Obesity and type 2 diabetes are major health problems affecting hundreds of millions of people. Caloric overfeeding with calorie-dense food ingredients like sugars may contribute to these chronic diseases. Sugar research has also identified mechanisms via which conventional sugars like sucrose and fructose can adversely influence metabolic health. To replace these sugars, numerous sugar replacers including artificial sweeteners and sugar alcohols have been developed. Rare sugars became new candidates to replace conventional sugars and their health effects are already reported in individual studies, but overviews and critical appraisals of their health effects are missing. This is the first paper to provide a detailed review of the metabolic health effects of rare sugars as a group. Especially allulose has a wide range of health effects. Tagatose and isomaltulose have several health effects as well, while other rare sugars mainly provide health benefits in mechanistic studies. Hardly any health claims have been approved for rare sugars due to a lack of evidence from human trials. Human trials with direct measures for disease risk factors are needed to allow a final appraisal of promising rare sugars. Mechanistic cell culture studies and animal models are required to enlarge our knowledge on understudied rare sugars.

肥胖和 2 型糖尿病是影响数亿人的主要健康问题。用高热量食物成分（如糖）摄入过多热量可能会导致这些慢性疾病。糖研究还确定了蔗糖和果糖等常规糖对代谢健康产生不利影响的机制。为了替代这些糖，已经开发了许多糖替代品，包括人造甜味剂和糖醇。稀有糖成为替代传统糖的新候选者，其健康影响已在个别研究中得到报道，但缺乏对其健康影响的概述和批判性评估。这是第一篇详细回顾稀有糖类对代谢健康影响的论文。尤其是阿洛酮糖具有广泛的健康影响。塔格糖和异麦芽酮糖也有多种健康影响，而其他稀有糖主要在机械研究中提供健康益处。由于缺乏人体试验的证据，几乎没有任何健康声明被批准用于稀有糖。需要对疾病风险因素进行直接测量的人体试验，以便最终评估有希望的稀有糖。需要机械细胞培养研究和动物模型来扩大我们对未充分研究的稀有糖的了解。