A new “beverage hydration index” provides evidence-based suggestions for how to most efficiently hydrate. The index was developed from a British study published in December that tracked how long 13 common beverages remain in the body after being consumed.

“In the last 25 years, we’ve done many studies on rehydration after exercise,” said Ronald J. Maughan, a hydration expert from Loughborough University, and lead author of the study. “We thought it was time to look at hydration in typical consumers who aren’t exercising.”

The hydration index is modeled after the well-known glycemic index, which measures how the body responds to the carbohydrate content of different foods. The guiding principle behind the new hydration index is that some fluids last longer in your body than others, providing more hydration.

The British study determined the hydration index of 13 common beverages by having the participants, 72 males in their mid-20s, drink a liter of water as the standard beverage. The amount of water still remaining in subjects’ bodies two hours later was assigned a score of 1. All other beverages were evaluated in a similar manner, and then scored in comparison to water. A score higher than 1 indicated that more of the beverage remained in the body as compared to water, while a score lower than 1 indicated a higher excretion rate than water.

The results showed that four beverages — oral rehydration solution, like Pedialyte, fat-free milk, whole milk and orange juice — had a significantly higher hydration index than water. The first three had hydration index scores around 1.5, with orange juice doing slightly better than water at 1.1.

Why is milk so efficient at rehydration? Normally when you drink, it signals the kidneys to get rid of the extra water by producing more urine. However, when beverages contain nutrients and electrolytes like sodium and potassium, as milk does, the stomach empties more slowly with a less dramatic effect on the kidneys.

新出台的“饮品补水指数”为高效补水的方式提供了有证据的建议。这项指数基于2015年12月英国发布的一项研究，追踪记录了13种常见饮品在被摄取后停留人体的时间。

“在过去的25年中，我们针对运动后人们的补水状况进行了许多研究，”罗纳德•J•莫恩说道，他是拉夫堡大学的补水研究专家，同时也是这项研究的主要作者。“我们认为是时候研究不运动人群的补水状况了。”补水指数的设定参照了众所周知的血糖指数，血糖指数测量的是身体对不同食物中碳水化合物的反应。新的补水指数的指导原则是：某些液体在体内留存更久，因此具备更好的补水能力。毕竟，你若是饮下一杯八盎司的水，而后立即小解排出一半，那么你真正吸收的水量只有四盎司。

英国的这项研究检测了13种常见饮品在72位男性身体中的补水指数，这些受测者的年龄均在25岁左右，他们在测试初饮用了一公升的水作为参照标准。两小时后受测者体内水分含量 — 即未经由尿液流失的液体量 — 记录为1.0。然后以相似的方式测试其他饮料的补水指数，再将其与水的指数作比较。高于1.0的饮料的体内水分留存率高于水，低于1.0的饮料排出率高于水。

研究显示有四种饮料的补水指数远高于水，它们分别是以电解质液体为代表的口服补水溶液；脱脂牛奶；全脂牛奶和橙汁。前三种饮料的补水指数高达1.5左右，橙汁的补水指数为1.1，比水略高。

牛奶高效补水的原理是什么？通常当你摄取水分时，肾脏会收到通过产生尿液来排出多余水分的指令，但是若你饮用的液体含有营养成分和诸如钠和钾这样的电解质，比如饮用牛奶，那么胃的排空速率就会变慢，肾脏因此收到的指令变弱。

(Chinadaily.com.cn)

    Words to Learn 相关词汇

    【血糖的】xuètáng de glycemic related to the presence of glucose in blood

    【补水】bǔshuǐ rehydration the process of taking in or absorbing fluid after dehydration