Low dietary calcium and obesity: a comparative study in genetically obese and normal rats during early growth

A low calcium intake (LCaI) may predispose to obesity, and excessive fat mass may be detrimental to bone. The impact of Ca inadequacy would be greater in subjects predisposed to obesity. LCaI effect on obesity development during the rapid growth period was compared in two strains of rats: spontaneously obese IIMb/β (O) and Wistar (W). Pregnant rats were fed 0.5% (N) or 0.2% (L) of Ca (OLCa, ONCa, WLCa and WNCa). Male pups were fed the maternal diet until day 60.

Body composition, lipid profile, glucose homeostasis, 25 hydroxyvitamin D, Ca-phosphorus, and bone metabolism were evaluated.

BW and body fat were higher, whereas body protein was lower in OLCa versus ONCa (p < 0.05). OLCa presented the highest body fat, glucose, non-HDL and total cholesterol, TGL, insulin levels, and HOMA-IR, liver weight, and adipose perigonadal plus retroperitoneal pads (p < 0.05). WLCa did not exhibit an increase BW and only showed a slight change in body composition with minor biochemical alterations compared to WNCa (p < 0.05). Osteocalcin, CTX, and proximal tibia and lumbar spine BMDs were lower in O than in W rats fed the same Ca diet (p < 0.05). Body ash and Ca content, and total skeleton BMC/BW were lower in OLCa and WLCa versus their corresponding NCa groups (p < 0.05).

The negative effect of a low Ca diet on fat mass accumulation and lipid profile may be more evident in rats predisposed to obesity. Nevertheless, low CaI interferes with the normal glucose homeostasis leading to an increase in insulin resistance. Low CaI during early growth may be an obesogenic factor that may persist into adult life and may account for the development of obesity and some of its co-morbidities.