Wilson T A, Ausman L M, Lawton C W, Hegsted D M, Nicolosi R J
Department of Health and Clinical Science, Center for Chronic Disease Control and Prevention, University of Massachusetts, Lowell 01854-5125, USA.
J Am Coll Nutr. 2000 Oct;19(5):601-7. doi: 10.1080/07315724.2000.10718957.
Our laboratory has previously reported that the hypolipidemic effect of rice bran oil (RBO) is not entirely explained by its fatty acid composition. Although RBO has up to three times more serum cholesterol-raising saturated fatty acids (SATS) than some unsaturated vegetable oils, we hypothesized that its greater content of the unsaponifiables would compensate for its high SATS and yield comparable cholesterol-lowering properties to other vegetable oils with less SATS.
To study the comparative effects of different unsaturated vegetable oils on serum lipoprotein levels, nine cynomologus monkeys (Macaca fascicularis) were fed diets, for four weeks, in a Latin square design, containing rice bran, canola or corn oils (as 20% of energy) in a basal mixture of other fats to yield a final dietary fat concentration of 30% of energy. All animals were fed a baseline diet containing 36% of energy as fat with 15% SATS, 15% monounsaturated fatty acids (MONOS) and 6% polyunsaturated fatty acids (POLYS).
Despite the lower SATS and higher MONOS content of canola oil and the higher POLYS content of corn oil, RBO produced similar reductions in serum total cholesterol (TC) (-25%) and low density lipoprotein cholesterol (LDL-C) (-30%). In addition, as compared to the baseline diet, the reduction in serum TC and LDL-C cholesterol with RBO was not accompanied by reductions in high density lipoprotein cholesterol (HDL-C) which occurred with the other two dietary oils. Using predictive equations developed from data gathered from several studies with non-human primates, we noted that the observed serum TC and LDL-C lowering capabilities of the RBO diet were in excess of those predicted based on the fatty acid composition of RBO.
These studies suggest that non-fatty acid components (unsaponifiables) of RBO can contribute significantly to its cholesterol-lowering capability.
我们实验室之前报道过，米糠油（RBO）的降血脂作用不能完全由其脂肪酸组成来解释。尽管米糠油的血清胆固醇升高饱和脂肪酸（SATS）含量比一些不饱和植物油多两倍，但我们推测，其更高含量的不皂化物将弥补其高SATS含量，并产生与其他SATS含量较低的植物油相当的降胆固醇特性。
为研究不同不饱和植物油对血清脂蛋白水平的比较作用，9只食蟹猴（食蟹猕猴）按照拉丁方设计喂食四周，在其他脂肪的基础混合物中含有米糠油、菜籽油或玉米油（占能量的20%），以使最终膳食脂肪浓度达到能量的30%。所有动物喂食含36%能量为脂肪的基线饮食，其中15%为SATS，15%为单不饱和脂肪酸（MONOS），6%为多不饱和脂肪酸（POLYS）。
尽管菜籽油的SATS含量较低、MONOS含量较高，玉米油的POLYS含量较高，但米糠油使血清总胆固醇（TC）（-25%）和低密度脂蛋白胆固醇（LDL-C）（-30%）产生了类似的降低。此外，与基线饮食相比，米糠油降低血清TC和LDL-C胆固醇的同时，并未伴随其他两种食用油所出现的高密度脂蛋白胆固醇（HDL-C）降低。使用从多项非人类灵长类动物研究收集的数据建立的预测方程，我们注意到，米糠油饮食所观察到的血清TC和LDL-C降低能力超过了基于米糠油脂肪酸组成所预测的能力。
这些研究表明，米糠油的非脂肪酸成分（不皂化物）对其降胆固醇能力有显著贡献。
