Ima-Nirwana S, Ahmad Nazrun S, Yee LJ, Loh HC, Yew SF, Norazlina M, Abdul Gapor MT, Kamsiah J
Correspondence: Prof Ima Nirwana Soelaiman, imasoel@medic.ukm.my
ABSTRACT
Introduction The short-term and long- term effects of heated soy oil on bone metabolism in ovariectomised Sprague-Dawley rats were studied.
Methods Three-month-old female rats, were divided into five groups: normal control (NC); ovariectomised control (OVXC); ovariectomised and fed rat chow with added fresh soybean oil (SOF) or once-heated soy oil (SO1) or five-times-heated soy oil (SO5). Short-term parameters measured after one month were serum interleukin-6 (IL-6) and osteocalcin. Long-term parameters measured after six months were the structural bone histomorphometrical parameters. Vitamin E content in the soy oil subjected to the different heating treatments were also measured.
Results Rats in the SO5 group had higher levels of IL-6 after one month compared to the other four groups. Osteocalcin levels in the SO1 and SO5 groups remained high after treatment, while those in the NC and SOF groups declined. After six months, bone mass declined in the SO5 group. Vitamin E assay in the oils showed that levels of alpha-tocopherol decreased after heating the oil once and five times, while levels of gamma- and delta-tocopherols only declined after heating five times.
Conclusion Repeated heating of soy oil destroyed the tocopherols causing raised serum IL-6 and osteocalcin levels, leading to increased bone resorption and osteoporosis in the long term.
Keywords: bone metabolism, heated soy oil, oestrogen deficiency, soy oil, vitamin E
Singapore Med J 2007; 48(3): 200–206
