"During the last two decades a variety of food protein fragments has been demonstrated to elicit biological effects in various in vitro or in vivo test systems. A considerable part of these bioactive peptides are opioid receptor ligands , which may be regarded as exogenous supplements to the endogenous opioidergic systems of the human organism. Most of these foodderived opioid receptor ligands are fragments of the milk proteins alpha-, beta- or kappa-casein, alpha-lactalbumin, beta-lactoglobulin or lactotransferrin; however, also wheat gluten, rice albumin, bovine serum albumin or hemoglobin, i.e. possible constituents of meat, and even a protein from spinach could be demonstrated to contain fragments behaving like opioid receptor ligands. Practically all of these compounds display opioid agonist activity; only very few of them behave like opioid antagonists. Bioactive food protein derivatives have been termed “ food hormones”, which implies that these compounds display their bioactivities when released from food constituents, i.e. from their precursor molecules due to the action of gastrointestinal enzymes. The critical point in case of food protein-derived opioid receptor ligands is that only a minority of their bioactive effects demonstrated as yet has been observed upon oral or intragastric administration of these peptides or their precursor proteins and that most of these studies have been performed in animals. Thus, in terms of “evidence-based dietary supplementation” more studies are needed to prove effects of food protein-derived opioid receptor ligands or their precursors after oral administration in humans and, moreover, to prove a benefit for the consumers organism."
Gluten exorphin B5 stimulates prolactin secretion through opioid receptors located outside the blood-brain barrier.
Abstract
"Gluten exorphin B5 (GE-B5) is a food-derived opioid peptide identified in digests of wheat gluten. We have recently shown that GE-B5 stimulates prolactin (PRL) secretion in rats; this effect is abolished by preadministration of the opioid receptor antagonist naloxone. However, since the structure of naloxone allows it to cross the blood-brain barrier (BBB) and antagonize opioid effects centrally as well as peripherally, it could not established, on the basis of those data, if GE-B5-induced PRL release is exerted through sites located inside or outside the BBB. In this study, we sought to determine the site of action of GE-B5 on PRL secretion, by pretreating male rats with naloxone methobromide (NMB), an opioid antagonist that does not cross the BBB. Four groups of rats were given the following treatments: 1) intravenous vehicle; 2) intravenous GE-B5 (3 mg kg(-1) body weight); 3) intraperitoneal NMB (5 mg kg(-1) body weight), followed by vehicle; 4) NMB, followed by GE-B5. Blood samples for PRL were taken at intervals for 40 minutes after vehicle or GE-B5 administration. GE-B5 stimulated PRL secretion; the effect was statistically significant at time 20. NMB preadministration completely abolished PRL response. Our experiment indicates that GE-B5 stimulates PRL secretion through opioid receptors located outside the BBB. Since opioid peptides do not exert their effect on PRL secretion directly, but via a reduced dopaminergic tone, our data suggest that GE-B5 can modify brain neurotransmitter release without crossing the BBB."
Duodenal Infusion of Donor Feces for Recurrent Clostridium difficile.
Abstract
"Background Recurrent Clostridium difficile infection is difficult to treat, and failure rates for antibiotic therapy are high. We studied the effect of duodenal infusion of donor feces in patients with recurrent C. difficile infection. Methods We randomly assigned patients to receive one of three therapies: an initial vancomycin regimen (500 mg orally four times per day for 4 days), followed by bowel lavage and subsequent infusion of a solution of donor feces through a nasoduodenal tube; a standard vancomycin regimen (500 mg orally four times per day for 14 days); or a standard vancomycin regimen with bowel lavage. The primary end point was the resolution of diarrhea associated with C. difficile infection without relapse after 10 weeks. Results The study was stopped after an interim analysis. Of 16 patients in the infusion group, 13 (81%) had resolution of C. difficile-associated diarrhea after the first infusion. The 3 remaining patients received a second infusion with feces from a different donor, with resolution in 2 patients. Resolution of C. difficile infection occurred in 4 of 13 patients (31%) receiving vancomycin alone and in 3 of 13 patients (23%) receiving vancomycin with bowel lavage (P<0.001 for both comparisons with the infusion group). No significant differences in adverse events among the three study groups were observed except for mild diarrhea and abdominal cramping in the infusion group on the infusion day. After donor-feces infusion, patients showed increased fecal bacterial diversity, similar to that in healthy donors, with an increase in Bacteroidetes species and clostridium clusters IV and XIVa and a decrease in Proteobacteria species. Conclusions The infusion of donor feces was significantly more effective for the treatment of recurrent C. difficile infection than the use of vancomycin. (Funded by the Netherlands Organization for Health Research and Development and the Netherlands Organization for Scientific Research; Netherlands Trial Register number, NTR1177 .)."
The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease.
Abstract
"A fat diet, rich in saturated fatty acids (SFA) and low in polyunsaturated fatty acids (PUFA), is said to be an important cause of atherosclerosis andcardiovascular diseases (CVD). The evidence for this hypothesis was sought by reviewing studies of the direct link between dietary fats and atherosclerotic vascular disease in human beings. The review included ecological, dynamic population, cross-sectional, cohort, and case-controlstudies, as well as controlled, randomized trials of the effect of fat reduction alone. The positive ecological correlations between national intakes of total fat (TF) and SFA and cardiovascular mortality found in earlier studies were absent or negative in the larger, more recent studies. Secular trends of national fat consumption and mortality from coronary heart disease (CHD) in 18-35 countries (four studies) during different time periods diverged from each other as often as they coincided. In cross-sectional studies of CHD and atherosclerosis, one group of studies (Bantu people vs. Caucasians) were supportive; six groups of studies (West Indians vs. Americans, Japanese, and Japanese migrants vs. Americans, Yemenite Jews vs. Yemenite migrants; Seminole and Pima Indians vs. Americans, Seven Countries) gave partly supportive, partly contradictive results; in seven groups of studies (Navajo Indians vs. Americans; pure vegetarians vs. lacto-ovo-vegetarians and non-vegetarians, Masai people vs. Americans, Asiatic Indians vs. non-Indians, north vs. south Indians, Indian migrants vs. British residents, Geographic Study of Atherosclerosis) the findings were contradictory. Among 21 cohort studies of CHD including 28 cohorts, CHD patients had eaten significantly more SFA in three cohorts and significantly less in one cohort than had CHD-free individuals; in 22 cohorts no significant difference was noted. In three cohorts, CHD patients had eaten significantly more PUFA, in 24 cohorts no significant difference was noted. In three of four cohort studies of atherosclerosis, the vascular changes were unassociated with SFA or PUFA; in one study they were inversely related to TF. No significant differences in fat intake were noted in six case-control studies of CVD patients and CVD-free controls; and neither total or CHD mortality were lowered in a meta-analysis of nine controlled, randomized dietary trials with substantial reductions of dietary fats, in six trials combined with addition of PUFA. The harmful effect of dietary SFA and the protective effect of dietary PUFA on atherosclerosis and CVD are questioned."
