Ann Intern Med -- Rapid Responses for He et al., 143 (1) 1-9

Established in 1927 by the American College of Physicians

Rapid Responses to:

Articles:
Jiang He, Dongfeng Gu, Xigui Wu, Jichun Chen, Xiufang Duan, Jing Chen, and Paul K. Whelton
Effect of Soybean Protein on Blood Pressure: A Randomized, Controlled Trial
Ann Intern Med 2005; 143: 1-9 [Abstract] [Full text] [PDF]

Send comment/rapid response letter

Electronic letters published:

Letter to Editor: Balavenkatesh Kanna, Lopez Castillo MD (25 July 2005)

Letter to Editor 25 July 2005

Balavenkatesh Kanna,
MD MPH
Lincoln Medical & Mental Health Center, Affl. with Weill Medical College of Cornell University,
Lopez Castillo MD
Send rapid response to journal:
Re: Letter to Editor

bvkanna{at}aol.com Balavenkatesh Kanna, et al.

In reference to the interesting study by He et al on the efficacy of soy protein in the reduction of blood pressure (BP) for patients with pre- hypertension and stage I hypertension (1), we would like to offer the following comments.
Firstly, participants in both study groups were given potassium supplements in one of the study sites. As potassium supplementation is associated with systolic blood pressure reduction (2, 3), we are interested to know how the investigators established a lack of effect modification between soy bean protein and potassium.
Secondly, Hawksley random-zero sphygmomanometers have been found to under-record up to 1.4 mm Hg in systolic and 2.5 mm Hg in diastolic BP measurements.(4) This bias, mainly attributed to overestimation of the final zero correction during BP measurement could potentially undermine the observed results.
Further, the level of physical activity is a confounding variable that needs careful evaluation in the study groups. Physical activity can lead to significant reduction in mean systolic and diastolic blood pressures of up to 3.84 and 2.58 mm Hg respectively. (5)
References:
1. He J, Gu D, Wu X, Chen J, Duan X, Chen J, et al. Effect of soybean protein on blood pressure: a randomized, controlled trial. Ann Intern Med. 2005; 143:1-9.
2. Gu, Dongfong; He, Jiang; Wu, Xigui; Duan, Xiufang; Whelton, Paul K. Effect of potassium supplementation on blood pressure in Chinese: a randomized, placebo-controlled trial. Journal of Hypertension. 2001; 19(7):1325-1331.
3. Haddy FJ. Dietary sodium and potassium in the genesis, therapy, and prevention of hypertension. Journal of the American College of Nutrition. 1987; 6(3): 261-70.
4. McGurk C, Nugent A, McAuley D, Silke B. Sources of inaccuracy in the use of the Hawksley random-zero sphygmomanometers. Journal of Hypertension.1997;15:1379-84
5. Seamus P. Whelton; Ashley Chin, MPH, MA; Xue Xin, MD, MS; and Jiang He, MD, PhD. Effect of Aerobic Exercise on Blood Pressure: A Meta- Analysis of Randomized, Controlled Trials. 2002; 136 (7): 493-503.
Conflict of Interest:
None declared