Summary and Critical Appraisal of “Dietary Diversity Contributes to Delay Biological Ageing” with Practical Applications.
A recent study by Liao and Li delves into how dietary diversity—the range of different foods and nutrients one consumes—may help delay biological ageing. With the global population ageing rapidly, understanding strategies that promote healthy ageing is critical. This study examines whether a more varied diet, as measured by the Dietary Diversity Score (DDS), is associated with slower biological ageing. Using data from over 22,600 participants in the National Health and Nutrition Examination Survey (NHANES), the study presents compelling findings on the link between diet and ageing.
Key Findings and Concepts
Dietary Diversity and Biological Ageing
Liao and Li used DDS to assess participants’ intake across five major food groups (grains, vegetables, fruits, proteins, and dairy) and evaluated biological age through advanced markers like phenotypic age and the Klemera-Doubal method (KDM). The study found that higher DDS was consistently linked to slower biological age acceleration, suggesting that a varied diet can help delay the effects of ageing. This association held true across all demographic groups, indicating that dietary diversity might be broadly beneficial.
Oxidative Stress as a Mediator
A key finding is that oxidative stress partly mediates the relationship between DDS and ageing. Specifically, participants with higher dietary diversity had lower levels of glutamyltransferase (GGT), an indicator of oxidative stress. Since oxidative stress and inflammation are closely linked to ageing, these results suggest that a diverse diet, rich in antioxidants and anti-inflammatory nutrients, could help mitigate the cellular damage associated with ageing.
Broader Health Benefits
The study’s findings align with previous research showing that dietary diversity reduces the risk of chronic diseases like diabetes, cardiovascular disease, and hypertension. Individuals with high DDS typically consumed more low-calorie, nutrient-dense foods, such as fruits and vegetables, which contribute to a healthy weight and reduced metabolic syndrome risk—both of which are linked to slower biological ageing.
Practical Applications
These findings offer practical guidance for individuals, healthcare providers, and policymakers on how to apply dietary diversity to promote healthier ageing in everyday life. Here’s how these insights can be implemented:
- Prioritise Variety in Daily Meals:
Incorporate a range of food groups—vegetables, fruits, whole grains, proteins, and dairy or dairy alternatives—into every meal. For example, aiming for a colourful plate by including different types of vegetables and fruits can ensure a mix of vitamins, minerals, and antioxidants. - Weekly Meal Planning with Diversity in Mind:
When planning meals for the week, include foods across multiple categories. Aim to rotate protein sources such as fish, legumes, lean meats, and tofu, along with varying grain options like quinoa, brown rice, and whole wheat. This rotation can increase nutrient intake and reduce repetitive nutrient gaps. - Promote Diverse Food Choices through Public Health Programs:
Health professionals should advocate for community initiatives that promote dietary diversity. Ideally, health agencies and community programs should support dietary diversity by incorporating it into public health initiatives. Schools, community centres, and healthcare providers should offer educational programs that emphasise the benefits of a varied diet, particularly for healthy ageing. Initiatives like cooking workshops, nutritional counselling, and community gardens can help individuals understand and incorporate diverse food choices. Public health campaigns focused on the importance of a balanced, nutrient-rich diet can also encourage healthier eating habits across all age groups. - Make Diversity Accessible for All:
Policymakers could address barriers to dietary diversity by supporting programs that increase access to fresh foods, particularly in food deserts. Subsidies for fruits, vegetables, and whole grains, as well as community gardens and farmers’ markets, could help lower-income populations afford diverse, nutrient-rich foods. - Mindful Grocery Shopping:
Encourage individuals to shop mindfully, aiming for a balance of food groups rather than focusing on one or two categories. Buying seasonal fruits and vegetables can increase diversity without inflating grocery bills, and frozen options can provide similar nutritional benefits when fresh produce isn’t available. - Use of Diverse Ingredients in Cooking:
Adding spices and herbs can enhance the flavour and nutritional profile of meals without adding extra calories. Ingredients like turmeric, ginger, garlic, and coriander/cilantro provide antioxidants and anti-inflammatory compounds that may contribute to healthy ageing. - Promote Nutrient-Dense, Anti-Inflammatory Foods:
Based on the study’s findings, focusing on foods rich in antioxidants and anti-inflammatory nutrients can be particularly effective. Encourage the inclusion of berries, leafy greens, nuts, seeds, and omega-3-rich fish like salmon, which contribute to cellular health and may counteract oxidative stress.
Critical Appraisal
Strengths of the Study
The study is notable for its large, diverse sample size from NHANES, which strengthens the generalisability of its findings. By using validated biological age metrics and thorough statistical analyses, including sensitivity testing, the study provides robust evidence that dietary diversity is linked to slower ageing. Additionally, focusing on dietary patterns rather than isolated nutrients offers a more comprehensive perspective on diet’s role in health.
Limitations and Research Gaps
- Causality Limitations: The study’s cross-sectional design limits its ability to prove causation. While a link exists between higher DDS and slower aging, further longitudinal studies are needed to confirm if dietary diversity directly influences biological ageing.
- DDS Limitations: The DDS metric does not consider portion sizes or the frequency of consumption, which may influence nutrient diversity. Future research should examine diversity in combination with quantity to refine the assessment of dietary impact on ageing.
- Residual Confounding Factors: Although the authors controlled for various factors, residual confounding may persist. For example, people with diverse diets might also engage in other healthy behaviours, such as regular exercise, that contribute to slower ageing.
- Mechanistic Pathways: While the study identifies oxidative stress as a potential mediator, the mechanisms linking dietary diversity to ageing are not fully understood. More research is needed to explore how different nutrients interact with cellular and molecular pathways to influence ageing.
- Self-Reported Dietary Data: NHANES relies on self-reported dietary recalls, which can be prone to recall bias. Integrating objective dietary tracking methods in future studies could increase the accuracy of dietary assessments.
Conclusion
Liao and Li’s study offers valuable insights into how a diverse diet may promote healthy ageing, with implications for individuals and public health strategies. By slowing biological ageing, dietary diversity could help reduce the risk of chronic diseases and improve quality of life as people age. While more research is needed to establish causality and better understand the pathways involved, these findings support the importance of a varied, nutrient-rich diet in a long-term healthy ageing strategy. Emphasising diverse food choices, accessible healthy options, and broader public health support can empower individuals to make small, sustainable changes with meaningful health impacts over time.
Reference
Liao, W., & Li, M.-Y. (2024). Dietary diversity contributes to delay biological aging. Frontiers in Medicine, 11, Article 1463569. https://doi.org/10.3389/fmed.2024.1463569
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