Oral bovine lactoferrin improves bone status of ovariectomized mice.

The aim of the present study was to evaluate the effect of dietary lactoferrin on bone metabolism in vivo using a postmenopausal animal model. We investigated whether bovine lactoferrin (bLF) ingestion could prevent bone loss in ovariectomized mice. Twelve-week-old female C3H mice either ovariectomized or sham operated were fed for 27 wk with the control diet (AIN-93M with 140 g of total milk protein as a protein source per kg of diet). Four groups of ovariectomized mice received diets including different concentrations of bLF (1, 5, 10, or 20 g of total milk protein were replaced by bLF). Ovariectomy induced a decreased uterine weight and a smaller gain of bone mineral density. Immunoreactive bLF was detected in the peripheral blood, and its concentration was related to the amount of bLF ingestion. bLF supplementation to the diet improved bone mineral density (BMD) and femoral failure load in a dose-dependent manner. We confirmed the direct effects of bLF in vitro using established and primary cultures of murine bone cells. Addition of bLF to the culture medium at a concentration of between 1 and 1,000 microg/ml stimulated both cell growth and differentiation of osteoblastic MC3T3 cells while inhibiting the growth of preosteoclastic RAW 267.4 cells. In primary culture of mixed bone cells, an enhanced osteoblast differentiation was associated with an inhibition of osteoclast differentiation at lower bLF concentrations (1-10 microg/ml). In conclusion, these findings suggest that dietary lactoferrin supplementation can have a beneficial effect on postmenopausal bone loss by modulating bone formation and resorption.

A high-protein, moderate-energy, regular cheesy snack is energetically compensated in human subjects.

Snacking is often regarded as a cause of overweight. However, the main issue is to determine whether the consumption of snacks leads to an increase in energy intake or whether a compensation phenomenon exists and maintains daily energy intake at a constant level. The objective of the present study was to determine whether the repeated consumption of a high-protein, moderate-energy, cheesy snack given as a preload 1 h before a meal altered energy intake at the next meal and then throughout the day, and if this kind of snack was energetically compensated. Normal-weight women (n 27) were recruited for the study. All subjects were healthy non-smokers, aged 18-60 years. The snacks consisted of portions of cheese containing 22 g protein, with an energy value of 836 kJ. Two types of snack were compared, differing in terms of the type of milk proteins they contained: the first contained casein only (CAS), while the second contained a mixture of casein and whey proteins (WHEY+CAS; 2:1). The principal finding of the present study was that the ingestion of the two snacks 1 h before lunch led to energy compensation of 83.1 (SEM 9.4) and 67.0 (SEM 16.4) % for WHEY+CAS and CAS respectively, at lunch, and 121.6 (SEM 36.5) and 142.1 (SEM 29.7) % for WHEY+CAS and CAS respectively, regarding the whole-day energy intake. In conclusion, the repeated consumption of a high-protein, moderate-energy, regular cheesy snack should not promote overweight because energy intake appears to be regulated during subsequent meals on the same day.

High-protein diets containing different milk protein fractions differently influence energy intake and adiposity in the rat.

This study was designed to determine whether (1) protein type and (2) the dietary carbohydrate to lipid content affected daily energy intake, body weight and adiposity in rats receiving high-protein diets ad libitum over a 25 d period. Each of the ten groups (n 8) consumed ad libitum one of the diets described below. A normal protein diet (P14C56L30, containing whole milk protein) and nine high-protein diets were used. The composition of the high-protein diets varied in terms of two parameters: macronutrient composition and protein type. Three macronutrient compositions (P55C35L10, P55C15L30 and P55L45) combined with three protein types (Milk, Whey and betaLac) allowed us to test nine diets. The results show that both protein type (betaLac > Whey > Milk) and the carbohydrate to lipid ratio (P55L45>P55C35L10 or P55C15L30) modulated reductions in energy intake, body weight and adiposity in rats receiving high-protein diets ad libitum, when compared with rats fed a normal diet under the same conditions. By contrast, blood lipid profiles were mainly influenced by the carbohydrate to lipid ratio (P55C15L30>P55L45 or P55C35L10). Moreover, betaLac protein was also the most efficient in tending to preserve lean body mass at the expense of fat mass, and improve blood metabolism hormones (insulin, leptin). Taken together, the present results show that whey-derived protein sources, and particularly beta-lactoglobulin-enriched fraction, are of considerable value because of their ability to reduce both body weight gain and the adiposity index.