世界卫生组织建议无糖甜味剂不该用于体重控制

世界卫生组织 WHO 前阵子发布了 “Use of Non-Sugar Sweeteners: WHO Guideline”，指导建议人们使用无糖甜味剂（Non-Sugar Sweeteners，NSS）。无糖甜味剂就是我们常说的安赛蜜，阿斯巴甜等等。这些无糖甜味剂不被人体代谢或者无法提供能量，常见于一些饮料和零食里，我们常喝的零糖可乐就是放了这些东西代替了普通糖的甜味。

这个指导建议里有一条比较重要的推荐，WHO 建议无糖甜味剂 NSS 不应该被作为体重控制或者降低一些患非传染性疾病概率的手段。

WHO suggests that non-sugar sweeteners not be used as a means of achieving weight control or reducing the risk of noncommunicable diseases (conditional recommendation).

WHOUse of Non-Sugar Sweeteners: WHO Guideline

这个对于一些经常和零糖可乐的人来说是个比较重要的讯息。我们喝零糖可乐通常就是为了不让自己因为喝太多可乐发胖。在很多人的印象里，对于我们的健康来说，水优于零糖可乐，零糖可乐优于原味可乐。但是因为水不能给我们带来快乐，所以很多人都选择了零糖可乐。那么现在我们还该不该喝零糖可乐呢？我们来看一下 WHO 提供的一些支持该推荐的证据。

就成人实验及观测的证据，有两种，一种来自随机变量控制实验，另一种来自长期跟随观测走访调查。

随机变量控制实验

• NSS use in any manner resulted in reduced sugars and energy intake, lower body weight and lower BMI in short-term RCTs (all low certainty evidence), the majority of which lasted 3 months or less. NSS use did not significantly affect other measures of body fatness or intermediate markers of cardiometabolic health, including glucose, insulin or blood lipids (very low to moderate certainty evidence). Evidence from a small number of longer-term trials lasting 6–18 months did not suggest an effect on body weight but was difficult to interpret because of many differences in how these trials were conducted and results reported.
  这是一些可信度非常低的证据。基于所有 NSS 使用者的数据，无论 NSS 是以何种方式摄入，NSS 的使用会导致短期内的体重降低，但是观测不到其对其他肥胖指标的影响。而且就长期来看，NSS 对体重也没有影响。

• When intake of NSS was directly compared with intake of free sugars (i.e. one group in a trial received NSS, and another group received free sugars), those receiving NSS had lower body weight and BMI, similar in magnitude to the results when NSS was used in any manner. However, most of these trials provided foods and beverages containing NSS or free sugars in addition to existing diets and therefore did not directly measure the effects of replacing free sugars with NSS. When NSS were compared with nothing/placebo or water (i.e. one group in a trial received NSS, and another group received nothing/placebo or water), no effects on body weight or BMI were observed.
  当测试者分成两组（当然测试者不应该知道自己是哪一组的），一组使用 NSS，一组使用普通糖分添加剂，但两组平时的饮食还是保持正常，NSS 组使用者的体重更低。此外，另外还有一对照组使用安慰剂/水，当 NSS 组和该对照组比较时，NSS 并没有体现出减少体重的效果。这个实验结果不是可以预期的吗？

• When NSS were assessed specifically as replacements for free sugars in a small number of RCTs (i.e. habitual consumers of foods or beverages containing free sugars were asked to switch to versions containing NSS in place of free sugars), the effect on body weight was significantly weakened relative to that observed for NSS used in any manner, and an effect on BMI was no longer observed.
  比较有意思的是，当让习惯普通糖分添加剂饮食摄入的人改成 NSS 饮食摄入，我猜可能是让那些平时只喝原味可口可乐的人全部改换喝无糖可口可乐，NSS 对降低体重的效果很难展示出来。这大概意思就是说你想减肥的话，不是说把有糖饮料换成无糖饮料就能掉体重了。

长期跟随观测走访调查

• Higher intakes of NSS were associated with higher BMI and increased risk of incident obesity, but not other measures of body fatness (very low to low certainty evidence).
  NSS 的摄入量和体重，急性肥胖的风险呈正相关，且和其他肥胖指标不相关，尽管证据可信度非常低。

• Higher intakes of NSS were associated with increased risk of type 2 diabetes, CVDs and CVD mortality, and all-cause mortality in long-term prospective observational studies with average follow-up of 13 years (very low to low certainty evidence), but were not associated with differences in overall cancer incidence or mortality (very low certainty evidence).
  NSS 的摄入量和 II 型糖尿病，心血管疾病，心血管疾病死亡率，人整体死亡率呈正相关，和整体癌症率和癌症死亡率不相关，尽管证据可信度非常低。

• Use of NSS (predominantly saccharin) was associated with increased risk of bladder cancer as assessed in case–control studies (very low certainty evidence).
  NSS 的使用和膀胱癌有正相关，尽管证据可信度非常低。

总的来说，WHO 呈递的证据可信度都非常低，我如果是可乐生产商的话，出于自己的利益，那肯定也会出来反对的。但是 WHO 似乎是在给我们传递一个信息，零糖可乐对减肥没啥特别帮助。如果你想要减肥和绝对的健康，还是放弃快乐，运动和喝水吧。就我个人而言，我是不会放弃喝零糖可乐的，但可能会控制摄入量吧，之前喝的真的是挺多的。