Safety evaluation of a milk basic protein fraction

Bone mass protective potential mediated by bovine milk basic protein requires normal calcium homeostasis in mice

OBJECTIVES

Milk provide protective effects against bone loss caused by an impaired calcium balance. Although the effects of some elements have previously been confirmed, the involvement of milk basic protein (MBP) in bone mineral metabolism remains poorly characterized. Moreover, the importance of mineral nutrition sufficiency to establish the effect of MBP must be evaluated.

METHODS

First, to evaluate the physiological conditions required for MBP activity, we examined the bone and mineral phenotypes of mice that suffer from insufficient calcium absorption due to a lack of intestinal vitamin D signaling. Second, to determine whether vitamin D signaling affects the effect of MBP on bone resorption, in vitro osteoclastogenesis were assessed using bone marrow cells.

RESULTS

In mice with systemic vitamin D receptor (Vdr) inactivation, dietary MBP supplementation was unable to normalize hypercalcemia and hyperparathyroidism and failed to rescue bone mineralization impairments. In contrast, calcium and bone homeostasis responded to MBP supplementation when Vdr inactivation was restricted to the intestines. Hyperparathyroidism in intestine-specific Vdr knockout mice was also improved by MBP supplementation, along with a decrease in bone resorption in response to the level of serum tartrate-resistant acid phosphatase 5b. These results corresponded with a reduction in tartrate-resistant acid phosphatase-stained osteoclast numbers and the eroded surface on the tibia. MBP treatment dose-dependently suppressed osteoclastogenesis in cultured bone marrow macrophages regardless of vitamin D activity. These effects of MBP were blunted when parathyroid hormone was added to the culture medium, which is in line with the in vivo phenotype observed with systemic Vdr inactivation and suggests that severe hyperparathyroidism limits MBP activity in the bone.

CONCLUSIONS

Therefore, adaptive calcium homeostasis is an essential requirement when MBP exerts protective effects through the inhibition of bone resorption.

Safety evaluation of whey derived beta-lactoglobulin, Lacprodan® BLG

The safety of Lacprodan® BLG, a whey-based protein, was evaluated with respect to genotoxicity and sub-chronic toxicity according to regulatory requirements. Lacprodan® BLG did not show any mutagenic potential in a bacterial reverse mutation assay or any clastogenic or aneugenic potential in an in vitro micronucleus assay performed in human lymphocytes. In a sub-chronic toxicity study, groups of 10 male and 10 female Wistar rats received the test item orally by gavage for 90 days at dose levels of 100, 300 and 1000 mg/kg bw/day. A control group, also including 10 male and 10 female rats, received sterile water, as vehicle. No treatment-related clinical observations or toxicological effects on body or organ weights, food consumption, ophthalmic effects, hematology, clinical chemistry, fertility, urinalysis, or pathology were identified. Therefore, the no-observed-adverse-effect level (NOAEL) for Lacprodan® BLG in the 90-day toxicity study was established as 1000 mg/kg bw/day, corresponding to the highest dose level administered.

Acute oral toxicity study on Wistar rats fed microalgal protein hydrolysates from Bellerochea malleus

Protein hydrolysates and bioactive peptides from various protein sources have demonstrated their effectiveness for the prevention of illness and the improvement of symptoms from several diseases. In particular, the use of microalgae to generate bioactive peptides has received a growing interest because of their potential to be cultivated on non-arable land and high nutritional value. However, scant research is available on the toxicity of peptide-based preparations. The present study aims to evaluate the toxicity of microalgal protein hydrolysates (MPH) from one marine species of microalgae (Bellerochea malleus) to determine the feasibility of their use for functional food applications. Results showed that the oral administration of MPH at three doses (D1, 100 mg kg^-1 BW; D2, 400 mg kg^-1 BW; and D3, 2000 mg kg^-1 BW) to male Wistar rats did not induce any adverse effects or mortality up to13 days of treatment. Data analysis of relative organ weights and biochemical and hematological parameters did not show any significant differences between control and treated groups at the three doses investigated. Data from histopathological observations did not reveal any signs of major toxicity at the doses D1 and D2. However, mild signs of inflammation and necrosis were observed in the kidney of rats fed MPH at D3. All together, these results reveal the overall safety of MPH and provide new evidence for advocating their use for functional food or nutraceutical applications.

Short communication: Milk basic protein promotes proliferation and inhibits differentiation of mouse chondrogenic ATDC5 cells

It has been reported that the intake of milk basic protein (MBP) increases bone density by promoting bone formation and suppressing bone resorption. However, few studies have been done on MBP in cartilage, the tissue adjacent to bone. We therefore investigated the effect of MBP on a chondrocyte cell line, ATDC5. In a proliferative assay using the WST-1 method, the addition of 10, 100, and 1,000 µg/mL of MBP to ATDC5 cells significantly increased the cell number by about 1.2-, 1.5-, and 1.7-fold, respectively, compared with the control cells. The cell cycle analysis using flow-cytometry revealed that the proportion of S- and G₂/M-phase cells was increased but that of G₀/G₁ phase was decreased in a dose-dependent manner with MBP addition. We measured the alkaline phosphatase activity of MBP-treated ATDC5 cells to examine the differentiation stage of the cells. Alkaline phosphatase activity was suppressed in a dose-dependent manner with MBP addition and was especially drastic at higher doses of MBP (100 and 1,000 µg/mL). The Alizarin Red S staining intensity, the indicator for calcification of cells, was lower in the MBP-treated (100 µg/mL) cells than in nontreated control cells. In the reverse-transcription PCR experiment, the mRNA level of SRY-box containing gene 9 (Sox9) and type II collagen (Col2) was significantly increased in the MBP-treated cells compared with the control cells. A significant decrease of the mRNA level of runt-related transcription factor 2 (Runx2) and type X collagen (Col10) was also observed in the MBP-treated cells. These results suggested that MBP promoted the proliferation of chondrocytes by suppressing their differentiation toward calcification.

Safety of Whey basic protein isolates as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver an opinion on whey basic protein isolate as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is obtained by ion exchange chromatography of skimmed cow's milk. The applicant intends to market the NF in infant and follow-on formulae and meal replacement beverages, dietary foods for special medical purposes and as food supplements. The highest estimated intake of the NF based on the proposed uses and use levels would be 24.8 mg/kg body weight (bw) per day in infants and 27.8 in toddlers. The information provided on composition, specifications, production process and stability of the NF do not raise safety concerns. Taking into account the composition of the NF and the intended use levels, the Panel considers that the consumption of the NF is not nutritionally disadvantageous. The Panel considers that there is no concern with respect to genotoxicity. The no observed adverse effect level (NOAEL) of a subchronic 13-week rat study was 2000 mg/kg bw per day. Considering the source, the production process and nature of the NF, the Panel considers the margin of exposure (MOE) of 154 to be sufficient for the adult population (on a high-estimated intake of 13 mg/kg bw). For infants and toddlers, the MOE would be at least 81 and 72, respectively. Taking into account the composition of the NF, its source, the history of consumption of the main components of the NF, the production process and that the NOAEL in a subchronic rat study was the highest dose tested the Panel considers that also the MOE for infants and toddlers are sufficient. The Panel concludes that the novel food ingredient, whey basic protein isolate, is safe under the proposed uses and use levels.

Toxicological studies on plant proteins: a review

Nowadays, toxicological studies are contributing to human health more than ever. Reports on the toxicological studies of plant proteins, which are continuously growing in number in the literature, have been reviewed. Two important aspects are discussed: dietary safety evaluation, including toxicity tests and the maximum daily intake allowance, and the appropriate proportion in our daily diets of proteins from traditional foods and of new proteins from plant sources not traditionally employed as foods. Water hyacinth leaf proteins, sweet lupin proteins and canola proteins have not been shown to be toxic, although they are not traditionally employed as food proteins. These findings are very important for exploiting valuable new protein sources that are suitable for human or animal consumption and applicable to the food industry. Acutely toxic proteins, including lectins, ribosome-inactivating proteins, inhibitors of proteolytic enzymes and glycohydro-lases, have been isolated from plant materials and identified. Their toxicities and molecular characteristics have been described. The toxicity of proteins depends upon their specific native structures. Once they are denatured by appropriate treatment, such as heating, their toxicity can be reduced or even eliminated. These findings indicate that raw materials that contain this kind of toxic protein are not edible. However, after proper processing, they may be suitable for human or animal consumption. Although the toxicities of type 2 ribosome-inactivating proteins reported by different authors vary, the maximum dosages are still trace amounts.

Evaluation of the immunogenicity and in vivo toxicity of the antimicrobial peptide P34

Immunogenicity and toxicity of antimicrobial peptide P34 were evaluated in vivo. BALB/c mice were inoculated intraperitoneally with peptide P34 alone and associated with Freund's adjuvant. For acute toxicity testing, different concentrations of the peptide P34 (82.5, 165.0, 247.5 and 330.0mg/kg) were orally administered. To evaluate the sub-chronic toxicity the tested dose of 0.825 mg/kg/day of the peptide P34 or nisin were administered for 21 days. There were no hypersensitivity reactions or significant increase in antibody titer during the immunogenicity experiment or death of animals during the acute or sub-chronic toxicity tests. The LD(50) was higher than 332.3 ± 0.76 mg/kg. No significant changes in serum biochemical parameters were observed in the animals treated with the peptide P34 unlike nisin-treated group showed a significant increase in alanine transaminase levels in comparison to controls. The group treated with 0.825 mg/kg/day of nisin showed histological changes in the spleen, skin and liver. In the group treated with peptide P34 histological changes in the spleen were observed, with the presence of megakaryocytes. Few studies report the use of animal models to evaluate the in vivo toxicity of antimicrobial peptides and such investigation is an essential step to ensure it safe use in foods.