European Journal of Nutrition (v.47, #4)

Bioactive peptides and proteins from foods: indication for health effects by Niels Peter Möller; Katharina Elisabeth Scholz-Ahrens; Nils Roos; Jürgen Schrezenmeir (171-182).
Some dietary proteins cause specific effects going beyond nutrient supply. A number of proteins seem to act directly in the intestine, such as IGFs, lactoferrin and immunoglobulins. Many substances, however, are peptides encrypted in intact molecules and are released from their encrypted position by enzymes during gastrointestinal transit or by fermentation or ripening during food processing. Among food-derived bioactive proteins and peptides from plants and animals, those obtained from milk are known in particular. Numerous effects have been described after in vitro and animal trials for bioactive proteins and peptides, such as immunomodulating, antihypertensive, osteoprotective, antilipemic, opiate, antioxidative and antimicrobial. This article reviews the current knowledge of the existence of bioactive proteins and of in vitro bioactivity and the present evidence of health effects exerted by such substances or products containing bioactive compounds. For example, there is evidence for the antihypertensive effects of milk products fermented with Lactobacillus helveticus containing the tripeptides IPP and VPP, which inhibit angiotensin converting enzyme, and for osteoprotective effects by milk basic protein. There is less profound evidence on the immunomodulating effects of lactoferrin and postprandial triglyceride reduction by a hydrolysate of bovine hemoglobin.
Keywords: bioactive proteins; bioactive peptides; food proteins; immunomodulation; antihypertensive activity; osteoprotection; antilipemic activity

Polyunsaturated fatty acids support epithelial barrier integrity and reduce IL-4 mediated permeability in vitro by Linette E. M. Willemsen PhD; Marleen A. Koetsier; Martin Balvers; Christopher Beermann; Bernd Stahl; Eric A. F. van Tol (183-191).
The intestinal mucosa functions as a barrier against harmful dietary and microbial antigens. An intact gut barrier forms a prerequisite for protection against infection and allergy. Both allergic and inflammatory mediators (e.g. IL-4, IFN-γ) are known to compromise the epithelial barrier integrity by enhancing permeability. Breast milk provides protection against infection and allergy and contains polyunsaturated fatty acids (PUFA).Although PUFA are commonly used in infant formulas their effect on intestinal barrier is still poorly understood. Therefore the effects of distinct PUFA (n-6: LA, GLA, DGLA, AA; n-3: ALA, EPA, DHA) and a fat blend with PUFA composition similar to that of the human breast milk fat fraction, on barrier integrity were investigated.Human intestinal epithelial cells (T84) were pre-incubated with individual PUFA or a lipase treated fat blend, with or without subsequent IL-4 exposure. Barrier integrity was evaluated by measuring transepithelial resistance and permeability. Membrane phospholipid composition was determined by capillary gas chromatography.DGLA, AA, EPA, DHA and to a lesser extend GLA enhanced basal TER and strongly reduced IL-4 mediated permeability, while LA and ALA were ineffective. Furthermore, the lipase treated fat blend effectively supported barrier function. PUFA were incorporated in the membrane phospholipid fraction of T84 cells.Long chain PUFA DGLA, AA, EPA and DHA were particularly effective in supporting barrier integrity by improving resistance and reducing IL-4 mediated permeability. Fat blends that release specific PUFA upon digestion in the gastrointestinal tract may support natural resistance.
Keywords: permeability; IL-4; polyunsaturated fatty acids; arachidonic acid (AA); docosahexaenoic acid (DHA)

Comparison of enzymatically synthesized inulin, resistant maltodextrin and clofibrate effects on biomarkers of metabolic disease in rats fed a high-fat and high-sucrose (cafeteria) diet by Junko Sugatani; Makoto Osabe; Tadashi Wada; Kasumi Yamakawa; Yasuhiro Yamazaki; Tadanobu Takahashi; Akira Ikari; Masao Miwa PhD (192-200).
While naturally occurring inulin has anti-hyperlipidemic effects in animals and humans, health effects of synthetic inulin with different degrees of fructose polymerization remain poorly understood.Our study aimed at distinguishing health effects of synthetic inulin with different degrees of fructose polymerization (DP) from those of resistant maltodextrin and clofibrate.We examined effects of synthetic inulin on serum and liver lipid profiles and blood biochemical parameters in rats fed a high-fat and high-sucrose (HF, cafeteria) diet when compared to resistant maltodextrin and clofibrate.Treatment with inulin (average DP = 6–8, 16–17 and 23) and resistant maltodextrin for 3 weeks reduced the elevation in liver levels of triacylglycerol and total cholesterol of rats fed the cafeteria diet but not the standard diet. In these groups, inulin (average DP = 16–17) significantly reduced the portal plasma glucose level. Moreover, the levels of portal plasma propionate and circulating serum adiponectin, which were decreased in cafeteria rats, recovered to nearly normal levels after administration of inulin (average DP  = 16–17). In addition, the dietary inulin suppressed elevation in levels of portal plasma insulin and circulating serum leptin and induction of acetyl-CoA carboxylase and fatty acid synthase mRNAs in the liver of cafeteria rats, consistent with the reduction of liver lipids. The dietary inulin and clofibrate markedly reduced triacylglycerol levels in serum very low density lipoprotein (VLDL) and liver and epididymal adipose tissue weights of cafeteria rats; the extent of suppression by the dietary inulin was higher than that by clofibrate. No additive or synergistic effect of the dietary inulin and clofibrate was found in decrease in circulating serum VLDL and liver lipid levels.These observations indicate that the dietary inulin may prevent the development of metabolic disease such as hyperlipidemia and hyperinsulinemia caused by intake of cafeteria diet, in association with suppression of liver lipogenesis.
Keywords: synthetic inulin; anti-metabolic disease; clofibrate; propionate; glucose

Changes in predictors and status of homocysteine in young male adults after a dietary intervention with vegetables, fruits and bread by Tonje Holte Stea; Mohammad Azam Mansoor; Margareta Wandel; Solveig Uglem; Wenche Frølich (201-209).
Elevated plasma total homocysteine (p-tHcy) is associated with increased risk of cardiovascular disease, and an inverse association has been shown between the dietary intake of B-vitamins, B-vitamin profile and the concentration of p-tHcy.The main objective of this investigation was to study the effect of a dietary intervention focusing on an increased intake of vegetables, fruits and bread. The effect of the dietary intervention was determined by the changes in plasma concentrations of tHcy, cysteine (cys), riboflavin, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) and serum concentrations of folate and vitamin B12.An intervention study with duration of 5 months, including 541 male recruits from the Norwegian National Guard, Vaernes and a control group, including 209 male recruits from the Norwegian Army, Heggelia.The dietary intervention resulted in decreased concentration of p-tHcy (−10%, P = 0.002), p-cys (−6%, P < 0.001) and FMN (−11%, P = 0.310) and increased concentration of riboflavin (+23%, P < 0.001) and FAD (+10%, P = 0.008) in the intervention group compared with the control group. The change in p-tHcy concentration was positively related to the change in the concentration of p-cys (P < 0.001) and FMN (P = 0.035) and inversely related to the change in concentration of folate (P = 0.021).A dietary intervention program focusing on an increased intake of vegetables, fruits and bread showed a favourable effect on the concentration of p-tHcy and its metabolites. Our findings suggest that the changes in the concentration of p-cys, folate and FMN seem to be predictors of changes in the p-tHcy concentration.
Keywords: dietary intervention; homocysteine; B-vitamins; young men

Dietary magnesium intake is related to metabolic syndrome in older Americans by Nicola M. McKeown PhD; Paul F. Jacques ScD; Xinli L. Zhang; Wenyen Juan; Nadine R. Sahyoun PhD (210-216).
Magnesium (Mg) is an essential cofactor for enzymes involved in glucose and insulin metabolism. Low intakes of dietary magnesium may be linked to greater risk of metabolic syndrome (MS) in older adults.The objective of this study was to examine the cross-sectional relationship between dietary Mg intake, metabolic risk factors and MS in elderly adults.This study was conducted in a sample of 535 (179 men and 356 women) community-living adults aged 60 years and in Boston Massachusetts between the years 1981 and 1984. Dietary Mg intake was assessed by a 3-day food record and categorized by quartiles of dietary intake. The MS was defined based on criteria set by the Third Report of the National Cholesterol Education Program except that body mass index was used in place of waist circumference. Logistic regression analysis was used to examine the association between quartile categories of Mg intake, prevalence of MS and components of the MS. Models were adjusted for age, gender, BMI, race, educational attainment, marital status, smoking status, alcohol intake, exercise, energy intake, percentage of calories from saturated fat, use of antihypertensive or lipid medication.Mg intake was inversely associated with the MS; those with the highest intake of Mg had significantly lower risk of having MS compared to the lowest quartile of intake (OR: 0.36, 95% CI 0.19–0.69, P for trend 0.002). Significant inverse relationships were observed between Mg intake and BMI (OR: 0.47, 95% CI: 0.22–1.00, P trend = 0.03), and fasting glucose (OR: 0.41, 95% CI 0.22–0.77, P trend = 0.005).Our study demonstrates that Mg intake is inversely associated with prevalence of the MS in older adults. Older adults should be encouraged to eat foods rich in Mg, such as green vegetables, legumes and whole-grains.
Keywords: dietary magnesium; metabolic syndrome; older adults

Does the biomarker 15N-lactose ureide allow to estimate the site of fermentation of resistant starch? by Lieselotte Cloetens; Vicky De Preter; Henriette De Loor; Paul Rutgeerts; Kristin Verbeke PhD (217-223).
We evaluated the effect of resistant starch (RS) and resistant starch with wheat bran (RS+WB) on the colonic ammonia metabolism in healthy volunteers using the biomarker 15N-lactose ureide (15N-LU). Particularly, it was investigated whether this biomarker allowed to estimate differences in the site of fermentation. Ten volunteers were included in a placebo-controlled crossover study. They consumed in random order 2 × 15 g RS/day for 2 weeks and placebo for 2 weeks separated by 2 weeks wash-out. At baseline, on the first day of each intake period and after each intake period, they consumed a 15N-labelled test meal and collected all urine in different fractions for 48 h. In ten other volunteers, the effect of 2 × 15 g RS/day and of 2 × 15 g RS  + 2 × 6 g WB was compared. These volunteers collected urine and feces for 72 h. 15N-content of urine and feces was measured using combustion-isotope ratio mass spectrometry. RS exerted a significant decrease in cumulative urinary 15N-excretion which was different from placebo. The effect was most pronounced in the 6–24 h urine fraction which suggest fermentation in the proximal colon. The effect of RS+WB on cumulative urinary 15N-excretion was not significantly different from the effect of RS. A less pronounced decrease in the 6–24 h fraction was observed suggesting less fermentation in the proximal colon whereas no indications for more distal fermentation were observed. Since about 80% of the cumulative urinary 15N was recovered within 24 h, it was concluded that the biomarker 15N-LU was useful to monitor processes in the proximal colon rather than in the distal colon.
Keywords: stable isotope; prebiotic; wheat bran; resistant starch; site of fermentation