两篇《柳叶刀》论文:颠覆你对脂肪和碳水化合物的传统看法,或需修改《膳食指南》
2017/09/02
传统上,我们一般认为应该吃低脂肪的食物会有利于身体健康, 但是近日发表在国际著名医学期刊《柳叶刀》上的两篇论文结果却让人们跌破眼球,颠覆了我们对脂肪和碳水化合物的看法。它不仅给“脂肪”正了名,还质疑了蔬菜和水果是不是吃“越多越好”。

当你看到食物中充满脂肪,是不是觉得这是个很“肮脏”的字眼。第一反应就是吃了这个又要发胖几斤?然后就是发胖后各种不好的想象?的确,肥胖让人心力憔悴,但饮食中的“脂肪”并非罪魁祸首。

近期发表在国际著名医学期刊《柳叶刀》上的两篇文章,不仅给“脂肪”正了名,还质疑了蔬菜和水果是不是吃“越多越好”。有意思的是,这两篇文章都是来自于同一大型研究。


这项叫PURE (Perspective Urban Rural Epidemiology)的大型研究包含了来自18个包括高收入、中等收入和低收入国家和地区(北美、欧洲、南美、中东、南亚、中国、东南亚以及非洲的613个社区)的超过135335人,平均年龄在35岁到70岁之间,入组时间为2003年1月1日至2013年3月31日,并对他们的饮食习惯和健康状况进行了平均七年以上的的随访记录。

结果发现,脂肪摄入最多的人群——脂肪摄入占饮食总热量的35%,在研究期间的死亡率比吃脂肪较少的人(脂肪摄入占总热量的10%)低23%。而各种心血管疾病的发病率基本相当,甚至吃脂肪多的人群中风几率还更小。

而更令人意外的结果是,碳水化合物摄入最多的人群——占总热量的77%,比吃碳水化合物少的人(占总热量的46%)死亡率高28%。

据悉,这两大惊人结果不仅发表在《柳叶刀》杂志上,还在近日欧洲心脏病学会巴塞罗那会议上被公布。

哈佛公共卫生学院流行病学与营养学T.H. Chan学院Eric Rimm博士表示,这些研究结果指出,人类的生物在全球范围内是非常相似的;无论住在哪里,吃高加工的碳水化合物都是不健康的。

研究一:Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study(来自五大洲18个国家的脂肪和碳水化合物摄入量与心血管疾病和死亡率关联的一项前瞻性队列研究)


在7.4年的中位随访时间内,研究人员共统计到了5796例死亡和4784例心血管疾病。结果显示:

营养素估计百分比能量与总死亡率和主要心血管疾病之间的关系(N=135335)

根据年龄、性别、教育程度、腰臀比、吸烟、体力活动、糖尿病、城市或乡村位置、中心、地理区域和能量摄入等因素进行调整。

主要心血管疾病风险=致命性心血管疾病+心肌梗死+中风+心力衰竭

1. 更高的碳水化合物摄入和更高的总死亡率风险相关:相比于等级1(摄入最少)的碳水化合物摄入,等级5的HR(hazard ratio,风险比)=1.28(95%置信区间1.12–1.46),趋势p=0.0001。更高的碳水化合物摄入和心血管疾病、心血管死亡率风险的关联不显著。

2. 无论是总脂肪、还是任一类型脂肪(饱和脂肪、不饱和脂肪)的摄入,都和更低的总死亡率风险相关。相比于等级1,摄入量为第5等级的HR分别为:总脂肪HR=0.77(0.67–0.87),趋势p<0.0001;饱和脂肪,HR=0.86(0.76–0.99),趋势p=0.0088;单不饱和脂肪,HR=0.81(0.71–0.92),趋势p<0.0001;多不饱和脂肪,HR=0.80(0.71–0.89),趋势p<0.0001。

3. 更高的饱和脂肪摄入和更低的卒中发生风险相关:相比于等级1的饱和脂肪摄入,等级5的HR=0.79(0.64–0.98),趋势p=0.0498。总脂肪、饱和脂肪以及不饱和脂肪摄入和心肌梗死或心血管死亡率的关联不显著。

4. 总蛋白摄入与总死亡率(HR=0.88,95%置信区间0.77-1.00;趋势p=0.0030)和非心血管疾病死亡率(HR=0.85,95%置信区间0.73-1.99;趋势p=0.0022)的风险负相关。动物蛋白摄入与更低的总死亡率风险相关,但植物蛋白和总死亡率风险间未发现显著相关。

5.与最低脂肪摄入组(10.6%)相比,最高摄入组(35.3%)全因死亡风险、中风和非心血管死亡风险都更低,下降程度从18-30%不等;而且在心血管疾病的发病和死亡风险这项上,脂肪摄入量与它并不存在明显相关。同样的结论还可以推到饱和脂肪酸上,摄入量较高(10-13%)的人心血管疾病的发生和死亡风险也均未受到影响,全因死亡风险和中风风险也下降了。

这说明:饮食当中的脂肪的摄入和各种脂肪亚型的摄入都与较低的总体死亡率有关系。总脂肪和各种脂肪亚类实际上与较低的死亡率相关联。这些脂肪并不会导致增加的心血管疾病、心肌梗塞的发生及心血管疾病的死亡率。相反,饱和脂肪酸反而会降低中风的危险性。

因此考虑到这种情况,全球的膳食指南或需做出相应的修改。

研究二:Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study(18个国家的水果、蔬菜和豆类摄入量以及心血管疾病和死亡的一项前瞻性队列研究)


这项研究调整了年龄、性别、研究中心的模型中,更高的水果、蔬菜、豆类总摄入量与主要心血管疾病、心肌梗死、心血管死亡率、非心血管死亡率、总死亡率之间呈负相关。

在调整了其他潜在的饮食和非饮食混杂因素后,效应明显削弱:主要心血管疾病的HR为0.90(0.74–1.10), 趋势p=0.1301;心肌梗死HR为0.99(0.74–1.31),趋势p=0.2033;卒中HR为0.92(0.67–1.25),趋势p=0·7092;心血管死亡率HR为0.73(0.53–1.02),趋势p=0.0568;非心血管死亡率HR为0.84(0.68–1.04),趋势p=0.0038;总死亡率HR为0.81(0.68–0.96), 趋势p<0.0001。

相比参照组,每天摄入3-4份水果、蔬菜、豆类(相当于375-500g/d)的总死亡率HR最低(0.78,95%置信区间0.69–0.88),超过这个量,HR没有出现进一步的显著降低。

单独来看,水果摄入与更低的心血管、非心血管和总的死亡率风险相关,豆类摄入与非心血管死亡和总死亡率呈负相关(完全调整模型中)。生蔬菜摄入与更低的总死亡率风险有强相关,而经过烹饪的蔬菜,效应会有所削弱。即饮食当中摄入较多的碳水化合物会引起较高的总体死亡率

这说明:摄入更多的水果、蔬菜、豆类,与更低的非心血管死亡率和总死亡率风险有相关性。每天摄入3-4份(相当于375-500g/天),能最大程度地降低非心血管死亡率及总死亡率。

弗里德曼营养科学与政策学院(Tufts Friedman School of Nutrition Science and Policy)院长Dariush Mozaffarian说:“减少淀粉和糖,从植物中增加更多的脂肪和食物,尤其是有活性的水果和种子,值得我们去实践”。

参考资料:

Huge new study casts doubt on conventional wisdom about fat and carbs

Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study

Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study

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  • Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study

    Background The relationship between macronutrients and cardiovascular disease and mortality is controversial. Most available data are from European and North American populations where nutrition excess is more likely, so their applicability to other populations is unclear. Methods The Prospective Urban Rural Epidemiology (PURE) study is a large, epidemiological cohort study of individuals aged 35–70 years (enrolled between Jan 1, 2003, and March 31, 2013) in 18 countries with a median follow-up of 7·4 years (IQR 5·3–9·3). Dietary intake of 135 335 individuals was recorded using validated food frequency questionnaires. The primary outcomes were total mortality and major cardiovascular events (fatal cardiovascular disease, non-fatal myocardial infarction, stroke, and heart failure). Secondary outcomes were all myocardial infarctions, stroke, cardiovascular disease mortality, and non-cardiovascular disease mortality. Participants were categorised into quintiles of nutrient intake (carbohydrate, fats, and protein) based on percentage of energy provided by nutrients. We assessed the associations between consumption of carbohydrate, total fat, and each type of fat with cardiovascular disease and total mortality. We calculated hazard ratios (HRs) using a multivariable Cox frailty model with random intercepts to account for centre clustering. Findings During follow-up, we documented 5796 deaths and 4784 major cardiovascular disease events. Higher carbohydrate intake was associated with an increased risk of total mortality (highest [quintile 5] vs lowest quintile [quintile 1] category, HR 1·28 [95% CI 1·12–1·46], ptrend=0·0001) but not with the risk of cardiovascular disease or cardiovascular disease mortality. Intake of total fat and each type of fat was associated with lower risk of total mortality (quintile 5 vs quintile 1, total fat: HR 0·77 [95% CI 0·67–0·87], ptrend<0·0001; saturated fat, HR 0·86 [0·76–0·99], ptrend=0·0088; monounsaturated fat: HR 0·81 [0·71–0·92], ptrend<0·0001; and polyunsaturated fat: HR 0·80 [0·71–0·89], ptrend<0·0001). Higher saturated fat intake was associated with lower risk of stroke (quintile 5 vs quintile 1, HR 0·79 [95% CI 0·64–0·98], ptrend=0·0498). Total fat and saturated and unsaturated fats were not significantly associated with risk of myocardial infarction or cardiovascular disease mortality. Interpretation High carbohydrate intake was associated with higher risk of total mortality, whereas total fat and individual types of fat were related to lower total mortality. Total fat and types of fat were not associated with cardiovascular disease, myocardial infarction, or cardiovascular disease mortality, whereas saturated fat had an inverse association with stroke. Global dietary guidelines should be reconsidered in light of these findings.

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  • Fruit, vegetable, and legume intake, and cardiovascular disease and deaths in 18 countries (PURE): a prospective cohort study

    Background The association between intake of fruits, vegetables, and legumes with cardiovascular disease and deaths has been investigated extensively in Europe, the USA, Japan, and China, but little or no data are available from the Middle East, South America, Africa, or south Asia. Methods We did a prospective cohort study (Prospective Urban Rural Epidemiology [PURE] in 135 335 individuals aged 35 to 70 years without cardiovascular disease from 613 communities in 18 low-income, middle-income, and high-income countries in seven geographical regions: North America and Europe, South America, the Middle East, south Asia, China, southeast Asia, and Africa. We documented their diet using country-specific food frequency questionnaires at baseline. Standardised questionnaires were used to collect information about demographic factors, socioeconomic status (education, income, and employment), lifestyle (smoking, physical activity, and alcohol intake), health history and medication use, and family history of cardiovascular disease. The follow-up period varied based on the date when recruitment began at each site or country. The main clinical outcomes were major cardiovascular disease (defined as death from cardiovascular causes and non-fatal myocardial infarction, stroke, and heart failure), fatal and non-fatal myocardial infarction, fatal and non-fatal strokes, cardiovascular mortality, non-cardiovascular mortality, and total mortality. Cox frailty models with random effects were used to assess associations between fruit, vegetable, and legume consumption with risk of cardiovascular disease events and mortality. Findings Participants were enrolled into the study between Jan 1, 2003, and March 31, 2013. For the current analysis, we included all unrefuted outcome events in the PURE study database through March 31, 2017. Overall, combined mean fruit, vegetable and legume intake was 3·91 (SD 2·77) servings per day. During a median 7·4 years (5·5–9·3) of follow-up, 4784 major cardiovascular disease events, 1649 cardiovascular deaths, and 5796 total deaths were documented. Higher total fruit, vegetable, and legume intake was inversely associated with major cardiovascular disease, myocardial infarction, cardiovascular mortality, non-cardiovascular mortality, and total mortality in the models adjusted for age, sex, and centre (random effect). The estimates were substantially attenuated in the multivariable adjusted models for major cardiovascular disease (hazard ratio [HR] 0·90, 95% CI 0·74–1·10, ptrend=0·1301), myocardial infarction (0·99, 0·74–1·31; ptrend=0·2033), stroke (0·92, 0·67–1·25; ptrend=0·7092), cardiovascular mortality (0·73, 0·53–1·02; ptrend=0·0568), non-cardiovascular mortality (0·84, 0·68–1·04; ptrend =0·0038), and total mortality (0·81, 0·68–0·96; ptrend<0·0001). The HR for total mortality was lowest for three to four servings per day (0·78, 95% CI 0·69–0·88) compared with the reference group, with no further apparent decrease in HR with higher consumption. When examined separately, fruit intake was associated with lower risk of cardiovascular, non-cardiovascular, and total mortality, while legume intake was inversely associated with non-cardiovascular death and total mortality (in fully adjusted models). For vegetables, raw vegetable intake was strongly associated with a lower risk of total mortality, whereas cooked vegetable intake showed a modest benefit against mortality. Interpretation Higher fruit, vegetable, and legume consumption was associated with a lower risk of non-cardiovascular, and total mortality. Benefits appear to be maximum for both non-cardiovascular mortality and total mortality at three to four servings per day (equivalent to 375–500 g/day).

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