Balancing cost, affordability and environmental impacts of the DASH diet in older adults

Clarissa L Leydon^1,2*Sinéad N McCarthy²Janas M Harrington¹

• ¹School of Public Health, College of Medicine and Health, University College Cork, Cork, Ireland, Cork, Ireland
• ²Department of Agrifood Business and Spatial Analysis, Teagasc Food Research Centre, Ashtown., Dublin, Ireland

Introduction The Dietary Approaches to Stop Hypertension (DASH) diet is associated with reduced chronic disease risk and potential environmental benefits. However, financial cost may limit adoption among older adults, for whom the DASH diet is commonly recommended. As cardiovascular disease remains a leading cause of morbidity and mortality in Ireland, this study evaluated the financial cost of adhering to the DASH diet and examined how dietary cost relates to environmental impacts and affordability among older adults in the context of state pension income. Methods Men and women aged 52-77 years (n=1352) were included in the study. Dietary intake was assessed using a validated food frequency questionnaire, and DASH adherence scores were calculated. Monetary costs were obtained by collecting online prices from a supermarket. Environmental impacts, including greenhouse gas emissions (GHGE) and blue water use (BWU), were calculated using secondary life cycle assessment data from the United Kingdom. Participants were divided into quartiles of DASH adherence, and dietary costs, environmental impacts, and cost intensities per euro spent were compared across quartiles. Results Dietary cost increased with DASH adherence, with high adherence costing €9.88 per day compared with €8.14 per day in low adherence participants. Total daily GHGE did not differ significantly across adherence quartiles, although cost intensity for GHGE improved with higher adherence (Q1: 0.84 kg CO₂-eq/€, Q4: 0.69 kg CO₂-eq/€). In contrast, total daily BWU rose substantially from 344 L in Q1 to 537 L in Q4, with BWU cost intensity also higher among those with high adherence (52.98 vs. 43.16 L/€). When evaluated relative to state pensions, a low adherence DASH diet represented 19-21% of weekly income, compared with 23-25% for high adherence across both contributory and non-contributory pension schemes. Discussion Greater DASH adherence improved dietary carbon efficiency but increased water use, driven largely by non-DASH items, as well as overall daily cost. These factors may limit adoption among older adults, underscoring the need for policy measures that reduce the cost of DASH-aligned foods and support equitable access to healthy and environmentally favourable diets.