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营养学家建议胆固醇水平偏高者少吃或不吃动物脂肪。丹麦哥本哈根大学研究人员发现，并非所有含动物脂肪的食物都不好。同样由牛奶制成，奶酪不会影响人体内“坏胆固醇”水平，黄油则会。 对比饮食 研究人员征募大约50名志愿者，调整他们的饮食，记录由此带来的胆固醇水平变化等内容。 研究人员将志愿者随机分成两组，每天除规定热量食物外，让第一组食用奶酪，第二组食用黄油，摄取量占总热量的13%。6周后，连续两周正常进食。之后再次限制热量饮食，第一组改吃黄油，第二组食用奶酪，摄取量仍占总热量的13%，连续食用6周。 结果显示，与正常饮食期间相比，志愿者食用奶酪期间，体内俗称“坏胆固醇”的低密度脂蛋白水平和总胆固醇水平没有增长，食用黄油期间“坏胆固醇”水平增高7%。此外，食用奶酪期间，俗称“好胆固醇”的高密度脂蛋白比食用黄油期间略低。 分析原因 朱莉·耶普斯特德和同事在由最新一期《美国临床营养学期刊》（The American Journal of clinical nutrition）发表的报告中写道：“与黄油相比，奶酪降低‘坏胆固醇’水平；与正常饮食相比，奶酪并未增加‘坏胆固醇’水平。”“坏胆固醇”水平偏高容易造成动脉粥样硬化、心脏病和中风。 研究人员认为，奶酪对人体影响异于黄油可能有多个原因。不过，他们并未给出结论性解释。 原因之一可能在于奶酪富含钙。先前研究结果显示，钙能够促使脂肪经消化道排出体外。哥本哈根大学研究人员发现，志愿者食用奶酪时排泄的脂肪略多，不过数字不具统计学意义。 另一原因可能在于奶酪含有大量蛋白质，加工时需要发酵，这两点使得奶酪消化方式异于黄油。 建议适量 英国慈善机构“英国心脏”致力于宣传预防胆固醇水平偏高引发心脏病。该机构营养学家琳达·梅因告诉英国《每日邮报》记者，丹麦哥本哈根大学这项研究提供一些有趣发现，需要进一步研究。 “可能是奶酪中的其他营养成分，譬如乳蛋白多肽、钙或者其他微量元素，对血脂水平造成积极影响，”梅因说，“‘英国心脏’目前就食用奶酪的建议是，适量摄取，食用小份加味奶酪，选低脂奶酪取代高脂奶酪。”(生物谷 Bioon.com) Cheese intake in large amounts lowers LDL-cholesterol concentrations compared with butter intake of equal fat content Julie Hjerpsted, Eva Leedo, and Tine Tholstrup Background: Despite its high content of saturated fatty acids, cheese does not seem to increase plasma total and LDL-cholesterol concentrations when compared with an equivalent intake of fat from butter. This effect may be due to the high calcium content of cheese, which results in a higher excretion of fecal fat. Objectives: The objective was to compare the effects of diets of equal fat content rich in either hard cheese or butter or a habitual diet on blood pressure and fasting serum blood lipids, C-reactive protein, glucose, and insulin. We also examined whether fecal fat excretion differs with the consumption of cheese or butter. Design: The study was a randomized dietary intervention consisting of two 6-wk crossover periods and a 14-d run-in period during which the subjects consumed their habitual diet. The study included 49 men and women who replaced part of their habitual dietary fat intake with 13% of energy from cheese or butter. Results: After 6 wk, the cheese intervention resulted in lower serum total, LDL-, and HDL-cholesterol concentrations and higher glucose concentrations than did the butter intervention. Cheese intake did not increase serum total or LDL-cholesterol concentrations compared with the run-in period, during which total fat and saturated fat intakes were lower. Fecal fat excretion did not differ between the cheese and butter periods. Conclusion: Cheese lowers LDL cholesterol when compared with butter intake of equal fat content and does not increase LDL cholesterol compared with a habitual diet. This trial is registered at clinicaltrials.gov as NCT01140165. |
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