European Journal of Nutrition (v.41, #1)
Nutritional and metabolic consequences of the early Maillard reaction of heat treated milk in the pig by Alain Rérat; Régine Calmes; Pierre Vaissade; Paul-André Finot (1-11).
Background During the processing of foods, the Maillard reaction may occur contributing to altering the nutritional value of proteins. In dairy products the formation of lactuloselysine reduces the availability of lysine but the effects on the other nutrients are not very well known. Aim of the study Determination of the consequences of a high level of lactulose-lysine in milk on the bioavailability of skim milk nutrients and the kinetics of their appearance in the portal blood and of their urinary and faecal excretions and extrapolation to lower heat treatments and to man, using the pig model. Methods Sub-adult pigs were fitted, under anaesthesia, with permanent catheters in the portal vein, carotid artery and urethra, and with an electromagnetic flow probe around the portal vein. Each animal was successively fed with two experimental meals containing an equal amount of dried skim milk (SM), either lyophilised or heat treated to obtain an intense Maillard reaction, (M-SM) resulting in a 50 % lysine blockage. Portal and arterial concentrations and flux of individual amino acids (AA), glucose, galactose and fructoselysine were measured for a period of 12h after the meals. Lysine, fructoselysine and AA excreted in the urine and faeces within 72h were also determined. Results In M-SM containing 50 % blocked lysine, no other AA was chemically modified. Fructoselysine appeared in the portal blood very late compared to amino acids resulting from a very slow release and corresponded to 8.2 and 18.6 % of the ingested amount after 12 and 72h, respectively. Significant changes of the appearance in the portal blood were observed only for lysine (−60 %), alanine (−17 %) and cystine (+37 %). A small decrease in the digestibility of most AA during the same period was observed, which was significant after 48h for lysine, phenylalanine, cystine, aspartic acid, glycine and total AA (−6 %). Conclusion It was confirmed that lactuloselysine was not bioavailable. The loss in protein nutritive value was mainly due and proportional to the deterioration of lysine and, to a lesser extent, to the decrease in the digestibility of some essential AA. Taking into account the very high level of lactuloselysine in the M-SM sample studied, it may be concluded that in common foods such as milk, infant formulas, biscuits, bread, pasta, containing lower levels of blocked lysine, the nutritional loss is primarily due to the loss of lysine and to a less extent to the decrease in the digestibility of other essential AA.
Keywords: Key words Maillard reaction – lactuloselysine – absorption – excretion – pig
Effects of long-term supplementation with whey proteins on plasma glutathione levels of HIV-infected patients by P. Micke; K. M. Beeh; R. Buhl (12-18).
Background HIV infection is characterized by an enhanced oxidant burden and a systemic deficiency of the tripeptide glutathione (GSH), a major antioxidant. The semi-essential amino acid cysteine is the main source of the free sulfhydryl group of GSH and limits its synthesis. Whey proteins are rich in cysteine as well as in GSH precursor peptides. Aim of the study In order to evaluate the effects of whey supplementation on plasma GSH levels, HIV-infected patients were treated with whey proteins for a period of six months. Methods In a double blind clinical trial, 30 patients were randomized to a daily dose of 45 g whey proteins of either Protectamin® (Fresenius Kabi, Germany) or Immunocal® (Immunotec, Europe) for 2 weeks. Eighteen patients (16 male, 42 ± 9.4 yr, 249 ± 99 CD4+ lymphocytes/l) continued the trial with a daily dose of 45 g of Protectamin for six months. Results Pre-therapy, total plasma GSH levels (Protectamin: 1.92 ± 0.6 μM; Immunocal: 1.99 ± 0.9 μM) were less than normal (2.64 ± 0.7 μM, p = 0.03). After two weeks of whey protein supplementation, plasma total GSH levels increased in the Protectamin group by 44 ± 56 % (2.79 ± 1.1 μM, p = 0.004), while the difference in the Immunocal group did not reach significance (+24.5 ± 59 %, 2.51 ± 1.48 μM, p = 0.43). Consequently, all patients continuing the trial were openly switched to Protectamin. After six months, total GSH plasma levels were still significantly elevated compared to baseline (day 1: 1.95 ± 0.8 μM vs. month 1: 2.18 ± 0.8 μM, p = 0.19; month 3: 2.39 ± 0.9 μM, p = 0.056; month 6: 2.47 ± 0.8 μM, p = 0.033). Body weight, T-cell counts, and other clinical parameters did not change. The most common mild side effect was intestinal disturbance; severe adverse events did not occur. Conclusion Supplementation with whey proteins persistently increased plasma glutathione levels in patients with advanced HIV-infection. The treatment was well tolerated. A larger long-term trial is clearly warranted to evaluate whether this positive influence on the glutathione metabolism translates into a more favorable course of the disease.
Keywords: Key words HIV – glutathione – cysteine – whey protein – oxidants – antioxidants
The hypocholesterolemic effect of lemon peels, lemon pectin, and the waste stream material of lemon peels in hybrid F1B hamsters by A. H. M. Terpstra; J. A. Lapré; H. T. de Vries; A. C. Beynen (19-26).
Background We found in preliminary studies with hamsters that citrus peels have a cholesterol lowering effect comparable to that of pectin extracted from these peels. Aim of the study We wanted to examine whether the cholesterol lowering effect of the peels could be completely accounted for by the pectin in the peels. Methods We fed cholesterol enriched (0.1 %,w/w) semipurified diets containing 3 % (w/w) of cellulose, lemon peels, lemon pectin, and the waste stream material of the lemon peels to hybrid F1B hamsters for a period of 8 weeks. The waste stream of the lemon peels is the left over after extraction of the lemon pectin. Results Feeding the semipurified diets resulted in an increase of plasma cholesterol levels in all the dietary groups after 2 and 4 weeks on the diets. Cholesterol concentrations in the cellulose fed hamsters continued to increase after 4 weeks on the diet, whereas cholesterol levels in the other groups had reached a plateau. As a consequence, the plasma cholesterol levels in the hamsters fed the peels (5.59 ± 0.74 mmol/L, mean ± SD, n = 14), pectin (5.19 ± 0.48 mmol/L), or waste stream (5.53 ± 0.94 mmol/L) were lower than those in the hamsters fed cellulose (6.71 ± 1.52 mmol/L) after 8 weeks on the diets. Differences in total plasma cholesterol were reflected in differences in both VLDL and LDL cholesterol concentration, but this effect was more distinct for the VLDL. There was no effect of the type of fiber on HDL cholesterol levels. Liver cholesterol concentrations paralleled the concentrations of plasma cholesterol and the liver cholesterol concentrations in the hamsters fed the peels (3.57 ± 1.01 μmol/g liver, mean ± SD, n = 14), pectin (4.86 ± 1.42), and the waste stream (4.96 ± 1.89) were lower than those in the cellulose group (7.19 ± 2.32). The hamsters fed the peels, pectin, or waste stream tended to have a higher excretion of fecal bile acids and neutral sterols then the cellulose fed hamsters. Conclusion The results of this study suggest that lemon peels and the waste stream of the lemon peels are as effective in lowering plasma and liver cholesterol in hamsters as the pectin extracted from the peels and that also compounds other than pectin are probably responsible for the cholesterol lowering effect of the citrus peels.
Keywords: Key words Hamsters – Pectin – Lipoproteins – Cholesterol
Vitamin C and vitamin E antagonistically modulate human vascular endothelial and smooth muscle cell DNA synthesis and proliferation by Gudrun Ulrich-Merzenich; Christine Metzner; Beate Schiermeyer; Hans Vetter (27-34).
Background Vitamin C and E are suggested to play a preventive role in the pathogenesis of atherosclerosis. They reduce oxidation of low density lipoproteins (oxLDL), thereby protecting human vascular arterial endothelial and smooth muscle cells from oxLDL induced damages. Aims of the Study Since vascular arterial endothelial and smooth muscle cells are both involved in atherosclerotic plaque formation, we simultaneously examined the effect of vitamin C, E and oxLDL on their DNA synthesis and proliferation to further elucidate their joint role in this process. Methods Human umbilical arterial endothelial cells (HUAEC) and human arterial smooth muscle cells (HUASMC) were incubated with “preventive concentrations” of vitamin C (60μM) and E (30μM) and with LDL (60μg/ml) of increasing oxidation grade. Cell proliferation and DNA synthesis were determined by cell count and [3H]-thymidine uptake, respectively. Results Vitamin C alone or in combination with E increased significantly cell number and [3H]-thymidine uptake in HUAEC. The combination exhibited the strongest effect. In contrast, cell number and [3H]-thymidine uptake in HUASMC were significantly decreased in the presence of vitamin C, vitamin E or its combination. OxLDL (60 μg/ml) inhibited cell number and [3H]-thymidine uptake in HUAECs, the latter in an oxidation-grade dependent manner. In HUASMC oxLDL promoted a higher cell number and [3H]-thymidine uptake. If induced by minimally oxLDL, this reduc-tion or increase could be partially reversed by vitamin C alone or in combination with vitamin E. Conclusion Vitamin C and E, alone or in combination, modulate proliferation and DNA synthesis of human arterial endothelial and muscle cells and this modulation is antagonistic. Thus, vitamin C and E may act “preventive” on atherosclerotic plaque formation in two steps: first reendothelialisation is promoted, then HUASMC growth is inhibited.
Keywords: Key words Reendothelialisation – smooth muscle cells – lipoproteins – vitamin E and C
Alcohol, cigarette smoking, dietary factors and the risk of colorectal adenomas and hyperplastic polyps – a case control study by Juergen Georg Erhardt; Heinz Peter Kreichgauer; Christoph Meisner; Johann Christian Bode; Christiane Bode (35-43).
Background & aims Epidemiological studies on the association between lifestyle factors and the risk of colorectal polyps have led to conflicting results. The aim of the present study was to assess the relationship between alcohol consumption, dietary risk factors, cigarette smoking and colorectal adenomas or hyperplastic polyps, respectively. Methods Information on alcohol consumption, a detailed dietary history, cigarette smoking and intake of non-steroidal anti-inflammatory drugs was collected among 502 Caucasian subjects undergoing complete colonoscopy, 207 with colorectal adenomas, 71 with hyperplastic polyps and 224 controls with no polyps. Results Using univariate analysis significant risk factors for adenomas were age above 55 years, male sex, BMI > 24 (OR 1.91 [1.26–2.88]), an intake of ham + sausage > 15 g/day (OR 1.87 [1.12–3.11]) and smoking (OR 1.71 [1.17–2.5]). The association with alcohol intake > 7 g/day was not significant (OR 1.42 [0.97–2.07], p = 0.071). In the multiple logistic regression only age > 55 years (OR 2.97 [1.94–4.52]), male sex (OR 2.12 [1.54–3.6]) and smoking (OR 1.56 [1.01–2.39]) were significant risk factors for adenomas. Unexpectedly the mean consumption of alcohol, wine and beer, was significantly lower in subjects in whom adenomas were localized only in the rectum compared to those having adenomas in the sigmoid or in the proximal colon. Significant risk factors in subjects with hyperplastic polyps on univariate analysis were intake of > 15 g of ham and sausage/day (OR 3.70 [1.49–9.19]), smoking (OR 1.79 [1.04–3.06]) and male sex. In the multiple logistic regression only intake of > 15 g/day of ham + sausage and male sex were significant risk factors (OR 3.24 [1.23–140.8] and 1.83 [1.05–318], respectively). Conclusion When controlling for other potential risk factors, smoking was the only significant lifestyle risk factor for colorectal adenomas and the intake of ham and sausage > 15 g/day for hyperplastic polyps. The intake of alcohol, wine and beer were markedly higher in subjects with adenomas of the colon compared to those with adenomas in the rectum.
Keywords: Key words Alcohol – colon cancer – colorectal adenomas – colorectal polyps – nutrition – diet
Burgerstein’s handbook of nutrition micronutrients in the prevention and therapy of disease by Prof. Dr. med. Manfred James Müller (44-45).
Congress announcements (46-46).