Herron Kristin L, Vega-Lopez Sonia, Conde Karin, Ramjiganesh Tripurasundari, Roy Suheeta, Shachter Neil S, Fernandez Maria Luz
Department of Nutritional Sciences, University of Connecticut, Storrs 06269, USA.
J Am Coll Nutr. 2002 Jun;21(3):250-8. doi: 10.1080/07315724.2002.10719218.
Cholesterol is the dietary component that has elicited the most public interest in conjunction with coronary heart disease. However, the impact of excess dietary cholesterol intake on plasma cholesterol levels cannot be accurately predicted; therefore, its role in disease progression is not straightforward. Individual response variation can be due to factors such as ethnicity, hormonal status, obesity and genetic predisposition.
The purpose of this study was to evaluate the differences that occur within the plasma compartment of normolipidemic pre-menopausal women, classified based on their response to a high dietary cholesterol challenge.
We recruited 51 pre-menopausal women (29 Caucasian and 22 of Hispanic origin) aged 18 to 49 years with initial plasma cholesterol concentrations ranging from 3.62 to 5.17 mmol/L. Using a cross-over research design, women were randomly allocated to an egg (640 mg additional dietary cholesterol per day) or placebo group (0 mg additional dietary cholesterol per day) initially, and the two 30 day periods were separated by a three-week washout.
An initial evaluation of the ethnicity effects revealed elevations in both plasma LDL-C (p < 0.0001) and HDL-C (p < 0.001) concentrations in both Hispanics and Caucasians during the high dietary cholesterol period. However, these increases were not accompanied by a change in the LDL/HDL ratio. Subjects were then classified as hypo- (< 0.05 mmol/L increase in total plasma cholesterol per each additional 100 mg of dietary cholesterol consumed per day) or hyper-responders (> or =0.06 mmol/L increase in total blood cholesterol per each additional 100 mg of dietary cholesterol consumed per day), based on their reaction to the additional dietary cholesterol provided. Hypo-responders did not experience an increase in LDL-C or HDL-C during the egg period, while both lipoproteins were elevated in hyper-responders. However, the LDL/HDL ratio, an important parameter of coronary heart disease risk, was maintained for all subjects during the egg period independent of response. Furthermore, hyper-responders had higher concentrations of apo C-III (p < 0.001), apo B (p < 0.001) and cholesterol ester transfer protein (CETP) (p < 0.05) during this period.
These data revealed that excess dietary cholesterol does not increase the risk of developing an atherogenic lipoprotein profile in pre-menopausal women, regardless of their response classification. Although the addition of 640 mg of cholesterol to the diet did result in an increase in plasma cholesterol in hyperresponders, the LDL/HDL ratio was maintained. This result, accompanied by increases in CETP activity, leads to the speculation that hyper-responders may process the excess cholesterol in the plasma compartment through an enhancement of the reverse cholesterol transport pathway. With this mechanism identified, further measurement of additional parameters is needed to verify this conclusion.
胆固醇是与冠心病相关联且最引发公众关注的膳食成分。然而，过量膳食胆固醇摄入对血浆胆固醇水平的影响无法准确预测；因此，其在疾病进展中的作用并不简单直接。个体反应差异可能归因于种族、激素状态、肥胖和遗传易感性等因素。
本研究旨在评估血脂正常的绝经前女性血浆成分内基于对高膳食胆固醇挑战的反应分类所出现的差异。
我们招募了51名年龄在18至49岁的绝经前女性（29名白种人和22名西班牙裔），初始血浆胆固醇浓度范围为3.62至5.17 mmol/L。采用交叉研究设计，女性最初被随机分配到鸡蛋组（每天额外摄入640毫克膳食胆固醇）或安慰剂组（每天额外摄入0毫克膳食胆固醇），两个30天周期之间有三周的洗脱期。
对种族效应的初步评估显示，在高膳食胆固醇期间，西班牙裔和白种人的血浆低密度脂蛋白胆固醇（LDL-C）（p < 0.0001）和高密度脂蛋白胆固醇（HDL-C）（p < 0.001）浓度均升高。然而，这些升高并未伴随LDL/HDL比值的变化。然后根据受试者对额外提供的膳食胆固醇的反应，将其分类为低反应者（每天每额外摄入100毫克膳食胆固醇，总血浆胆固醇增加< 0.05 mmol/L）或高反应者（每天每额外摄入100毫克膳食胆固醇，总血胆固醇增加≥0.06 mmol/L）。在鸡蛋期，低反应者的LDL-C和HDL-C没有增加，而高反应者的两种脂蛋白均升高。然而，冠心病风险的一个重要参数LDL/HDL比值在鸡蛋期对所有受试者均保持稳定，与反应无关。此外在此期间，高反应者的载脂蛋白C-III（p < 0.001）、载脂蛋白B（p < 0.001）和胆固醇酯转运蛋白（CETP）（p < 0.05）浓度更高。
这些数据表明，无论反应分类如何，过量膳食胆固醇不会增加绝经前女性发生致动脉粥样硬化脂蛋白谱的风险。虽然饮食中添加640毫克胆固醇确实导致高反应者血浆胆固醇升高，但LDL/HDL比值保持稳定。这一结果，伴随着CETP活性的增加，引发了一种推测，即高反应者可能通过增强逆向胆固醇转运途径来处理血浆中的过量胆固醇。随着这一机制的确定，需要进一步测量其他参数以验证这一结论。
