CATEGORY: EATING FOR HEART HEALTH
Adults with type 2 diabetes had systolic blood pressure 4.6 mm Hg lower when they ate a heart-friendly diet with less salt than when the same people ate a typical American diet with more salt, in a randomized trial that cooked and supplied every meal.1 Diastolic pressure, the lower of the two numbers, fell by 2.3 mm Hg. The people in the trial started at an average of 135/75, and two thirds of them were already taking two or more blood pressure medications, so the food was competing with treatment that had largely done its work.
Every Meal Came From the Study Kitchen
This was not a study that asked people what they ate and waited to see what happened. All 102 participants were given every meal, and each of them rotated through four different diets in an order decided by chance: a DASH diet adapted for diabetes, or a typical American diet, each served at a higher and a lower sodium level. Each diet lasted five weeks, and 85 people completed all four. Because everyone ate all four diets, each person served as their own comparison, which strips out the differences between individuals that make eating studies so hard to read.
One design detail carries more weight than it looks. Calories were adjusted week by week so that nobody lost weight. That means the movement on the cuff came from what was in the food rather than from a smaller waistline, which is the usual confusion in any study where diet and weight change together.
The Group Earlier DASH Trials Had Largely Passed Over
The DASH eating pattern has been studied since the 1990s, but the trials that built its reputation were not focused on people with type 2 diabetes, and they enrolled people who were mostly not yet on medication. That left an open question the researchers set out to answer: does a change in diet still buy anything for someone whose blood pressure is already being managed with drugs, and whose diabetes changes how the body handles salt and fluid? The answer in this trial was that it did, in a group where the easy gains had already been taken.
The participants were not a cross-section of the country. Their average age was 66, two thirds were women, and 87% described themselves as Black, a group that carries more high blood pressure and more of its consequences than the population as a whole.
Most of the Change Arrived Within Three Weeks
The blood pressure difference did not build slowly over the five weeks. Most of it was in place by the third week and then held steady, which tells a reader something about how this kind of change behaves: it is a response to what is on the plate this week, not a reward that accumulates over months.
The trial also reported which half of the change was doing more work. Lowering the sodium appeared to matter more than switching the dietary pattern itself, though the largest difference came from doing both at once, which is the comparison the 4.6 mm Hg figure describes.
A Number on a Cuff Is Not the Same as a Heart Attack
This trial measured blood pressure over five weeks. It did not measure heart attacks, strokes or deaths, and it was not built to. The bridge between the two comes from other research, and the closest relative is the DASH-Sodium trial, which ran the same kind of controlled feeding design in 412 adults without diabetes more than two decades ago and found the same thing in the same direction: the DASH pattern lowered blood pressure, cutting sodium lowered it further, and the two together lowered it most.2 Two feeding trials, a generation apart, in different populations, landing the same way is a stronger statement than either one alone.
What neither trial settles is how far down the sodium scale the benefit keeps going, which is the part of the salt question that researchers still argue about. And 102 people eating provided meals for five weeks is a long way from everyday life, where nobody hands you your dinner.
Key Takeaways
- In a randomized feeding trial, adults with type 2 diabetes had systolic blood pressure 4.6 mm Hg lower on a DASH-style diet with less sodium than on a typical American diet with more sodium.
- The effect appeared in people who were already taking blood pressure medication, and it did not depend on losing weight, because calories were held steady.
- Most of the difference was present within three weeks, and the trial reported that the sodium reduction contributed more than the change in dietary pattern.
- The trial measured blood pressure, not heart attacks or strokes, and it ran for five weeks per diet in 102 people who were given all their meals.
References
- Pilla SJ, Yeh HC, Mitchell CM, et al. Dietary Patterns, Sodium Reduction, and Blood Pressure in Type 2 Diabetes: The DASH4D Randomized Clinical Trial. JAMA Intern Med. 2025;185(8):937–937. link
- Sacks FM, Svetkey LP, Vollmer WM, et al. Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet. N Engl J Med. 2001;344(1):3–10. link