植物胆固醇因添加到人造奶油、色拉调味汁及其它油类食品中能够降低胆固醇含量而受到重视，而且发现当植物胆固醇添加到橙汁中还可以降低低密度脂蛋白（LDL）或称“坏”胆固醇水平。日前，UC Davis的研究人员发现每天饮用添加植物甾醇的低热量橙汁也会降低C-反应蛋白（CRP）水平，而CRP为炎症标记物及公认的心血管病危险标记物。
“这是首次研究发现饮用含植物甾醇的橙汁能够降低CRP水平，”该研究的第一作者Sridevi Devaraj说。Devaraj是UC Davis实验室专门负责动脉粥样硬化及代谢病研究的研究人员，而且是一名病理学助教授。“我们已经认识到添加了植物甾醇的橙汁能够降低‘坏’蛋白水平。目前我们还研究发现它的其它作用，即有益于减少炎症，而炎症在心脏病进展中起关键作用。”Devaraj说。
基于72名健康志愿受试者8周的研究结果发表在《美国临床营养杂志》10月刊上。2004年，Devaraj同UC Davis医学病理学教授Ishwarlal Jialal首次验证饮用添加了植物甾醇的脱脂饮料能够降低人体内的胆固醇含量。当前研究进一步支持利用植物甾醇促进健康的理论。
“抵抗心脏病的最好办法是饮食及运动方式的改变。但现实是人们很难改变他们固有的习惯，”当前研究的联合作者Jialal解释说。“饮用添加植物甾醇的橙汁是一个相对简单的方法，也许会起到显著的预防作用。”
为了帮助人们减少患心脏病的风险，美国心脏协会与国家胆固醇教育机构联合推荐低饱和脂肪和胆固醇高溶解纤维及植物甾醇的饮食。含植物甾醇的食物数量很少，仅在水果、蔬菜、坚果、种子、谷类及豆类中存在。同胆固醇化学性质类似，植物甾醇被认为是通过限制胆固醇在肠中吸收而降低体内LDL水平。该研究中，72名健康男性志愿受试者继续他们的正常饮食，但在早餐和午餐时饮用一杯橙汁饮料。半数受试者饮用添加植物甾醇低热量的橙汁，而另一半受试者饮用不添加植物甾醇的橙汁。两种橙汁均由可口可乐公司卫生健康饮料协会提供。实验前及实验后均在禁食条件下采集血样进行分析，检测胆固醇水平。研究者发现饮用添加植物甾醇橙汁的志愿受试者LDL胆固醇水平平均下降9%，C-反应蛋白水平平均下降12%。而那些未饮用添加植物甾醇橙汁的志愿受试者LDL及CRP水平并无明显改变。
尽管预防和治疗取得了显著进展，但心血管疾病在西方国家仍是死亡的首要原因。几乎一半患有心血管疾病的人群血浆胆固醇及血脂水平并无升高。因此，近年来，炎症在心血管病进展中的作用的研究如火如荼。
最初研究报道认为CRP水平仅仅反映潜在的炎症进展。但，积累的数据表明 CRP也是一个诱发因素，越来越多的数据表明CRP水平的下降将使一些人受益。比如，CRP在动脉粥样硬化损伤中出现，一些研究表明CRP可能是动脉粥样硬化斑块不稳定及进展的促发因子。美国心脏病协会及疾病预防控制中心建议CRP可以用来评估心血管疾病风险。
Jialal认为，LDL胆固醇及CRP水平同步下降，同上述两者单独降低相比，能够预防更多的心脏病事件。 Devaraj指出，除了心血管疾病，在那些易患代谢综合症及糖尿病的人群中也发现了CRP水平升高。
“我们正处于‘富贵病’流行的时代。我们需要新的治疗策略帮助病人抵抗各种‘富贵病’，”Devaraj说。“饮用添加植物甾醇，特别是低热量的饮料，提供给病人一种简便易行的降低这些致死性疾病风险的方法。”
美国食品和药品监督管理部门总结认为，每份食物中含有至少0.4g的植物甾醇，每天食用两份这样的食物，总摄入0.8g的植物甾醇，能够降低饮食中的饱和脂肪及胆固醇含量，进而可能降低心血管疾病风险。
Orange juice beverage fortified with plant sterols lowers indicators of heart disease risk
'Bad' cholesterol and inflammation lowered in healthy volunteers
(SACRAMENTO, Calif.) -- Plant cholesterols known as sterols -- recognized for their cholesterol-lowering power when added to margarines, salad dressings and other fats -- also have been found to be effective in reducing low-density lipoprotein, or "bad" cholesterol" levels, when added to orange juice. Now, UC Davis researchers have found that twice-daily servings of a reduced-calorie orange juice beverage fortified with plant sterols also reduces levels of C-reactive protein, a marker of inflammation and an accepted risk marker for heart disease.
"This is the first study to show that healthy people who drink a plant sterol-fortified orange juice beverage can reduce C-reactive protein levels," said Sridevi Devaraj, lead author of the study. Devaraj is an associate professor of pathology and an investigator in the UC Davis Laboratory for Atherosclerosis and Metabolic Research. "We already knew that adding plant sterols to a juice could lower 'bad' cholesterol levels. Now we see an added benefit of reducing inflammation, a process we know plays an important role in the development of heart disease," Devaraj said.
The current results, based on an eight-week study of 72 healthy volunteers, appear in the October issue of the American Journal of Clinical Nutrition.
Devaraj and Ishwarlal Jialal, UC Davis professor of medicine and pathology, first showed the cholesterol-reducing effects of adding plant sterols to a nonfat beverage in 2004. The current findings further support the idea of using plant sterols to improve health.
"The best way to fight heart disease is through changes in diet and exercise. But, the reality is that people have trouble making those changes," explained Jialal, who is co-author on the current study. "Drinking a plant sterol-fortified orange juice beverage is a relatively simple thing to do and it may have important preventative effects."
To help individuals reduce their risk of heart disease, both the American Heart Association and the National Cholesterol Education Program recommend a diet low in saturated fat and cholesterol and high in soluble fiber and plant sterols. Sterols are present in small quantities in a variety of foods, including fruits, vegetables, nuts, seeds, cereals and legumes. Chemically similar to cholesterol, sterols are thought to lower LDL levels in the body by limiting absorption of cholesterol in the intestine.
In the current study, 72 healthy male volunteers ate their normal diet, but added a cup of the juice beverage to their breakfast and dinner. Half of the group drank a reduced-calorie, sterol-fortified orange juice beverage, while the other half drank a juice beverage without sterols. Both beverages were provided by The Coca-Cola Company's Beverage Institute for Health & Wellness.
Blood samples from fasting participants were taken before and after the trial to determine cholesterol levels. Researchers found that volunteers who drank the sterol-fortified orange juice beverage had an average 9-percent decrease in LDL cholesterol, and an average of 12-percent decrease in C-reactive protein levels. Researchers found no significant changes in LDL or C-reactive protein levels in those who drank the non-sterol fortified orange juice beverage.
Despite great strides in prevention and treatment, cardiovascular disease remains the leading cause of death throughout the Western world. Nearly half of all cardiovascular disease events occur in people without elevated blood cholesterol or lipid levels. Therefore, the potential role of inflammation in the development of cardiovascular disease has come under intense study in recent years.
Initial reports suggested C-reactive protein levels merely reflected an underlying inflammatory process. However, accumulating evidence now suggests that C-reactive protein could also be a causative factor, and there is growing circumstantial evidence that reducing C-reactive protein levels might benefit some individuals. For example, C-reactive protein is present in atherosclerotic lesions, and some studies suggest it may actively contribute to the progression and/or instability of atherosclerotic plaques. The American Heart Association and Centers for Disease Control and Prevention now recommend that C-reactive protein levels be used to further evaluate cardiovascular disease risk.
According to Jialal, the simultaneous reduction of LDL cholesterol and C-reactive protein levels prevents more heart attacks than reducing either measure alone. Devaraj pointed out that, in addition to cardiovascular disease, elevated levels of C-reactive protein have been found in those at risk of developing metabolic syndrome and diabetes.
"We are facing an epidemic of these lifestyle diseases. We need new strategies to help people fight back," Devaraj said. "Sterol-fortified, especially reduced-calorie beverages, offer our patients an effective, easy way to lower their risk of developing these deadly diseases."
The U.S. Food and Drug Administration has concluded that foods containing at least 0.4 grams per serving of plant sterols, consumed twice a day with meals for a daily total intake of at least 0.8 grams, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.
编辑：蓝色幻想
