08 July, 2011
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Drinking Water & Blood Pressure
One in three American adults suffers from hypertension, or high blood pressure, according to the American Heart Association. Although rare, low blood pressure, or hypotension, is equally dangerous. Fortunately, in many cases, certain lifestyle changes can help you maintain or restore healthy blood pressure levels. Being conscientious about the amount and quality of the water you drink is one of these changes.
Blood pressure readings typically include two numbers given in millimeters of mercury, or mm Hg. The systolic pressure reflects the pressure during heart contractions, while the diastolic pressure occurs in between heartbeats. The American Heart Association defines high blood pressure as systolic pressure exceeding 140 mm Hg, or diastolic pressure above 90 mm Hg. In contrast, you're considered hypotensive if your systolic and diastolic pressures are below 90 and 60 mm Hg, respectively.
Short-Term Blood Pressure Regulation
Your body continuously monitors your blood pressure, and is ready to make adjustments on a minute-to-minute basis, physiologist Linda Constanzo remarks. Whenever dehydration causes your blood pressure to fall, pressure detectors called "baroreceptors" quickly respond, causing a fourfold response in your body: your heart rate increases; heart contractions increase to push more blood to organs; and your small arteries and veins become constricted to conserve water.
Long-Term Blood Pressure Regulation
Chronic dehydration triggers a slower, hormone-based mechanism to adjust blood volume and increase blood pressure. According to Dr. Constanzo, this mechanism causes the kidneys to reabsorb sodium, leading to increased fluid levels in the body. In addition, a thirst signal is issued, and your small arteries constrict. In contrast, the more water you drink, the more fluid your kidneys excrete as urine, explains physician Julian Whitaker. Because there's less need to conserve water, your small blood vessels open up, and blood pressure goes down.
Few people consciously drink the recommended eight to ten eight-ounce glasses of water per day. Yet most of us are aware that this is the minimum that's recommended to make up for daily fluid losses through sweat, urination and respiration. According to Dr. Whitaker, if you have hypertension, your goal should even be higher, aiming for 10 to 12 eight-ounce glasses, or 96 ounces of water every day.
Every day, a multitude of contaminants enters water sources, including industrial or municipal waste, as well as runoff from cities or agricultural areas. Potential water contaminants, according to the Environmental Protection Agency, include: disinfectants; disinfection byproducts, heavy metals and other chemicals; and radioactive contaminants. The EPA also associates higher cloudiness, or turbidity, in the water with higher levels of disease-causing microorganisms such as viruses, parasites and some bacteria.
The quality of the water you drink is just as important as its quantity. Bottled water is a possible alternative to tap water, but is expensive in the long-term and poorly regulated. A better option is to invest in a home filtering system that removes harmful contaminants, including chlorine, heavy metals and disease-causing organisms. According to Dr Whitaker, the best type of water purifiers combine an activated solid carbon block filter with an ultraviolet light chamber.
Dehydrating beverages, such as alcohol, coffee and tea, increase your need for water replacement. Other things that can cause your body to lose more water than usual include physical exercise, diarrhea, fever, kidney disease and diabetes, says Dr. Whitaker. While water is arguably the best diuretic, consult your doctor before increasing your intake, especially if you have a kidney disorder or congestive heart disease.
- American Heart Association: High Blood Pressure Statistics
- Mayo Clinic: Low Blood Pressure
- Environmental Protection Agency: Drinking Water Contaminants
- "Reversing Hypertension;" Julian Whitaker, M.D.; 2000
- "Physiology" (7th Edition) Linda Constanzo, Ph.D.; 2007
- glass with water image by Alexander Ivanov from Fotolia.com