Reframing Dietary and Nutritional Interventions for People with Dementia

1. Introduction

1.1. Malnutrition, Dehydration, and Outcomes in Dementia

In people with dementia, malnutrition and dehydration frequently occur due to reduced appetite, impaired swallowing, attentional deficits, changes in eating behavior, and difficulties adapting to the environment. These conditions are not merely accompanying symptoms; they are independent prognostic factors associated with functional decline, impaired immune function, delirium, worsening BPSD, increased risk of hospitalization, and mortality.

International guidelines for older adults consistently indicate that malnutrition and dehydration significantly increase the risk of functional decline and mortality (Volkert et al., 2019). More recently, guidelines specifically addressing nutrition and hydration management in people with dementia have been developed, clearly positioning nutritional care not as “supplementary care” but as “basic medical and caregiving intervention” in dementia (Volkert et al., 2024).

A critical point is that these findings do not claim that specific nutrients treat dementia. Rather, they demonstrate that malnutrition and dehydration act as conditions that discontinuously worsen the course of dementia through infection, delirium, falls, and BPSD. This relationship is schematically illustrated in Figure 1.

1.2. Limitations of Conventional Nutrition Education and Dietary Interventions

Against this background, various interventions—such as nutrition education, supplementation, and dietary planning—have been proposed. However, their reproducibility in real-world clinical and caregiving settings has not been consistently high.

The main reason is that conventional nutritional interventions rely on the following assumptions:

First, that individuals can self-manage food content and quantity.Second, that individuals can understand the importance of nutrients and adjust their choices accordingly.Third, that individuals can continuously make judgments at each meal.

All of these abilities strongly depend on attention, memory, and executive function, which are often compromised from the mild to moderate stages of dementia. As a result, nutritional interventions tend to become “correct but unworkable.”

This paper does not propose a new nutritional therapy. Rather, it aims to reorganize existing knowledge in a way that aligns with the cognitive realities of dementia and reconstructs it into a form that can actually function in practice.

2. Constraints in Dietary and Nutritional Interventions

2.1. Cognitive Constraints: Difficulties in Judgment, Choice, and Self-Management

In dementia, adjusting food intake, understanding nutritional balance, and making decisions among multiple options become increasingly difficult. In particular, decisions regarding “what and how much to eat” rely heavily on executive function and are therefore prone to early breakdown in dementia.

2.2. Behavioral and Environmental Constraints: Instability of Eating Behavior

Environmental changes, excessive stimulation, and experiences of failure during meals can easily trigger food refusal, selective eating, and BPSD. Excessive verbal prompting or instruction—even when well-intentioned—may amplify anxiety and confusion.

2.3. Nutritional Interventions as Implementation Failure

Thus, failures of nutritional interventions should be understood not as a lack of nutritional validity, but as a mismatch between design assumptions and patient characteristics.

3. Separating Active Ingredients from Excessive Burden

3.1. Core Active Ingredients in Dietary and Nutritional Interventions

Integrating the literature, the active ingredients of nutritional interventions for people with dementia can be summarized as follows:

• Securing adequate energy and protein
• Sustained fluid intake
• Prevention of acute deterioration due to malnutrition and dehydration

Figure 2 presents these active ingredients organized into a minimal, implementable model. Multinutrient interventions (e.g., LipiDiDiet) have demonstrated some suppression of functional decline in the prodromal stage of dementia (Soininen et al., 2017; 2021). One interpretation is that avoiding nutritional deficiency itself may be more important than specific components.

3.2. Excessive Implementation Burdens to Be Removed

In contrast, the following elements unnecessarily increase implementation burden:

• Detailed management at the level of individual nutrients
• Judgment and choice at every meal
• Self-recording of food intake
• Evaluation of achievement or intake levels

These elements should be intentionally removed.

4. Dementia-Adapted Dietary and Nutrition Intervention Model

4.1. Minimal Component ①: One Protein Item at Each Meal

At each meal, include one protein source (meat, fish, eggs, legumes, or dairy products) as the main dish. Quantity and nutritional calculation are not required. This is not intended to achieve a specific intake target, but rather to serve as an implementation guideline to avoid malnutrition.

Theoretical basis:

ESPEN guidelines indicate that protein deficiency in older adults and people with dementia is associated with functional decline (Volkert et al., 2019; 2024).

4.2. Minimal Component ②: Daily Fluid Intake of 1.2–1.5 L

Using water, tea, soup, etc., aim for a daily intake of 1.2–1.5 liters, divided across the day. Awareness of thirst is not assumed (medical judgment should take priority in cases such as heart failure or renal impairment).

Theoretical basis:

Dehydration is associated with delirium, hospitalization, and mortality risk (El-Sharkawy et al., 2015; Parkinson et al., 2023).

4.3. Minimal Component ③: A Decision-Free Eating Environment

Standardize menus, reduce choices, and maintain consistent meal times and locations. Meals are framed not as an individual management task, but as an environmental design task.

5. Implementation Protocol (Summary)

• Duration: Continuous
• Decision-maker: Caregivers and environment
• Recording: Simple checklist only
• Progression: Do not increase complexity

6. Implications for Research, Practice, and Policy

The novelty of this paper lies not in proposing new nutrients or therapeutic diets, but in reconstructing existing knowledge in a manner adapted to the cognitive and emotional constraints of dementia. Figure 3 illustrates the differences between conventional nutritional support and the dementia-adapted approach proposed here. In particular, it visualizes that implementation failure arises from design assumptions rather than nutritional content. The value of nutritional interventions should be evaluated not by cognitive outcomes, but by cost-related outcomes such as delirium, BPSD, hospitalization, and caregiving breakdown.

7. Conclusion

Dietary and nutritional interventions for people with dementia should be redefined not as treatment, but as control of conditions that accelerate deterioration. This paper presents a minimal, implementation-adapted model that can function sustainably in real-world care settings.