20多年来各国营养指导都推荐多吃非饱和脂肪，如橄榄油、玉米油等植物油。建议避免饱和脂肪，如黄油、肥肉、香肠、熏肉、奶酪等......但剑桥大学今日(3/18/2014)发表在内科年刊的一篇荟萃分析，发现前者并没有起到保护作用，和后者的风险一样。 植物油如色拉油也不能提供所谓的健康保护作用。只要是脂肪，过多摄入对健康都同样有害，无论是饱和还是不饱和。
当然，文里也谨慎地加了一Limitation。
Limitation: Potential biases from preferential publication and selective reporting.
Conclusion: Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats.
哈哈，今天下班我顺便买了一大桶全脂奶。儿子说太好喝了，回到他一周岁时的岁月啦~.~ 我也喝了一杯，嗯，真的和吃lindt chocolate一样地享受。小女儿不为所动，继续用non-fat milk打她的smoothie和做她明天要带去学校的cookies。
内科年刊链接: http://annals.org/article.aspx?articleid=1846638
以上的内科年刊的全文要注册才能看到，贴一下Medscape的链接: http://www.medscape.com/viewarticle/822092
摘录一些数据:
As for the analysis itself, it covered 45 prospective observational studies and 27 randomized controlled trials looking at dietary PUFA intake, levels of circulating PUFA, and intake of fatty-acid dietary supplements in populations throughout the most of the world.
Relative Risk (95% CI) for Coronary Events, Top vs Bottom Third of Total Dietary Fatty-Acid Intake Levels in Prospective Cohort Studies*
| Fatty-Acid Type | RR (95% CI) |
| Saturated | 1.02 (0.97–1.07) |
| Monosaturated | 0.99 (0.89–1.09) |
| Long-chain omega-3 | 0.93 (0.84–1.02) |
| Omega-6 | 1.01 (0.96–1.07) |
| Trans | 1.16 (1.06–1.27) |
*32 studies, 530 525 participants, mean follow-up 5–23 years. All adjusted for age, sex, smoking, diabetes, and blood pressure, and other influences on CV risk
"Among studies with available data," the group writes, "there were moderate positive correlations between dietary intake and circulating composition of total omega-3 and omega-6 polyunsaturated fatty acids and weak positive correlations for total saturated and monounsaturated fatty acids."
Relative Risk (95% CI) for Coronary Events, Top vs Bottom Third of Circulating Fatty-Acid Levels in Prospective Cohort Studies*
| Fatty-Acid Type | RR (95% CI) |
| Saturated | 1.06 (0.86–1.30) |
| Monosaturated | 1.06 (0.97–1.17) |
| Long-chain omega-3 | 0.84 (0.63–1.11) |
| Omega-6 | 0.94 (0.84–1.06) |
| Trans | 1.05 (0.76–1.44) |
*19 studies, 32 307 participants, mean follow-up 1.3–30.7 years
Also, there was evidence that "circulating levels of eicosapentaenoic and docosahexaenoic acids . . . and arachidonic acid are each associated with lower coronary risk."
Consistent with the literature and guidelines, total dietary trans-fatty-acid intake was positively associated with coronary disease risk.
Relative Risk (95% CI) for Coronary Events in Randomized Trials, Fatty-Acid Dietary Supplements vs Control Group*
| Parameter | RR (95% CI) |
| Alpha linolenic | 0.97 (0.69–1.36) |
| Long-chain omega-3 | 0.94 (0.86–1.03) |
| Omega-6 | 0.89 (0.71–1.12) |
*27 trials, 103 052 participants, mean follow-up 0.1–8 years
Di Angelantonio pointed out that his group's analysis is not the first to question the evidence base for an adverse effect of dietary saturated fat on cardiovascular health.
