Osteoporosis risk is increased by bone marrow fat linked to blood triglycerides
Osteoporosis can have multiple contributing causes (calcium deficiency is usually not one of them). Excess accumulation of bone marrow fat promotes osteoporosis by inhibiting osteoblasts (cells that build up bone) while spurring on osteoclasts (cells that tear bone down). A study recently published in the journal Radiology offers evidence that bone marrow fat tracks liver and muscle fat, and can be predicted by the level of serum triglycerides. The authors set out to...
"......investigate the associations between ectopic and serum lipid levels and bone marrow fat, as a marker of stem cell differentiation, in young obese men and women, with the hypothesis that ectopic and serum lipid levels would be positively associated with bone marrow fat."
Here ectopic refers to fat in the liver and skeletal muscle (outside of the adipose tissue). Stem cell differentiation refers to the differentiation of bones cells that build bone up (osteoblasts) and tear it down (osteoclasts, which perform a necessary function must remain in balance with osteoblast activity). They used magnetic resonance spectroscopy to measure liver, muscle and bone marrow fat 106 healthy subjects of both sexes ranging in age from 19 to 45 years. They also calculated BMI, and measured serum cholesterol and triglyceride levels, and measures of insulin resistance. Their data reveal that serum triglycerides predict bone marrow fat:
"There was a positive correlation between bone marrow fat and IHL [intrahepatic lipids = liver fat], IMCL [intramyocellular lipids = muscle fat], and serum triglyceride level, independent of BMI, age, IR, and exercise status. High-density lipoprotein cholesterol levels were inversely associated with bone marrow fat content, independent of BMI, age, IR, and exercise status."
The authors conclude:
"Results of this study suggest that ectopic and serum lipid levels are positively associated with bone marrow fat in obese men and women."
Importantly, the authors further state as reported in Medscape Family Medicine:
"Lipids and lipoproteins are emerging as important regulators of skeletal physiologic characteristics and have been shown to inhibit osteoblast and to enhance osteoclast differentiation and survival...Because bone marrow fat is known to be inversely related to [bone mineral density], these results support the notion that ectopic and serum lipid levels are influenced by the same additional factors as bone marrow or may exert negative effects on bone."