of AMD patients. The interviewees believed that low doctor–patient trust harmed nutritional literacy at the level of individual emotions and made it more difficult to access such literacy. Furthermore, the lack of consistency among interdisciplinary teams was also unhelpful. The patients followed more eagerly doctors’ suggestions when they had a high degree of trust in them. However, some doctors ignored nutritional knowledge when conveying medical information to patients, which indirectly affected their nutritional behaviours. Thus, it is necessary to strengthen the nutritional-literacy training of medical teams. Doing so can enhance trust in doctors and improve patients’ nutritional literacy.

Policy-level factors

The findings suggest that the gap between policy and implementation can affect nutritional literacy among AMD patients. The participants said that policy is authoritative and a key aspect of the development of nutritional literacy. However, current relevant policies emphasise the theoretical level of nutrients and disease-related diet, while they pay insufficient attention to the practical level that interests patients and do not effectively connect with healthcare institutions. This is not conducive to the improvement of patients’ nutritional literacy. Therefore, governments should formulate policies to promote nutritional literacy and the effective transformation of nutritional knowledge. It is necessary to find ways to enhance the nutritional literacy of AMD patients, such as encouraging individuals to participate in hospital training and using internet platforms to disseminate relevant information.


First, the participants were recruited from only one eye clinic in China, they were not representative of all patients with AMD. Therefore, future studies should involve multiple hospitals to interview patients. Second, only AMD patients were interviewed and other stakeholders were not involved in this study. Therefore, future studies should include more stakeholders to explore the factors influencing nutritional literacy. Third, interviewer bias may occur in a qualitative study. Although the bias is unlikely to be fully removed, we carried out an analysis with senior qualitative researchers to reduce this bias.


This study adopted a qualitative approach and conducted in-depth interviews with 15 participants to explore the factors affecting nutritional literacy among AMD patients based on the SEM. Healthcare professionals should pay attention to said factors and offer optimal solutions for the problems uncovered here. Furthermore, longitudinal follow-up research is needed to cover patients at different treatment stages. This will allow scholars to understand the dynamic-change process of nutritional literacy and modify patients’ nutritional behaviours.

This post was originally published on https://bmjopen.bmj.com