The Effects of Dietary Patterns on Urinary Albumin Excretion: Results of the Dietary Approaches to Stop Hypertension (DASH) Trial

Background

Dietary studies designed to decrease the urinary albumin excretion rate (AER) typically reduce protein by increasing lower protein plant foods and decreasing higher protein animal products.

Study Design

We evaluated AER while increasing protein intake in the Dietary Approaches to Stop Hypertension (DASH) Trial (randomized, parallel group, 8 week controlled feeding).

Setting & Participants

378 individuals without diabetes with prehypertension or stage I hypertension.

Intervention

The DASH diet, 18% energy from protein, emphasizes, among other features, low-fat dairy products; and the fruit/vegetable (FV) and control diets, each with 15% energy from protein.

Outcome

AER.

Measurements

We measured AER by using immunoassay and covariates at baseline and after 8 weeks.

Results

Baseline AER had a geometric mean value of 4.0 ± 0.2 (SE) mg/24 h. In 285 participants with baseline AER less than 7 mg/24 h, AER was unchanged by diet treatment (geometric mean, 2.5 ± 0.2 mg/24 h in the control diet, 3.0 ± 0.2 mg/24 h in the FV diet, and 2.8 ± 0.2 mg/24 h in the DASH diet). Conversely, in 93 participants with baseline AER of 7 mg/24 h or greater, end-of-feeding AER was lower in the FV diet (6.6 ± 1.0 mg/24 h) than in the control (11.4 ± 1.8 mg/24 h; P = 0.01) or DASH diets (11.7 ± 1.6 mg/24 h; P = 0.005). The DASH and control diets were not different (P = 0.9).

Limitations

Long-term AER change not studied.

Conclusions

The decrease in AER after 8 weeks occurred in only those with high-normal baseline AER in the FV diet, in a pattern distinct from the blood pressure decrease. The DASH diet did not increase AER despite a 3% increase in energy from protein.

Index Words: Albumin excretion, short term feeding, protein, phytochemical