Is vaccenic acid (18:1t n-7) associated with an increased incidence of hip fracture? An explanation for the calcium paradox.
High calcium intake may increase hip fracture (HF) incidence. This phenomenon, known as the calcium paradox, might be explained by vaccenic acid (18:1t n-7, VA), the highly specific trans fatty acid (TFA) present in dairy products. First, we ecologically investigated the relationship between 18:1 TFA intake and HF incidence using data from 12 to 13 European countries collected before 2000; then we measured the effects of VA and elaidic acid (18:1t n-9, EA) on osteoblasts from goldfish scales (tissues very similar to mammalian bone), with alkaline phosphatase as a marker; and finally we measured the effect of VA on mRNA expression in the scales for the major bone proteins type I collagen and osteocalcin. HF incidence was significantly correlated with 18:1 TFA intake in men (r=0.57) and women (r=0.65). Incubation with 1μmol/L VA and EA for 48h significantly decreased alkaline phosphatase activity by 25% and 21%, respectively. Incubation of scales with 10μmol/L VA for 48h significantly decreased mRNA expression for type I collagen and osteocalcin (by about 50%). In conclusion, VA may be causatively related to HF and could explain the calcium paradox. It may be prudent to reduce 18:1 TFA intake, irrespective of trans positions, to prevent HF.
Department of Public Health, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama city, Toyama 930-0194, Japan. Electronic address: keihama@med.u-toyama.ac.jp.
Kei
K
Hamazaki
Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto-cho, Ishikawa 927-0553, Japan.
Nobuo
N
Suzuki
Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa city, Ishikawa 920-0942, Japan.
Kei-Ichiro
K
Kitamura
Department of Biology, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Ichikawa, Chiba 272-0827, Japan.
Atsuhiko
A
Hattori
Division of Clinical Application, Department of Clinical Sciences, Institute of Natural Medicine, University of Toyama, Toyama city, Toyama 930-0194, Japan(2).
Tetsuro
T
Nagasawa
Division of Clinical Application, Department of Clinical Sciences, Institute of Natural Medicine, University of Toyama, Toyama city, Toyama 930-0194, Japan(2); Department of Internal Medicine, Toyama Jonan Onsen Daini Hospital, Toyama city, Toyama 933-8271, Japan.
Miho
M
Itomura
Division of Clinical Application, Department of Clinical Sciences, Institute of Natural Medicine, University of Toyama, Toyama city, Toyama 930-0194, Japan(2); Department of Internal Medicine, Toyama Jonan Onsen Daini Hospital, Toyama city, Toyama 933-8271, Japan.
Tomohito
T
Hamazaki
D000369:Aged, 80 and over; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D024042:Collagen Type I / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006054:Goldfish; D006620:Hip Fractures / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D019301:Oleic Acid / Q000494:pharmacology; D009829:Oleic Acids / Q000009:adverse effects / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D015675:Osteocalcin / Q000235:genetics; D044242:Trans Fatty Acids / Q000008:administration & dosage*
D024042:Collagen Type I; D009829:Oleic Acids; D044242:Trans Fatty Acids; D015675:Osteocalcin; D019301:Oleic Acid; C011459:elaidic acid; C050413:11-octadecenoic acid; D002118:Calcium
Calcium paradox; Collagen type I; Dairy products; Goldfish scale; Hip fracture incidence; Milk; Osteoblasts; Osteocalcin; trans Fatty acid