糖代用品的承诺很简单：从酸奶到牙膏都在使用它们，宣称可让人享受甜味而不增加体重，也避免糖引起的龋齿。它们是一个混合群体，包括合成成分（如阿斯巴甜、糖精和蔗糖素）和植物来源化合物，如赤藓糖醇、麦芽糖醇、山梨醇、木糖醇及甜菊糖，且部分产品甜度是蔗糖的数百倍，因此只需很小剂量添加。

一些研究认为它们在小剂量下几乎不影响代谢，因为使用量很低且有人认为主要以未改变状态排出。随机对照试验（通常为4到12周）显示，用这些甜味剂替代糖通常会降低体重增加，但大型长期观察研究却更常见相反结果：甜味剂摄入更高的人比摄入最少的人更容易增重。相同观察研究还把更高的糖代用品使用与更高的心脏病、糖尿病和癌症发生率联系到“完全不使用”者，尽管这类结果只能说明相关性而非因果。

因此，因果推断在此类研究中很难建立，因为高摄入者本身可能已处于更高风险状态；即便如此，世界卫生组织于2023年仍发布了预防性建议，反对把糖代用品当作减重或预防慢性病手段（但该建议不适用于糖尿病患者）。可能机制包括与糖激活相似的有害肠道和代谢信号、影响免疫细胞抗瘤功能，以及改变肠道菌群结构向不利菌群偏移；此外，许多食品和饮料会并用多种甜味剂（如预包装零食、碳酸饮料、能量饮料和蛋白饮料），因此更稳妥的做法是尽量避免这些产品，若想要甜味，选择常见水果更合适。

Sugar substitutes are marketed as a way to enjoy sweetness without weight gain or tooth decay, and they now appear in products ranging from yogurt to toothpaste. The category is mixed, combining synthetic compounds such as aspartame, saccharin, and sucralose with plant-derived compounds including erythritol, maltitol, sorbitol, xylitol, and stevia, and some are hundreds of times sweeter than sugar, so only tiny doses are needed.

Despite high-dose assumptions based on small use and reports of largely unchanged excretion, the evidence is mixed: randomized controlled trials of typically 4–12 weeks often report lower weight gain when sugar is replaced, while large long-term observational studies frequently show the opposite, with higher sweetener intake linked to more weight gain than among low users. The same observational literature also associates higher intake with elevated rates of cardiovascular disease, diabetes, and cancer versus abstainers, though these findings remain correlational.

Causality is difficult to prove because people who consume large amounts may already be at greater baseline risk, yet the WHO still issued 2023 precautionary guidance against using sweeteners for weight control or chronic-disease prevention (the advice does not apply to people with diabetes). Proposed mechanisms include shared harmful gut and metabolic signaling with sugar, potential immune effects on anti-tumor cell function, and gut microbiome shifts favoring harmful species, while manufacturers often combine multiple sweeteners in packaged snacks and carbonated, energy, and protein drinks, making practical avoidance difficult and supporting a cautious approach that favors fruit over processed sweetened products.

Source: Are sugar substitutes healthier than the real thing?

Subtitle: We share some bitter truths

Dateline: 4月 16, 2026 04:15 上午