# Physiological Effects of Hydrolyzed Skim Milk and Probiotics on Osteoporosis Models
###### Abstract  
Osteoporosis, a skeletal metabolic disease characterized by low bone mineral density and deterioration of bone microarchitecture, frequently occurs in postmenopausal women older than 50 years. Milk and dairy products are essential calcium sources recommended for bone health. In this study, we analyzed the effects of skim milk and probiotics in an ovariectomized osteoporosis model. Body weight significantly increased, whereas the consumption of skim milk and probiotics significantly decreased (approximately 20%) in the ovariectomized models. In addition, the concentration of calcium was significantly 0.5 mg/dL higher in the skim-milk-with-probiotic group than in the ovariectomized group. The bone volume/tissue volume ratio, trabecular thickness, trabecular number, and trabecular separation were higher in the skim-milk and skim-milk-with-probiotic groups than in the ovariectomized group. Histological analysis of the small intestine revealed that the consumption of skim milk alone or in combination with probiotics increased the lengths of the villus, crypt, and serosa. These results verify the beneficial effects of milk products in osteoporosis models, which may enable higher milk and milk product consumption by older women.  
skim milk; probiotics; osteoporosis; ovariectomized model +
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than that in the same amount of human milk [8]. Other minerals found in milk, such as phosphorus, iodine, potassium, vitamins, proteins, and other nutrients, may be beneficial for skeletal growth and bone strength [9]. When the effects of dairy product consumption on human health were assessed, the bone mineral content (BMC) was found to be lower (approximately 5.6%) in adult women who had consumed less than one portion of milk weekly during childhood than in those who had consumed more than one portion [10].  
Prior studies examined the effects of milk or whey extracts on animals and surrogate markers in humans, such as bone remodeling markers or bone mineral density. Several observational studies using large cohorts also revealed the positive effects of milk on bone health or the risk of hip fracture [9].  
S skim-milk powder (SMP) is defined as whole milk in which the fat is removed. SMP contains 80% casein and 20% whey protein. [PERSON] et al. reported that SMP enhanced trabecular bone (TB) architecture compared to casein or whey in diet-induced obese rats [11]. As people age, their basal metabolic rate decreases, and if older people consume excessive milk for bone health, obesity can develop owing to milk fat.  
Probiotics and prebiotics are essential components of milk and dairy products that modulate bone turnover [12]. A recent study suggested the relevance of intestinal microbiota and bone health. Further, several studies have demonstrated that probiotics can prevent primary and secondary osteoporotic bone loss [12; 13]. In addition, probiotic-based compounds have been introduced in many fields of medicine such as dermatology, dentistry, and gastroenterology [14; 15; 16].  
Ovariectomized (OVX) animals are typical experimental models used to investigate postmenopausal osteoporosis caused by estrogen deficiency. OVX mouse and rat models have been widely used to evaluate and develop novel drugs for the treatment of postmenopausal osteoporosis [17]. Fermented soy skim milk attenuates bone loss in OVX mice and reduces the risk of osteoporosis [18]. Two probiotic strains were found to inhibit osteoporosis in an OVX mouse model, with _L. panacasei_ GKS6 outperforming _L. plantatum_ GKM3 [19].  
In this study, we determined the synergistic effects of skim milk and probiotics in an osteoporosis model. In particular, changes in body weight (BW), calcium concentration, lipid profiles, bone mineral density, bone mineral content, and length of the small intestine components were determined.