This is the first study to evaluate an evidence-based telehealth intervention program designed specifically to improve the dietary intakes and behaviours of people with AMD. Overall, the intervention was delivered as planned for most participants with a total of 3.9 out of the intended four successful phone calls made per participant and an average total call duration of 75 minutes compared to the expected 80 minutes over the four months. The program was also well-received and appreciated by the participants and led to statistically significant and clinically meaningful improvements in dietary intakes over a 3-month follow-up.
Some of the key dietary recommendations for AMD published in the literature are to include: at least two serves per week of fish/seafood which is associated with reduced risk of early and neovascular AMD [3–5, 13, 36]; at least two serves per week of dark green leafy vegetables which is recommended to obtain the benefits of dietary carotenoids; and two to four eggs per week which has been linked to reduced risk of AMD progression, with eggs additionally being a bioavailable source of lutein and zeaxanthin[5, 37]. In our study, the intervention arm significantly increased their mean intakes to meet these particular recommendations immediately after the intervention. These improvements may be due to the program’s emphasis on AMD-specific dietary advice rather than general healthy eating advice such as increasing total vegetables and fruit intake.
At the 3-months post-intervention follow up, intakes of dark green leafy vegetables continued to be significantly higher compared to baseline intakes suggesting that this particular dietary modification may have been more feasible to incorporate and maintain in the diet than the other recommendations. However, mean fish/seafood intake at 3-months post-intervention continued to meet the recommended ≥ two serves per week and was approximately 0.3 serves higher than baseline. This difference is equivalent to a 30 g increase over the week, where a serve of fish/seafood is 100 g according to the Australian Dietary Guidelines. Although, we did not find this result to be statistically significant, research literature suggests that this increase has clinical importance for general health as a multi-cohort cross-cultural study investigating the diets of older adults in Australia, Greece, Japan and Sweden, reported that every 20 g increase in fish and shellfish intake was significantly associated with a 6% reduction in hazard of death, after accounting for ethnicity. Comparatively, our control arm’s mean fish/seafood intake increased by approximately 10 g (0.1 serve) to 1.82 serves per week which does not have statistical significance and less likely to be of clinical significance. This suggests that more targeted interventions than standard brochures may be needed to change dietary behaviour.
The study by Darmadi-Blackberry et al. also reported that every 20 g increase in legume intake was significantly associated with an 8% reduction in risk of death, irrespective of ethnicity. In our study, both the intervention and control arms increased their mean legume intake by more than 20 g (where a serve of legumes is 150g) at the 3-months post-intervention follow-up compared to baseline. However, the increase within the intervention arm was 25% higher than the control arm further supporting the effectiveness of the program.
In addition to improvements within the intervention arm, the program appears to have led to a difference in dietary intakes between study arms at 3-months post-intervention. The most notable difference being a significantly higher mean intake of nuts in the intervention arm (four serves per week) compared to the control arm (2.7 serves per week). The intervention arm also achieved better intakes of other food items compared to the control arm, however, these were non-significant. Interestingly, mean intakes of total vegetables and fruit were non-significantly higher in the control arm than the intervention arm at this follow up. Possible reasons for this difference could again be due to the program’s focus on AMD-specific recommendations rather than general healthy eating advice that was provided to the control arm or might be due to individual preferences for seasonal produce.
Overall, the positive dietary changes reported in this study may be the result of a culmination of factors. A study evaluating nutrition interventions amongst older adults reported that dietary modification was more successful in studies that included participants with a specific health condition. This may be due to increased motivation to manage the condition as most (60%) of our intervention participants were in the ‘preparation’ or ‘action’ stage of change at the start of the program. Furthermore, collaborative goal setting and regular contact with a health professional, which are incorporated within the 4 A’s approach of our intervention, have been shown to be successful nutrition education intervention components leading to better behavioral outcomes in older adults.[30, 39, 40] However, more significant dietary improvements may have been observed if our program limited its focus to one or two messages such as increasing intakes of dark green leafy vegetables and fish/seafood rather than also including messages around other food groups/items like nuts and legumes.
Strengths and Limitations
There are several strengths to this study. Firstly, this is a novel program designed to specifically improve the dietary intakes and behaviours of people with AMD and was tested using the “gold standard” RCT study design. Secondly, this program involved a collaborative effort between accredited practising dietitians and experts in the field of AMD (retinal specialists and epidemiologists) to provide evidence-based care. Thirdly, this program incorporates a telehealth component which is particularly suited to study participants who were typically older adults with functional limitations (vision and mobility) and other pre-existing health problems. Acceptance of a telehealth program is especially relevant in light of the current coronavirus disease-19 (COVID-19) pandemic which has emphasised the importance of telehealth services to provide safe and accessible healthcare to vulnerable subsets of the population. Our study findings therefore reinforce the advantages of telehealth programs and confirm that safe and effective dietary advice and counselling can be provided to older adults in this format.
However, no study is without limitations and we acknowledge that the results reported in this study may not reflect usual intake as the SDQ-AMD tool collects actual intake in the last week of a limited number of food items. In addition, this tool does not include a question about supplements use and therefore we are unable to report on participants’ use of the recommended Age-Related Eye Disease Study (AREDS) supplements for AMD. To overcome these limitations, the food frequency questionnaire, which collects usual dietary intake of 145 items and supplement use in the last 12 months, is currently being re-administered alongside the SDQ-AMD at the final follow-up (i.e. 6-months post-intervention). This data will then be compared with baseline data to provide further valuable insight into the usual dietary intakes and behaviour changes of patients with AMD.