In T2D and hypertension, the lower-sodium DASH4D diet reduced SBP more than a higher-sodium comparison diet at 5 wk
The reduction in systolic blood pressure (SBP) seen in this sodium-focused diet trial supports the notion of food as medicine for hypertension, but what diet to recommend to diabetes patients depends on whether blood pressure or glycemic control is the top priority, an ACP Journal Club commentary said.
A crossover trial compared four diets in patients with type 2 diabetes and elevated systolic blood pressure (SBP): the Dietary Approaches to Stop Hypertension for Diabetes (DASH4D) with lower sodium, the DASH4D diet with higher sodium, a comparison typical U.S. diet with lower sodium (CLS), and a comparison typical diet with higher sodium (CHS). All participants were provided with all of their food by the study, which found a significant reduction in SBP with the DASH4D diet compared to the CHS diet.
The study was published by JAMA Internal Medicine on June 9. The following commentary by Darren Lau, MD, PhD, and Raj Padwal, MD, MSc, was published in the ACP Journal Club section of Annals of Internal Medicine on Oct. 7.
Both DASH and low-sodium diets reduce BP, but few studies have assessed their effects in patients with T2D. Pilla and colleagues compared a diabetes-specific DASH diet and dietary sodium restriction with high- and low-sodium comparison diets in patients with T2D and hypertension. The trial achieved 96% diet adherence using a run-in period, prepared meals, and some on-site lunches or dinners. Included patients were mostly Black and were receiving a mean of 2.1 BP medications, with 79% receiving angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers. In contrast, in the original DASH trial, which found an 11.4–mm Hg SBP reduction with the treatment diet, only 21% to 25% of patients were receiving BP medications.
The 4.6–mm Hg SBP reduction seen with the DASH4DLS diet vs. CHS is similar to that of starting a new BP medication at half strength and supports the notion of food as medicine for hypertension. Most of the BP lowering was due to the low-sodium component of diet; the effect of the DASH4D component of the diet was not significant for DASH4DLS vs. CLS or DASH4DHS vs. CHS. It is possible that the macronutrient composition of DASH4D was similar to the comparison diet. Alternatively, the incremental benefit of DASH4D may be smaller in patients who are already receiving multiple BP drugs. Regardless, the results support sodium reduction as the key dietary intervention to reduce BP in adults with T2D.
As a feeding trial, the DASH4D trial shows efficacy, but it may not offer a practical reflection of real-world effectiveness, especially over longer time frames. Patients with T2D may have other diet-related goals, such as weight loss or glycemic control. The effects of DASH4D and low-sodium diets on glucose levels are unclear, pending the results of the DASH4D-CGM substudy (NCT04286555). Whether to recommend the DASH4DLS diet or sodium restriction alone, therefore, depends on the patient. These diets may be best suited to patients with reasonably well-controlled glucose levels for whom BP control is a priority.