Soy protein = less dysfunction in renal transplant patients

[pelagia]

http://ndt.oxfordjournals.org/cgi/content/abstract/22/1/229

SOY PROTEIN DIET IMPROVES ENDOTHELIAL DYSFUNCTION IN RENAL TRANSPLANT PATIENTS

Adamasco Cupisti1, Lorenzo Ghiadoni1, Claudia D'Alessandro1, Isabella Kardasz1, Ester Morelli1, Vincenzo Panichi1, Daniela Locati2, Sheila Morandi2, Alessandro Saba3, Giuliano Barsotti1, Stefano Taddei1, Anna Arnoldi2 and Antonio Salvetti1
1Department of Internal Medicine, University of Pisa, 2Department of Agri-Food Molecular Science, University of Milan and 3Institute of Chemistry of Organometallic Compounds, National Research Council, Pisa, Italy

ABSTRACT
Background. Since it has been demonstrated that soy diet can improve endothelial function, in the present study we evaluated the effect of dietary substitution of 25 g of animal proteins with soy proteins on endothelial dysfunction in renal transplant patients.

Methods. In 20 renal transplant patients (55 ± 11 years, serum creatinine 1.7 ± 0.6 mg/dl), brachial artery flow mediated dilation (FMD) and endothelium-independent vasodilation (sublingual nitroglycerine, 25 µg) were measured at baseline, after 5 weeks of a soy diet and finally after 5 weeks of soy wash-out. Changes in plasma lipids, markers of oxidative stress (lipid peroxides, LOOH) and inflammation (C-reactive protein), isoflavones (genistein and daidzein), asymmetric dimethyl arginine (ADMA) and L-arginine were also evaluated.

Results. At baseline, patients showed a significantly lower FMD as compared with age-matched healthy subjects (3.2 ± 1.8 vs 6.3 ± 1.9, respectively; P < 0.001), while response to nitroglycerine was similar. After soy diet, actual protein intake was not changed, cholesterol and lipid peroxides were significantly reduced, and isoflavones were detectable in plasma. Soy diet was associated with a significant improvement in FMD (4.4 ± 2.0; P = 0.003 vs baseline), while response to nitroglycerine was unchanged. Improvement in FMD was related to L-arginine/ADMA ratio changes, but no significant relation was found to changes in cholesterol, lipid peroxides or genistein and daidzein plasma concentrations. After 5 weeks of soy diet discontinuation, FMD (3.3 ± 1.7%) returned to baseline values and isoflavones were no longer detectable in plasma.

Conclusions. A soy protein diet for 5 weeks improves endothelial function in renal transplant patients. This effect seems to be strictly dependent on soy intake as it disappears after soy withdrawal and is mediated by an increase in the L-arginine/ADMA ratio, independently of change in lipid profile, oxidative stress or isoflavones.
Keywords: ADMA; chronic kidney disease; diet; endothelial dysfunction; L-arginine; renal transplant; soy

[Zach]

Very interesting.
There's so much nephrologists need to learn about nutrition and kidney health.

[pelagia]

Just a little more on L-arginine, from wikipedia

L-arginine is a precursor for nitrous oxide.  Nitrous oxide relaxes blood vessels.  Arginine is used in many conditions where vasodilation is required. The presence of asymmetric dimethylarginine (ADMA), a close relative, inhibits the nitric oxide reaction; therefore, ADMA is considered a marker for vascular disease, just as L-arginine is considered a sign of a healthy endothelium.

Here is what is given in wiki as benefits of L-arginine:

Precursor for the synthesis of nitric oxide (NO)
Stimulation of the release of growth hormone.
Improves immune function
Reduces healing time of injuries (particularly bone)
Quickens repair time of damaged tissue
Reduces risk of heart disease
Increases muscle mass
Reduces adipose tissue body fat
Helps improve insulin sensitivity
Helps decrease blood pressure
Alleviates male infertility, improving sperm production and motility
Increases circulation throughout the body, including the sex organs

You can buy supplements, but a food source is probably a much better way to get this compound into the diet. 

Should we start a thread for transplant recipients called "How to get more soy into your diet?" !

[Sunny]

I have found my body is able to synthesize protein products better when the protein is not animal meat. Makes sense soy protein would provide the same kinds of outcomes.

[monrein]

A "More Soy in your Diet" thread sounds like a good idea to me.  I love the steamed Edamame pea pods and would welcome any other suggestions.  I hereby resolve to eat more soy protein.

[Wallyz]

{sigh}  I hate soy. I hate the taste of soy.  SOy sauce is OK, but I can't eat that now.

Tofu.  Tempeh.  Yee- hah.

[pelagia]

My brother-in-law has worked as a gourmet personal chef, with a leaning towards vegetarian and vegan.  I sent him a note requesting some recipes as mine are all pretty ho hum.  One of my favorite tofu-based dishes is Vietnamese.  Basically it is crispy fried tofu served in wedges over a big salad, with a very light dressing on the side and garnished with chopped peanuts.  Of course, the secrets are in how they get the tofu to be crispy and how they make the dressing.  I have had many great tofu dishes in Asian restaurants.