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【科普】炎热的天气，会引起体重增加吗
Q. At 80 years old, I am in relatively good health, aside from a recent diagnosis of high blood pressure. Taking a beta blocker and watching my salt has brought my blood pressure down into the normal range. During a period of extreme heat this summer, my ankles were more swollen than usual, and my weight jumped three pounds in just two days. Was that because of the heat, or did salt have something to do with it?
A. Congratulations on getting good control of your blood pressure with a medication and salt restriction. Most people require two or three medications to control high blood pressure, but you are a good example of what salt restriction can do.
The "salt" we are discussing is sodium. Along with chloride, sodium makes table salt. Sodium is the primary agent that regulates the fluid level in the bloodstream as well as the fluids that bathe cells. Rapid changes in weight — like three pounds in two days — are almost always caused by taking in too much sodium from foods and beverages.
Your body carefully regulates the concentration of sodium in your body's fluids. When you take in more than your kidneys can flush out, sodium accumulates in the fluid between cells. Water inevitably follows sodium. As the volume of fluid bathing the cells increases, so does the volume of blood in the arteries and veins. This means more work for the heart and more pressure on blood vessels.
When I was in medical school, my professors drove home the connection between sodium and water with a demonstration that I remember to this day. The students weighed themselves at the beginning of class. Then half of the students drank a quart of tap water each, while the rest drank a quart of salt water. (I, unfortunately, got the salt water — yuck!) Before the lecture was over, many of those who had drunk the plain water were running off to the bathroom because their kidneys were busy eliminating the water. Those of us who drank the salt water didn't need to go because our kidneys were taking a while to flush out the sodium, so we retained the water. The next day, we reweighed ourselves at the beginning of class. My classmates who had drunk plain water weighed the same as they had the day before. Those of us who had drunk the salty water weighed a pound or so more, because our bodies were still hanging on to the sodium and water.
It is likely that during the hot weather you ate and drank more salty foods than usual, and this caused the jump in your weight and the swelling around your ankles. If this happens again, walking a lot and restricting your sodium should allow your body to return to normal in just a few days. But the lesson is the same one that I got in medical school: if you eat a lot of salt, it will stick with you for a while. On a practical level for you and others, restricting your sodium intake can limit the number of blood pressure medications you need. It will also likely lower your chances of having a stroke.
— Richard Lee, M.D.Associate editor, Harvard Heart Letter 极地科技动态 (2005年第2期) Polar Science and Technology文件类型:DOC/Microsoft Word- 文字版地球科学常设科学组下属的科普与教育小组在地学空间信息和地球科学信息的收集、整理... 评价生物群体生命率变动的时、空模式. 同时新开展一项针对幼海豹和成年母海豹体重...www.pric.gov.cn/...4000305.doc-2011-01-06-动态 (2005年第2期) Polar Science and Technology" 水为万物之始,财富藏在健康中,健康藏在水中!无备是生命的隐患,无...天气炎热时,因体内含有大量水,水的比热大,故体温升高不多.同时,天热出汗,汗水蒸发消耗... 使体内的酸碱达到动态平衡.如果过酸或过碱,都会引起血液氢离子浓度的改变,使正常的...hi.baidu.com/...g/category/知水篇-2009-04-12-快照-生命的隐患,无..." 弗诺·文奇科幻史诗:《天渊》--连载中...... - 科幻天地 - 环球科学...发表时间：2008-10-18回帖数：14作为对《球状闪电》的补充,在下将会以每日5~6章的速度为大家奉上 一百六十年后 第一... 场馆内部极尽豪奢.采用的是文明初级阶段的古典主义风格,和人类还没有掌握生命支持系...www.cpcwi.com/html/sciam/bb... - 2008-10-20-快照-科学..."[标签:content2]
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作者:admin@医学,生命科学 2011-01-22 13:09
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