前情提要
這對(duì)吃貨們而言絕對(duì)是一個(gè)好消息，愛(ài)爾蘭《乳制食品攝入形式、身體成分與代謝健康指標(biāo)：全國(guó)成人營(yíng)養(yǎng)調(diào)查結(jié)果》為那些愛(ài)吃乳制品的人帶來(lái)了福音。人們之前一直認(rèn)為諸如黃油、奶油、奶酪、全脂牛奶這些高脂肪乳制品的飽和脂肪含量很高，如果想要保持健康，只能偶爾吃一次。但是，該研究的結(jié)果恰恰與人們的想法相反。
2017年2月20日，英國(guó)《自然》旗下《營(yíng)養(yǎng)學(xué)與糖尿病》在線發(fā)表都柏林大學(xué)學(xué)院、科克大學(xué)學(xué)院的愛(ài)爾蘭全國(guó)成人營(yíng)養(yǎng)調(diào)查研究報(bào)告，發(fā)現(xiàn)乳制品攝入量較多，體內(nèi)脂肪含量和體重指數(shù)反而較低，黃油、奶油、奶酪、全脂牛奶也未必使甘油三酯或膽固醇升高。
血液低密度脂蛋白膽固醇水平高可能增加心臟病的風(fēng)險(xiǎn)，每年大約有一萬(wàn)名愛(ài)爾蘭人死于心臟病，與世界上的心臟病死亡率基本相同。該研究發(fā)現(xiàn)，奶酪和其他高脂肪乳制品可能并非罪魁禍?zhǔn)住?/p>
既往研究分析乳制品攝入量與代謝健康之間相關(guān)性的結(jié)果存在分歧，部分原因可能為：對(duì)乳制品的定義不同，或者僅僅孤立分析單一類(lèi)型乳制品。
本研究分析了乳制品食物攝入量與代謝健康之間的相關(guān)性，確定了乳制品食物攝入形式，并確定了乳制品飲食形式是否與代謝健康結(jié)局有相關(guān)性。
該研究入組1500位18～90歲生活自理的愛(ài)爾蘭健康成人，使用4天食物日記，記錄食物和飲料攝入的乳制品（定義為牛奶、奶酪、酸奶、奶油、黃油），收集空腹血樣897份，并進(jìn)行人體測(cè)量，通過(guò)協(xié)方差分析檢驗(yàn)乳制品攝入量三分位數(shù)及其形式的代謝健康指標(biāo)差異，使用歸類(lèi)分析確定不同脂肪含量乳制品攝入形式。
結(jié)果發(fā)現(xiàn)，根據(jù)性別、年齡、社會(huì)階層、吸煙程度、能量攝入進(jìn)行校正后，較高的乳制品總攝入量，與較低的體重指數(shù)、身體脂肪百分比、腰圍、腰臀比（P＜0.001）、收縮壓（P=0.02）、舒張壓（P＜0.001）有相關(guān)性。當(dāng)分別考慮牛奶和酸奶攝入量時(shí)，觀察到類(lèi)似趨勢(shì)。
而且，較高的奶酪攝入量，與反映胰島β細(xì)胞分泌功能的C肽水平較高（P＜0.001）有相關(guān)性。雖然酸奶攝入量最多者的血脂水平最低，但是與奶酪攝入量最多者相比，新陳代謝指標(biāo)無(wú)顯著差異。
此外，根據(jù)飲食形式分析，可以將乳制品攝入分為三種形式類(lèi)型：全脂牛奶、脫脂牛奶和酸奶、黃油和奶油。其中，脫脂牛奶和酸奶類(lèi)型的健康飲食指數(shù)評(píng)分最高、脂肪和飽和脂肪的攝入量較低，但是與甘油三酯（P=0.028）和總膽固醇（P=0.015）水平較高有相關(guān)性。常吃奶酪的人與不吃或吃較少奶酪的人相比，雖然飽和脂肪攝入較多，但是低密度脂蛋白膽固醇水平卻無(wú)顯著差異。
因此，這些結(jié)果表明，雖然攝入脫脂牛奶和酸奶有利于人體，但是作為低脂高碳水化合物飲食形式攝入時(shí)，對(duì)血脂譜較不利。
這到底是怎么回事？是愛(ài)爾蘭人僥幸，還是為了健康，我們也應(yīng)該開(kāi)始喝全脂牛奶、吃奶酪？
其實(shí)，相關(guān)性未必等于因果性，因此我們可能會(huì)發(fā)現(xiàn)那些攝入低脂肪食物者也可能攝入了一些引起膽固醇升高的食物。此外，研究者讓研究對(duì)象自己記錄飲食，可能無(wú)法證明記錄是否有遺漏或有偏差，而且食物日記也可能使人改變自己的飲食習(xí)慣。
營(yíng)養(yǎng)科學(xué)極其復(fù)雜，如同營(yíng)養(yǎng)學(xué)家至今無(wú)法確定禁食療法是否可行、無(wú)麩質(zhì)飲食是否增加糖尿病風(fēng)險(xiǎn)。因此，我們需要考慮的不僅僅是營(yíng)養(yǎng)素本身，還有我們攝入營(yíng)養(yǎng)素的形式，以及飲食的總體結(jié)構(gòu)，也就是說(shuō)，不僅需要考慮攝入的食物，還要考慮各種食物的搭配。
為此，需要開(kāi)展更多研究以更好地了解此相關(guān)性?，F(xiàn)在，這個(gè)問(wèn)題仍然懸而未決，營(yíng)養(yǎng)學(xué)家需要進(jìn)行更多研究、更長(zhǎng)時(shí)間、尋找更多元化人群，以弄清楚：當(dāng)我們享用吐司上的美式奶酪、英式干酪或稀奶油制成的新鮮軟質(zhì)奶酪時(shí)，體內(nèi)到底發(fā)生了什么？
不過(guò)，趁現(xiàn)在尚無(wú)定論，我們可以先拋開(kāi)內(nèi)疚，開(kāi)心地吃點(diǎn)奶酪、喝點(diǎn)全脂牛奶。
做人呢，最重要的就是開(kāi)心，祝大家周末愉快！
Nutr Diabetes. 2017 Feb 20;7(2):e243.
Patterns of dairy food intake, body composition and markers of metabolic health in Ireland: results from the National Adult Nutrition Survey.
Feeney EL, O'Sullivan A, Nugent AP, McNulty B, Walton J, Flynn A, Gibney ER.
University College Dublin, Dublin, Ireland; University College Cork, Cork, Ireland.
BACKGROUND: Studies examining the association between dairy consumption and metabolic health have shown mixed results. This may be due, in part, to the use of different definitions of dairy, and to single types of dairy foods examined in isolation.
OBJECTIVE: The objective of the study was to examine associations between dairy food intake and metabolic health, identify patterns of dairy food consumption and determine whether dairy dietary patterns are associated with outcomes of metabolic health, in a cross-sectional survey.
DESIGN: A 4-day food diary was used to assess food and beverage consumption, including dairy (defined as milk, cheese, yogurt, cream and butter) in free-living, healthy Irish adults aged 18-90 years (n=1500). Fasting blood samples (n=897) were collected, and anthropometric measurements taken. Differences in metabolic health markers across patterns and tertiles of dairy consumption were tested via analysis of covariance. Patterns of dairy food consumption, of different fat contents, were identified using cluster analysis.
RESULTS: Higher (total) dairy was associated with lower body mass index, %body fat, waist circumference and waist-to-hip ratio (P<0.001), and lower systolic (P=0.02) and diastolic (P<0.001) blood pressure. Similar trends were observed when milk and yogurt intakes were considered separately. Higher cheese consumption was associated with higher C-peptide (P<0.001). Dietary pattern analysis identified three patterns (clusters) of dairy consumption; 'Whole milk', 'Reduced fat milks and yogurt' and 'Butter and cream'. The 'Reduced fat milks and yogurt' cluster had the highest scores on a Healthy Eating Index, and lower-fat and saturated fat intakes, but greater triglyceride levels (P=0.028) and total cholesterol (P=0.015).
CONCLUSION: Overall, these results suggest that while milk and yogurt consumption is associated with a favourable body phenotype, the blood lipid profiles are less favourable when eaten as part of a low-fat high-carbohydrate dietary pattern. More research is needed to better understand this association.
CONCLUSION: Overall, these results suggest that although milk and yogurt consumption is associated with a favourable body phenotype, the blood lipid profiles are less favourable when eaten as part of a low-fat high-carbohydrate dietary pattern. More research is needed to better understand this association.
PMID: 28218736
DOI: 10.1038/nutd.2016.54
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