RESUMO
ABSTRACT Epidemiological studies show that consumption of fruits and vegetables is associated with beneficial effects on human health including reduced risk of coronary artery disease (CAD). Fruits and their juices contain phytochemicals that inhibit in vitro low-density lipoprotein (LDL) oxidation and may account, in part, for their protective effect. However, reports of in vivo antioxidant effects from fruit intake are limited. We conducted a human trial to examine the in vivo effect of consumption of apples (both whole and juice) in an unblinded, randomized, crossover design. Healthy men and women added 375 ml of unsupplemented apple juice or 340 g of cored whole apple to their daily diet for 6 weeks, then crossed over to the alternate product for 6 weeks. Blood samples were obtained at baseline and after each dietary period. Compliance was monitored via biweekly 5-day food records, bodyweight checks, and meetings with study personnel. There were no significant differences between groups in intake of dietary fat, cholesterol, total carbohydrate, sugar, or calories throughout the study. Dietary fiber intake increased by 22% with whole apple consumption. Body weight, fasting serum lipid concentration, and other lipoprotein parameters were unchanged. Apple juice consumption increased ex vivo copper (Cu(++))-mediated LDL oxidation lag time by 20% compared with baseline. Apples and apple juice both reduced conjugated diene formation. Moderate apple juice consumption provides in vivo antioxidant activity. In view of the current understanding of CAD, the observed effect on LDL might be associated with reduced CAD risk and supports the inclusion of apple juice in a healthy human diet.
RESUMO
Two classes of calcium channel blockers, nisoldipine (NIS) and verapamil (VER), alter the intestinal uptake of sugars, and varying the lipid composition of the diet also modifies intestinal transport function. This study was undertaken in adult male New Zealand rabbits to assess the effect of 3 weeks of dosing with NIS (1 mg.kg-1.day-1) or VER (4 mg.kg-1.day-1) on the in vitro jejunal uptake of D-galactose and L- or D-glucose. The value of the maximal transport rate of D-galactose (Vmax) increased with NIS and VER, compared with control vehicle. The value of the apparent Michaelis constant (K(m)) rose with NIS and fell with VER, and the value of the passive permeability coefficient (Pd) estimated from the uptake of L-glucose fell with NIS and rose with VER. These effects of NIS and VER on Vmax, K(m), and Pd were prevented by feeding a high cholesterol (2.8%) supplemented chow diet (HCD), as compared with chow alone. These effects were not due to any change in the animal's weight gain or intestinal mucosal surface area. The acute exposure of the jejunal tissue in vitro to varying concentrations of NIS but not VER reduced the uptake of D-glucose but had no effect on basal short circuit current (Isc) in either chow or HCD. Isc stimulated with glucose or theophylline was less in chow-fed rabbits compared with HCD-fed rabbits given NIS or VER. Thus, the active transport of sugars by the sodium-dependent transporter in the brush-border membrane, SGLT1, and the passive uptake by the paracellular route are variably influenced by these two classes of calcium channel blockers, and this effect is modified by the cholesterol content of the diet.