Protein v. enzymic protein hydrolysates. Nitrogen utilization in starved rats

Effects of Replacing Fish Meal with Enzymatic Cottonseed Protein on the Growth Performance, Immunity, Antioxidation, and Intestinal Health of Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

The dietary effects of replacing fish meal with enzymatic cottonseed protein (ECP) on the growth performance, immunity, antioxidant, and intestinal health of Chinese soft-shelled turtles have not been explored. An eight-week feeding trial was conducted with a quadruplicated group of turtles (3.44 ± 0.01 g) that were randomly assigned to 16 cages (0.6 m × 0.6 m × 0.6 m) with 30 turtles that were stocked in each cage. Four dietary groups were fed with diets supplemented with 0, 2%, 4%, and 6% (ECP0 group (control group), ECP2 group, ECP4 group, ECP6 group) of enzymatic cottonseed protein replacing fishmeal. The present study illustrated that the final weight and WG in the ECP2 and ECP4 groups were significantly increased (P < 0.05) compared with the control group. The ECP2, ECP4, and ECP6 groups significantly reduced the feed coefficient (P < 0.05) and significantly increased the SGR (P < 0.05). The serum TP and ALB of the ECP4 group were significantly increased (P < 0.05). The ECP2, ECP4, and ECP6 groups significantly increased the activity of intestinal pepsin (P < 0.05), and the activity of intestinal lipase of the EPC4 group was significantly increased (P < 0.05). The intestinal villus height of the EPC4 group and EPC6 group, the villus width of the EPC2 group and EPC4 group, and the intestinal muscle thickness of the EPC4 group were significantly increased (P < 0.05). At the same time, replacing fishmeal with enzymatic cottonseed protein also affected the intestinal inflammation-related genes compared with the control group. Besides that, the expression of the IL-10 gene in the experimental group was significantly upregulated (P < 0.05). Nevertheless, the expression of TNF-α and IL-8 genes in the ECP2 group and TNF-α and IL-1β genes in the ECP4 group was significantly downregulated (P < 0.05). In summary, replacing fish meal with enzymatic cottonseed protein positively affects the growth, immunity, and intestinal health of Chinese soft-shelled turtles. The appropriate proportion of enzymatic cottonseed protein to replace fish meal in turtle feed is 4%.

The role of protein hydrolysates for exercise-induced skeletal muscle recovery and adaptation: a current perspective

The protein supplement industry is expanding rapidly and estimated to have a multi-billion market worth. Recent research has centred on understanding how the manufacturing processes of protein supplements may impact muscle recovery and remodeling. The hydrolysed forms of protein undergo a further heating extraction process during production which may contribute to amino acids (AA) appearing in circulation at a slightly quicker rate, or greater amplitude, than the intact form. Whilst the relative significance of the rate of aminoacidemia to muscle protein synthesis is debated, it has been suggested that protein hydrolysates, potentially through the more rapid delivery and higher proportion of di-, tri- and smaller oligo-peptides into circulation, are superior to intact non-hydrolysed proteins and free AAs in promoting skeletal muscle protein remodeling and recovery. However, despite these claims, there is currently insufficient evidence to support superior muscle anabolic properties compared with intact non-hydrolysed proteins and/or free AA controls. Further research is warranted with appropriate protein controls, particularly in populations consuming insufficient amounts of protein, to support and/or refute an important muscle anabolic role of protein hydrolysates. The primary purpose of this review is to provide the reader with a current perspective on the potential anabolic effects of protein hydrolysates in individuals wishing to optimise recovery from, and maximise adaptation to, exercise training.

Effects of fermented corn gluten meal on growth performance, serum parameters, intestinal morphology, and immunity performance of three-yellow broilers

A study was conducted to determine the effects of a diet containing solid-state fermented corn gluten meal (FCGM) with Bacillus natto and Lactobacillus on the growth performance, serum parameters, immune indices, and intestinal morphology of three-yellow broilers. A total of 450 one-d-old three-yellow male broilers were randomly allocated into three dietary treatment groups: control (without FCGM), T1, and T2 [5% and 10% replacement with corn gluten meal (CGM) and FCGM, respectively]. Ten replications per treatment and 15 birds per repeat were utilized. The results showed that the FCGM had a lower neutral detergent fiber content and higher small peptide content than the CGM. The average daily gain values, globulin content, the thymus and spleen indices of three-yellow broilers fed 5% and 10% FCGM were significantly higher (P < 0.05) than those of the control group, and the three-yellow broilers that were fed 10% FCGM increased more than those that were fed 5% FCGM (P < 0.05). The villus lengths and the ratios of the villus height to crypt depth (V:C) of the duodenum of three-yellow broilers fed 5% and 10% FCGM were significantly higher than those of the control group (P < 0.05). From this study, it can be concluded that the productivity performances of three-yellow broilers fed with 5% FCGM and 10% FCGM increased, and with the additive level increase in the diet, increases of the productivity performance were observed.

Influence of an ω3-fatty acid-enriched enteral diet with and without added glutamine on the metabolic response to injury in a rat model of prolonged acute catabolism

OBJECTIVE

In critically ill patients, acute injury alters gut function, causing greater risk for sepsis and malnutrition. Peptide-enriched diets may promote nitrogen absorption, whereas ω3-enriched diets reduce alterations in gut barrier function. The aim of this study was to assess the effectiveness of a peptide- and ω3-enriched diet on the metabolic response to injury and the gut barrier function in a model of prolonged catabolism in the rat. Given the intestinal trophic effect of glutamine, we tested for a synergistic effect of glutamine.

METHODS

We randomized 40 male Sprague-Dawley rats (250 g) into four groups to enterally receive a standard high-protein diet (S), or a peptide- and ω3-enriched diet either alone (IMN) or supplemented with glutamine and alanine supplied as dipeptide (DIP) or as free amino acids (AAs) for 4 d. Metabolic response to injury was induced by turpentine injections on days 1 and 3. At sacrifice, nutritional and inflammatory biomarkers and intestinal and liver function were assessed.

RESULTS

Weight gain (+45-62%) and nitrogen balance (+33-56%) were significantly higher in all groups than in the S group. In jejunal mucosa, total glutathione was significantly higher (+20-30%) and myeloperoxidase activity significantly lower in all groups compared with the S group. Hepatic triacylglycerol content was significantly lower in the AA (0.30 ± 0.04 μM/g) and DIP (0.43 ± 0.08 μM/g) groups than in the S group (0.71 ± 0.08 μM/g).

CONCLUSIONS

In this model of prolonged catabolism, compared with a standard diet, a peptide- and ω3-enriched diet improved metabolic response to injury, with better nitrogen balance and weight recovery, and decreased intestinal myeloperoxidase activity. Only marginal additional effects of glutamine supplementation were observed with decreased hepatic fat content.

Growth and Tolerance of Preterm Infants Fed a New Extensively Hydrolyzed Liquid Human Milk Fortifier

OBJECTIVES

This study was a comparison of growth and tolerance in premature infants fed either standard powdered human milk fortifier (HMF) or a newly formulated concentrated liquid that contained extensively hydrolyzed protein.

METHODS

This was an unblinded randomized controlled multicenter noninferiority study on preterm infants receiving human milk (HM) supplemented with 2 randomly assigned HMFs, either concentrated liquid HMF containing extensively hydrolyzed protein (LE-HMF) or a powdered intact protein HMF (PI-HMF) as the control. The study population consisted of preterm infants ≤33 weeks who were enterally fed HM. Infants were studied from the first day of HM fortification until day 29 or hospital discharge, whichever came first.

RESULTS

A total of 147 preterm infants were enrolled. Noninferiority was observed in weight gain reported in the intent-to-treat (ITT) analysis was 18.2 and 17.5 g · kg(-1) · day(-1) for the LE-HMF and PI-HMF groups, respectively. In an a priori defined subgroup of strict protocol followers (n = 75), the infants fed LE-HMF achieved greater weight over time than those fed PI-HMF (P = 0.036). The LE-HMF group achieved greater linear growth over time compared to the PI-HMF (P = 0.029). The protein intake from fortified HM was significantly higher in the LE-HMF group compared with the PI-HMF group (3.9 vs 3.3 g · kg(-1) · day(-1), P < 0.0001). Both fortifiers were well tolerated with no significant differences in overall morbidity.

CONCLUSIONS

Both fortifiers showed excellent weight gain (grams per kilograms per day), tolerance, and low incidence of morbidity outcomes with the infants who were strict protocol followers fed LE-HMF having improved growth during the study. These data point to the safety and suitability of this new concentrated liquid HMF (LE-HMF) in preterm infants. Growth with this fortifier closely matches the recent recommendations for a weight gain of >18 g · kg(-1) · day(-1).

Whey protein: The “whey” forward for treatment of type 2 diabetes?

A cost-effective nutritional approach to improve postprandial glycaemia is attractive considering the rising burden of diabetes throughout the world. Whey protein, a by-product of the cheese-making process, can be used to manipulate gut function in order to slow gastric emptying and stimulate incretin hormone secretion, thereby attenuating postprandial glycaemic excursions. The function of the gastrointestinal tract plays a pivotal role in glucose homeostasis, particularly during the postprandial period, and this review will discuss the mechanisms by which whey protein slows gastric emptying and stimulates release of gut peptides, including the incretins. Whey protein is also a rich source of amino acids, and these can directly stimulate beta cells to secrete insulin, which contributes to the reduction in postprandial glycaemia. Appetite is suppressed with consumption of whey, due to its effects on the gut-brain axis and the hypothalamus. These properties of whey protein suggest its potential in the management of type 2 diabetes. However, the optimal dose and timing of whey protein ingestion are yet to be defined, and studies are required to examine the long-term benefits of whey consumption for overall glycaemic control.

Effect of starvation and refeeding on biochemical and immunological status of Balb/c mice: an experimental model of malnutrition

CONTEXT

Although new methods for the induction of malnutrition disorders in laboratory animals have been developed, the bulk of the models described in the literature are essentially based on dietary restriction/starvation principle. In this context, little data are available about the metabolic and the immune system parameters of Balb/c mice under starvation/refeeding.

OBJECTIVE

This study examined the effects of starvation and refeeding on the biochemical and immunological status of undernourished Balb/c mice.

METHODS

Female Balb/c mice, weighing 20 g, were starved for 3 days and then refed with commercial pelleted diet for 8 days. The variables considered were as follows: body weight; serum protein and amino acid concentrations; liver protein content, and cholinesterase and arginase activities; jejunal protein and DNA contents as well as oligosaccharidase levels; hematological parameters (bone marrow and peripheral blood cellularity); peritoneal macrophage activation; and humoral and cell-mediated immune functions.

RESULTS

Profound alterations in both biochemical and immunological conditions appeared after the starvation period. Refeeding resulted in the normalization of serum albumin levels, the intestinal DNA content and the gut-mucosal associated enzymatic activities, the blood lymphocyte counts, and the number of peritoneal macrophages. The markers of liver metabolic function (cholinesterase and arginase activities), and those of bone marrow hemopoiesis and the adaptive immune response (T-dependent antibody titres and delayed-type hypersensitivity response) remained altered after refeeding compared with control mice.

CONCLUSION

These findings suggest that fasted mice can be used as an animal model of acute starvation that might prove useful in evaluating the effectiveness of nutritional and immunopharmacological interventions.

Ultra high temperature treatment, but not pasteurization, affects the postprandial kinetics of milk proteins in humans

Although the chemical and physical modifications to milk proteins induced by technological treatments have been characterized extensively, their nutritional consequences have rarely been assessed in humans. We measured the effect of 2 technological treatments on the postprandial utilization of milk nitrogen (N), pasteurization (PAST) and ultra high temperature (UHT), compared with microfiltration (MF), using a sensitive method based on the use of milk proteins intrinsically labeled with (15)N. Twenty-five subjects were studied after a 1-wk standardization of their diet. On the day of the investigation, they ingested a single test meal corresponding to 500 mL of either MF, PAST, or UHT defatted milk. Serum amino acid (AA) levels as well as the transfer of (15)N into serum protein and AA, body urea, and urinary urea were determined throughout the 8-h postprandial period. The kinetics of dietary N transfer to serum AA, proteins, and urea did not differ between the MF and PAST groups. The transfer of dietary N to serum AA and protein and to body urea was significantly higher in UHT than in either the PAST or MF group. Postprandial deamination losses from dietary AA represented 25.9 +/- 3.3% of ingested N in the UHT group, 18.5 +/- 3.0% in the MF group, and 18.6 +/- 3.7% in the PAST group (P < 0.0001). The higher anabolic use of dietary N in plasma proteins after UHT ingestion strongly suggests that these differences are due to modifications to digestive kinetics and the further metabolism of dietary proteins subsequent to this particular treatment of milk.

Utilisation of Chlorella vulgaris cell biomass for the production of enzymatic protein hydrolysates

Studies on enzymatic hydrolysis of cell proteins in green microalgae Chlorella vulgaris 87/1 are described. Different proteases can be used for production of hydrolysates from ethanol extracted algae. The influence of reaction parameters on hydrolysis of extracted biomass with pancreatin was considered, and the composition of hydrolysates (Cv-PH) was investigated in relation to the starting materials. Significant changes in the degree of hydrolysis were observed only during the first 2h and it remained constant throughout the process. An enzyme-substrate ratio of 30-45 units/g algae, an algae concentration of 10-15% and pH values of 7.5-8.0 could be recommended. Differences in the chromatographic patterns of Cv-PH and a hot-extract from Chlorella biomass were observed. Adequate amounts of essential amino acids (44.7%) in relation to the reference pattern of FAO for human nutrition were found, except for sulfur amino acids. Cv-PH could be considered as a potential ingredient in the food industry.

The effect of different protein hydrolysate/carbohydrate mixtures on postprandial glucagon and insulin responses in healthy subjects

OBJECTIVES

To study the effect of four protein hydrolysates from vegetable (pea, gluten, rice and soy) and two protein hydrolysates from animal origin (whey and egg) on glucagon and insulin responses.

SUBJECTS/METHODS

Eight healthy normal-weight male subjects participated in this study. The study employed a repeated-measures design with Latin square randomization and single-blind trials. Protein hydrolysates used in this study (pea, rice, soy, gluten, whey and egg protein hydrolysate) consisted of 0.2 g hydrolysate per kg body weight (bw) and 0.2 g maltodextrin per kg bw and were compared to maltodextrin alone. Postprandial plasma glucose, glucagon, insulin and amino acids were determined over 2 h.

RESULTS

All protein hydrolysates induced an enhanced insulin secretion compared to maltodextrin alone and a correspondingly low plasma glucose response. A significant difference was observed in area under the curve (AUC) for plasma glucagon between protein hydrolysates and the maltodextrin control drink (P<0.05). Gluten protein hydrolysate induced the lowest glucagon response.

CONCLUSIONS

High amino-acid-induced glucagon response does not necessarily go together with low insulin response. Protein hydrolysate source affects AUC for glucagon more profoundly than for insulin, although the protein load used in this study seemed to be at lower level for significant physiological effects.

Effect of protein source and resistance training on body composition and sex hormones

Background

Evidence suggests an inverse relationship between soy protein intake and serum concentrations of male sex hormones. Anecdotal evidence indicates that these alterations in serum sex hormones may attenuate changes in lean body mass following resistance training. However, little empirical data exists regarding the effects of soy and milk-based proteins on circulating androgens and exercise induced body composition changes.

Methods

For 12 weeks 20 subjects were supplemented with 50 g per day of one of four different protein sources (Soy concentrate; Soy isolate; Soy isolate and whey blend, and Whey blend only) in combination with a resistance-training program. Body composition, testosterone, estradiol and sex hormone binding globulin (SHBG) were measured at baseline and week 12.

Results

Protein supplementation resulted in a significant increase in lean body mass independent of protein source (0.5 ± 1.1 and 0.9 ± 1.4 kg, p = 0.006, p = 0.007). No significant differences were observed between groups for total and free testosterone, SHBG, percentage body fat, BMI or body weight. The Testosterone/Estradiol ratio increased across all groups (+13.4, p = 0.005) and estradiol decreased (p = 0.002). Within group analysis showed significant increases in the Testosterone/Estradiol ratio in soy isolate + whey blend group (+16.3, p = 0.030). Estradiol was significantly lower in the whey blend group (-9.1 ± 8.7 pg/ml, p = 0.033).

Conclusion

This investigation shows that 12 week supplementation with soy protein does not decrease serum testosterone or inhibit lean body mass changes in subjects engaged in a resistance exercise program.

The effects of inulin supplementation of diets with or without hydrolysed protein sources on digestibility, faecal characteristics, haematology and immunoglobulins in dogs

Dogs with food allergy are often treated by giving a diet with hydrolysed protein sources. Prebiotics might also be successful in prevention and treatment of allergic disease through their effect on the colonic microflora, analogous to studies on probiotics in allergic children. The present study was set up to investigate the effect of supplementing inulin (IN) to commercial hypoallergenic dog diets on apparent nutrient digestibility, faecal characteristics, haematology and Ig in dogs. Supplementation of 3 % IN did not affect faecal pH, food and water intake and urine production. Compared with the intact protein diet with a limited number of ingredients (L), the diet with a hydrolysed protein source (H) resulted in an increased water intake (P<0·001), which could be due to the osmotic effect of free amino acids. Faeces production was increased by IN due to increased faecal moisture content. Increased faeces production on the H diet was mainly due to a higher DM excretion. Subsequently, the apparent digestibility coefficient (ADC) of DM was lower in the H diet group. A similar result was noted for ADC of diethyl ether extract and crude ash. The ADC of crude protein was higher in the H diet group, whereas IN decreased the ADC of crude protein. Differences in the ADC of crude protein among the different diets disappeared after correction for a higher faecal biomass, except for the dogs fed the L + IN diet. Total faecal IgA concentrations were lower in the H group (P<0·05) because of lower antigenic stimulation of hydrolysed protein, which implies that hydrolysed protein is really hypoallergenic. The present study indicates that the use of hydrolysed protein diets for canine food allergy treatment can affect digestibility and that combination with IN affected apparent protein digestibility but not IgA response.

Pancreatic development in newborn guinea pigs fed intact or low-hydrolyzed protein formulas

AIM

To evaluate pancreatic development in newborn guinea pigs fed since birth intact or low-hydrolyzed protein formulas compared with breast milk.

METHODS

Forty-five newborn guinea pigs were allocated to three feeding regimens: breast milk (n=15) and two isocaloric isonitrogen milk formulas containing intact (n=15) or low-hydrolyzed proteins (n=15). Body weight and food consumption were recorded every day. After 8 days, one third of pups from each group was killed, and the remaining animals were weaned. Another third was killed on day 14, and the remainders were killed on day 20. Zymogen storage was evaluated on pancreatic sections, whereas DNA and RNA concentrations were measured by a fluorometric method.

RESULTS

Compared with breast fed pups, both groups of artificially fed animals showed lower weight gain during the first 2 weeks of life but not after weaning. Both formulas fed groups had significantly lower amount of zymogen granules in pancreatic acinar cells at 8 and 14 days of life. This reduction was still present at day 20 in intact protein formula but not in low-hydrolyzed protein formula fed animals in which higher RNA/DNA ratio was also observed compared with breast fed pups.

CONCLUSION

In newborn guinea pigs, artificial feeding is associated with reduced zymogen storage at days 8 and 14 of life. After weaning, cellular content of zymogen granules is comparable with breast fed pups only in low-hydrolyzed protein formula fed animals, even in the presence of some evidence of pancreatic hypoplasia.

Development of a rapid and convenient method to purify mucins and determine their in vivo synthesis rate in rats

The intestinal mucoprotein synthesis rate was measured in vivo for the first time. For this, a rapid, reproducible, and convenient method to purify mucoproteins from large numbers of intestinal samples at the same time was developed. The method takes advantage of both the high mucin resistance to protease activities due to their extensive glycosylations and the high mucin molecular size. Intestinal homogenates were partially digested with Flavourzyme. Nonprotected proteins partially degraded were easily separated from mucoproteins by small gel filtration chromatography using Sepharose CL-4B. Electrophoretically pure mucins were obtained. Their amino acid composition was typical of purified intestinal epithelial mucins. The mucoprotein synthesis rate was determined in vivo in rats using the flooding dose method with the stable isotope L-[1-13C]valine. Free L-[1-13C]valine enrichments in the intracellular pool were determined by GC-MS. L-[1-13C]valine enrichments into purified mucoproteins or intestinal mucosal proteins were measured by gas chromatography-combustion-isotope ratio mass spectrometry. In rats, we found that the gut mucosa protein synthesis rate (%/day) decreased regularly from duodenum (122%/day) to colon (43%/day). In contrast, mucoprotein fractional synthesis rates were in the same range along the digestive tract, between 112%/day (colon) and 138%/day (ileum).

Plasma glucagon and insulin responses depend on the rate of appearance of amino acids after ingestion of different protein solutions in humans

To find out whether the hormonal response to feeding with protein solutions is influenced by the nature and degree of protein fractionation, we examined insulin and glucagon responses after intake of protein solutions containing the same amount of nitrogen (2.9 g each) in three men and three women. Four test meals (600 mL) [glucose (419 kJ/L), pea (PPH) and whey peptide hydrolysates (WPH) (921 and 963 kJ/L, respectively) and a cow's milk solution (MS) containing complete milk proteins (2763 kJ/L)] were tested. Peptide hydrolysates elicited a faster increase in venous plasma amino acids than did MS (P < 0.05). Despite the higher carbohydrate content of the MS, the peptide hydrolysates elicited a peak insulin response that was two and four times greater than that evoked by the MS and glucose solutions, respectively (P < 0.05). The insulin response was closely related to the increase in plasma amino acids, especially leucine, isoleucine, valine, phenylalanine and arginine, regardless of the rate of gastric emptying. The three protein solutions elicited similar increases of plasma glucagon; however, the response was fastest for both peptide hydrolysates (P < 0.05) and more prolonged for the MS (P < 0.05). The glucagon response was linearly related to the increase in plasma amino acids, regardless of the rate of gastric emptying or meal composition (r = 0.93, r = 0.96 and r = 0.78, all P < 0.05, for the PPH, WPH and MS). Among the plasma amino acids, tyrosine (r = 0.82-0.98, P < 0.05) and methionine (r = 0.98, P < 0.001) were most closely related to the plasma glucagon response. This study shows that the glucagon response to feeding with protein solutions depends on the increase in plasma amino acid concentrations. The combined administration of glucose and peptide hydrolysates stimulates a synergistic release of insulin, regardless of the protein source.

Neither glutamine nor arginine supplementation of diets increase glutamine body stores in healthy growing rats

The aim of the work was to resolve whether glutamine and arginine supplemented diets affect plasma and tissue (muscle, liver and intestinal mucosa) glutamine concentrations, as well as glutaminase and glutamine synthetase specific activities. The trial was performed in growing rats fed 10% protein diets for 3 weeks. Protein sources were: whey proteins (W); whey proteins+free glutamine (WG); whey proteins+arginine (WA); and casein+wheat protein hydrolysate+acid whey (39:39:22), as source containing protein-bound glutamine (CGW). Rats fed the control diet (6.4% glutamine) (W) showed comparable glutamine body stores to those of rats fed the WG diet. In fact, glutamine sup- plementation down-regulated the hepatic glutamine synthetic capacity of growing rats (W/WG: 6.8+/-0.3 vs 6.0+/-0.2 nmol/min/mg protein). Arginine supplementation of the diet (up to 9% of the protein content) resulted in a decrease in plasma and tissue glutamine concentrations (W/WA: plasma, 1218+/-51 vs 1031+/-48 micromol/L; liver 7.5+/-0.4 vs 6.5+/-0.2 micromol/g; muscle: 5.7+/-0.2 vs 4.0+/-0.2 micromol/g). These data suggest that glutamine supplementation of the diet does not increase plasma and tissue glutamine concentrations in healthy growing rats, while the addition of arginine to the diet decreases glutamine body stores.

Special formulas in infant nutrition: a review

Special formulas should only be used by medical prescription and for those lactating infants with diagnosed nutritional problems. Lactose-free formulas or those based on soy are the logical choice when the exclusion of lactose from the diet is considered necessary. At present, there is no concensus on the appropriateness of soy formulas for the treatment and prevention of nutritional allergies and current opinion seems to favour hydrolyzed protein formulas. High-degree protein hydrolysate formulas are used to treat lactating infants with an allergy to cow milk proteins or with serious nutritional problems. These formulas are not without risk, as they may contain residual epitopes capable of provoking a severe allergic reaction. Before using these formulas, allergenicity tests should be performed, particularly for highly sensitive infants. The unpleasant taste and high cost of these formulas, in addition to possible nutritional problems, limit their use in the prevention of atopic disease, although their efficacy is well established. Partially protein hydrolysate formulas are only used for preventive purposes and are not suitable for lactating infants with a proven allergy to cow milk. Although these formulas can reduce the incidence or delay the appearance of certain atopic symptoms, they have not been shown to prevent IgE-mediated allergic reactions to cow's milk and so their effectiveness is open to question.