Throughout history, the only way humans could raise their blood ketone levels was by several days of fasting or by following a strict low-carb, high-fat diet. A recently developed, dietary source of ketones, a ketone monoester, elevates d-β-hydroxybutyrate (βHB) to similar concentrations within minutes, with βHB remaining raised for several hours. To date, the longest human safety study of the exogenous ketone ester was for 5 days, but longer consumption times may be desired. Here we report results for 24 healthy adults, aged 18-70 years, who drank 25 ml (26.8 g) of the ketone monoester, (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, three times a day for 28 days (a total of 2.1 L). Anthropomorphic measurements, plus fasting blood and urine analyses were made weekly. It was found that elevating blood βHB concentrations from 0.1 to 4.1 (±1.1) mM three times a day for 28 days had no effect on body weights or composition, fasting blood glucose, cholesterol, triglyceride or electrolyte concentrations, nor blood gases or kidney function, which were invariably normal. Mild nausea was reported following 6 of the 2,016 drinks consumed. We conclude that sustained exogenous ketosis using a ketone monoester is safe and well-tolerated by healthy adults.

中文翻译：

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在健康成年人中使用酮单酯饮料持续28天的持续性外源性酮症的安全性和耐受性。

纵观整个历史，人类提高其血酮水平的唯一方法是禁食几天或遵循严格的低碳水化合物，高脂肪饮食。最近开发的饮食中的酮（酮单酯）来源可在数分钟内将d-β-羟基丁酸酯（βHB）升高至相似的浓度，而βHB则保持升高数小时的状态。迄今为止，对外源酮酯的最长人类安全性研究为5天，但可能需要更长的食用时间。在这里，我们报告了24位年龄在18-70岁的健康成年人的结果，这些成年人每天喝25毫升（26.8克）酮单酯（R）-3-羟基丁基（R）-3-羟基丁酸酯，共28天（共2.1公升）。每周进行拟人化测量以及空腹血液和尿液分析。发现将血液中的βHB浓度从0.1提高到4.1（±1。1）每天三次，连续28天，每天三次，对体重或组成，空腹血糖，胆固醇，甘油三酸酯或电解质浓度没有影响，也没有血气或肾功能的影响，这些都是正常的。在所喝的2,016杯饮品中，有6杯被报告有轻微的恶心。我们得出结论，使用健康的成年人，使用酮类单酯持续外源性酮症是安全且耐受性良好的。