EFFECTS OF DIETARY SUCROSE AND FIBERS ON BLOOD-PRESSURE IN HYPERTENSIVE RATS

In spontaneously hypertensive rats (SHR), two separate studies examine d effects on systolic blood pressure (SEP) and other cardiovascular pa rameters of different concentrations of sucrose compared to starches, soluble fibers (guar, psyllium), and insoluble fibers (cellulose, whea t bran). In the initial study, four diets were tested. The first diet was relatively high in sucrose calories (50%) and low in protein calor ies (17%) - ''high sucrose''; the second diet was relatively low in su crose (11%) and high in protein (56%) calories - ''low sucrose''. The third and fourth diets resembled the first and second diets respective ly, but cornstarch replaced sucrose - ''high and low starch''. Initial SEP in each group averaged approximately 168 mmHg. After 2 weeks of i ngesting the special diets, SEP of the high sucrose group rose rapidly and significantly, eventually rising above 200 mmHg by the terminatio n of examination. The other 3 groups maintained the original SEP until after the 3rd week when the low sucrose group developed a rapid and s ignificant SEP elevation approaching 200 mmHg. SEP of high starch and low starch remained below 181 mmHg for the two months of study. Platel ets obtained at the termination of the study from the sucrose groups c ompared to the starch groups showed increased aggregatory responses to collagen and ADP. Further, significant elevations of triglycerides an d cholesterol in the high sucrose group were found. The former paramet er was also significantly elevated in the low sucrose group. In the se cond study, adding guar and psyllium to high sucrose diets delayed sug ar-induced hypertension, while cellulose and wheat bran virtually show ed no effects. Serum insulin concentrations correlated positively with SEP, serum triglycerides, and glucose - not cholesterol. Accordingly, sucrose compared to starch ingestion in SHR can adversely influence S EP and various other cardiovascular risk factors. These effects can be delayed by the presence of soluble fibers, but not insoluble fibers, in the diets.