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Research: PREUSS and colleagues,
Listed in Issue 34
Abstract
PREUSS and colleagues, Department of Medicine, Georgetown University Medical Center, Washington DC 20007 USA studied, in spontaneously hypertensive rats (SHR), the effects upon systolic blood pressure (SBP) of ingesting 3 modulators of insulin metabolism: chromium polynicotinate, bis(maltolato)oxovanadium (BMOV) and the herb Gymnema sylvestre .
Background
Methodology
In one study, SHR were fed either a starch, sugar or sugar diet containing chromium polynicotinate, bis(maltolato)oxovanadium (BMOV) or Gymnema sylvestre. Tail SBP was estimated indirectly, blood chemistries measured, and thiobarbituric acid reacting substances (TBARS) formation, a measure of lipid peroxidation, determined in liver and kidney tissue. In a second study, SBP was measured in SHR fed diets with differing concentrations of BMOV.
Results
Compared with starch, SHR fed sucrose demonstrated, within days, a significant elevation of SBP which was maintained throughout the study. The addition of chromium polynicotinate to the sucrose diet at the start of the study prevented sucrose-induced elevation of SBP for 2 weeks; thereafter SBP rose significantly. High concentrations of BMOV overcame the sucrose-induced SBP rise and also lowered SBP below levels observed in SHR fed the starch diet; however, there was a marked weight loss. In the second study which looked at effects of differing concentrations of BMOV, even at the 0.01% w/w concentration of BMOV, SBP was still significantly decreased, and SHR did not lose body weight (BW) early on. G sylvestre either did not change or in fact elevated SBP; however, G sylvestre decreased circulating cholesterol concentrations. Chromium polynicotinate and BMOV decreased TBARS formation and chromium polynicotinate decreased renal TBARS.
Conclusion
Chromium decreased the portion of SBP elevated by high sucrose intake; however, high levels of sucrose ingestion can eventually counteract this. BMOV overcame sucrose-induced SBP elevation and some genetic hypertension, and unlike chromium, this decrease was not counteracted by high levels of dietary sucrose. Although G sylvestre significantly lowered cholesterol, indicating an effect upon metabolism, G sylvestre did not lower and even raised SBP.
References
Preuss HG et al. Comparative effects of chromium, vanadium and gymnema sylvestre on sugar-induced blood pressure elevations in SHR. J Am Coll Nutr 17(2): 116-23 Apr 1998.