Effects of oat bran, rice bran, wheat fiber, and wheat germ on postprandial lipemia in healthy adults

Abstract

Six normolipidemic males ingested on separate days a low-fiber test meal [2.8 g dietary fiber (TDF)] containing 70 g fat and 756 mg cholesterol, enriched or not with 10 g TDF as oat bran, rice bran, or wheat fiber or 4.2 g TDF as wheat germ. Fasting and postmeal blood samples were obtained for 7 h and chylomicrons were isolated. Adding fibers to the test meal induced no change in serum glucose or insulin responses. The serum triglyceride response was lower (P less than or equal to 0.05) in the presence of oat bran, wheat fiber, or wheat germ and chylomicron triglycerides were reduced with wheat fiber. All fiber sources reduced chylomicron cholesterol. Cholesterolemia decreased postprandially for 6 h and was further lowered in the presence of oat bran. Serum apolipoprotein (apo) A-1 and apo B concentrations were not affected. Thus, dietary fibers from cereals may reduce postprandial lipemia in humans to a variable extent.

Methodology for studying postprandial lipid metabolism

“…As compared with a control test meal or another test meal, the studied component will be incorporated in the experimental test meal. This will make possible to evaluate the effect of the studied component on the amplitude and/or kinetics of the postprandial lipid response in subjects with normal metabolic homeostasis (Cara et al, 1992;Zampelas et al, 1994a, b;Murphy et al, 1995;Dubois et al, 1998;Roche et al, 1998a, b;Fielding et al, 2000;Harbis et al, 2001Harbis et al, , 2004van Wijk et al, 2001;Sauvant et al, 2003;Jackson et al, 2005).…”

“…The concept behind this type of approach is that a large fat load will overwhelm the normal capacity of lipoprotein handling postprandially and thus, will reveal those subjects with reduced capacity (linked to disturbed metabolism and/or diet), whereas a smaller meal may be insufficient to challenge the metabolic capacity to its limit. Cohen et al (1988) 40-120 Weintraub et al (1988) 50 g/m 2 body surface area Cohn et al (1988aCohn et al ( , 1993 1 g/kg body weight Schneeman (1990) 43 Cara et al (1992) 70 Karpe et al (1993) 50 g/m 2 body surface area Dubois et al (1994a, b) 31/42, 45 Zampelas et al (1994) 40 Frayn et al (1994) 80 Murphy et al (1995) 20-80 Fielding et al (1996) 61 Lopez-Miranda et al (1997) 1 g/kg body weight Lovegrove et al (1997) 82 Roche and Gibney, 1997;Roche et al, 1998a, b 40 Dubois et al (1998 15-50 Couillard et al (1998) 60/m 2 Shishebor et al (1999) 0.5 g/kg body weight Guerci et al (2001) 80 Harbis et al (2001) 40 Dallongeville et al (2002) 70 Harbis et al (2004) 28-29…”

“…Then, early in the 1990s, several groups of nutritionists (Redard et al, 1990;Cara et al, 1992;Williams et al, 1992;Frayn et al, 1994;Lopez-Miranda et al, 1994a;Roche and Gibney, 1995) started to select test meals with more regular amounts of energy ( about 700-1000 kcal) and fat (about 40-50 g/test meal) (see Table 1). These authors advocated that these levels are more comparable with daily meals and to the normal metabolic capacities of the subjects (gastric emptying, lipid digestion and absorption, lipoprotein handling and clearance).…”

“…Addition of some dietary fibre sources into mixed test meals (Cara et al, 1992;Lia et al, 1997) at the level of 4-10 g/meal can moderately reduce postprandial triglyceridaemia or chylomicron lipids as generated by a mixed meal ( Table 2). Sources of soluble viscous fibres (i.e., oat bran) or with hypotriglycerdemic properties (i.e., wheat germ) were shown to display such an effect in line with the interference they generate on fat lipolysis within the gut.…”

“…It is striking to observe that free cholesterol temporarily increases, whereas esterified cholesterol drops after a fatty meal (Dubois et al, 1994(Dubois et al, , 1998. As a result, total cholesterol does not show any marked change or somewhat decreases (Cara et al, 1992;Dubois et al, 1998). This means that measuring total plasma cholesterol postprandially will not add new important information.…”