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吃西瓜,降血压 精选

已有 6969 次阅读 2014-6-22 06:50 |个人分类:科普集萃|系统分类:科普集锦| 西瓜, 血压

在我知道西瓜对健康的这一好处之前,我就喜欢吃西瓜。在整个夏季,我几乎每天都要吃西瓜,而且特别喜欢吃冰冻西瓜(不提倡!)。

我生活在广东,广东人认为西瓜属于“寒湿”的食品,特别忌讳。我也在他们的影响下减少了食用量,但那样可能会降低西瓜的健康效应。

最近,美国科学家在《美国高血压杂志》(American J Hypertension)发表文章指出,西瓜可以明显降低超重者在静息时和胁迫下的血压。

早就发现,心脏病往往多发于寒冷的冬天,因为低温使血压升高,心脏不得不超负荷运转,以便将血液泵入动脉血管,这样就会导致流入心脏的血液减少。

肥胖及高血压人士在冬季或低温房间长时间滞留,突发中风或心力衰竭的风险极高,而多吃西瓜就能极大地降低心脏病的风险,只是冬天吃西瓜有点难!

西瓜中富含瓜氨酸,而瓜氨酸可以转变成精氨酸,精氨酸又能在血管内皮细胞一氧化氮合酶催化下转变成一氧化氮,而一氧化氮正是血管扩张剂。因此,若冬天买不到西瓜,就可以口服含有瓜氨酸的保健品(好像市售的都是精氨酸与瓜氨酸的混合物)。

该实验观察为期12周,在13名患高血压病的肥胖中年男女(女性10人,平均年龄57岁,收缩压约151毫米汞柱)中进行。为了模拟冬季气候,让参试者将一只手浸入华氏39度(摄氏4度)的水中,然后进行血压测量及其他测试

实验分两期进行,每期6周。将参试者分成两组,一组参试者每天服用2克瓜氨酸制品,另一组则服用安慰剂。在整个实验过程中,停止服用降压药,也不减肥和锻炼。

结果表明,瓜氨酸可使处于低温环境中的参试者血压下降约10毫米汞柱,心率下降约7.3%(以75次/分钟为标准)。从绝对值来看,血压降低的幅度并不大,但对于高血压病人而言,冬季或低温导致心脏病的原因也许就是血压的轻微上升而达到阈值。

另外,也有研究表明,西瓜汁对于缓解运动后肌肉酸痛很有益处,因此运动员或体力劳动者应该多喝西瓜汁或多吃西瓜。


New research suggests that watermelon can be an effective natural weapon against prehypertension, a precursor to cardiovascular disease.
Credit: iStockphoto/Serhiy Shullye


Chowing down on watermelon could lower blood pressure, study suggests

Date:
April 3, 2014
Source:
Florida State University
Summary:
Watermelon could significantly reduce blood pressure in overweight individuals both at rest and while under stress. "The pressure on the aorta and on the heart decreased after consuming watermelon extract," the small study concludes.


Be sure to pick up a watermelon -- or two -- at your local grocery store. It could save your life.

A new study by Florida State University Associate Professor Arturo Figueroa, published in the American Journal of Hypertension, found that watermelon could significantly reduce blood pressure in overweight individuals both at rest and while under stress.

"The pressure on the aorta and on the heart decreased after consuming watermelon extract," Figueroa said.

The study started with a simple concept. More people die of heart attacks in cold weather because the stress of the cold temperatures causes blood pressure to increase and the heart has to work harder to pump blood into the aorta. That often leads to less blood flow to the heart.

Thus, people with obesity and high blood pressure face a higher risk for stroke or heart attack when exposed to the cold either during the winter or in rooms with low temperatures.

So, what might help their hearts?

It turned out that watermelon may be part of the answer.

Figueroa's 12-week study focused on 13 middle-aged, obese men and women who also suffered from high blood pressure. To simulate cold weather conditions, one hand of the subject was dipped into 39 degree water (or 4 degrees Celsius) while Figueroa's team took their blood pressure and other vital measurements.

Meanwhile, the group was divided into two. For the first six weeks, one group was given four grams of the amino acid L-citrulline and two grams of L-arginine per day, both from watermelon extract. The other group was given a placebo for 6 weeks.

Then, they switched for the second six weeks.

Participants also had to refrain from taking any medication for blood pressure or making any significant changes in their lifestyle, particularly related to diet and exercise, during the study.

The results showed that consuming watermelon had a positive impact on aortic blood pressure and other vascular parameters.

Notably, study participants showed improvements in blood pressure and cardiac stress while both at rest and while they were exposed to the cold water.

"That means less overload to the heart, so the heart is going to work easily during a stressful situation such as cold exposure," Figueroa said.

Figueroa has conducted multiple studies on the benefits of watermelon. In the past, he examined how it impacts post-menopausal women's arterial function and the blood pressure readings of adults with pre-hypertension.

In addition to being published in the American Journal of Hypertension, the study was also published in the US National Library of Medicine National Institutes of Health and was one of the "top new hypertensive articles" in MDLinx.

Story Source:

The above story is based on materials provided by Florida State University. Note: Materials may be edited for content and length.

Journal Reference:

  1. A. Figueroa, A. Wong, R. Kalfon. Effects of Watermelon Supplementation on Aortic Hemodynamic Responses to the Cold Pressor Test in Obese Hypertensive Adults. American Journal of Hypertension, 2014; DOI:10.1093/ajh/hpt295
























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