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.