Effect of milk fat globules on growth and metabolism in rats fed an unbalanced diet
We assessed the effects of supplementing milk fat globules (MFG) on the growth and development of the skeleton in rats fed a Western unbalanced diet (UBD). The UBD is high in sugar and fat, low in protein, fiber, and micronutrients, and negatively impacts health. The MFG—a complex structure secreted in milk—has a unique proteome and lipidome, and differs significantly from isolated dietary ingredients. Rats consuming the UBD exhibited growth retardation and disrupted bone structural and mechanical parameters; these were improved by supplementation with small MFG. The addition of small MFG increased the efficiency of protein utilization for growth, and improved trabecular and cortical bone parameters. Furthermore, consumption of UBD led to a decreased concentration of saturated fatty acids and increased levels of polyunsaturated fatty acids (PUFA), particularly omega-6 PUFA, in the serum, liver, and adipose tissue. The addition of small MFG restored PUFA concentration and the ratio of omega-6 to omega-3 PUFA in bone marrow and adipose tissue. Finally, large but not small MFG supplementation affected the cecal microbiome in rats. Overall, our results suggest that natural structure MFG supplementation can improve metabolism and bone development in rats fed an UBD, with the effects depending on MFG size, whereas the detrimental effects of an UBD on the microbiome were not mitigated by MFG supplementation. Overall design: 3 week old Sprague-Dawley rats were fed for 6 weeks with a control diet, UBD or UBD+MFG. After the sacrifice, caecal stool samples were collected and used for 16S rRNA sequencing of the V4 region using 515F–806R primers.