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Harvard Health Publications -- Harvard Medical School HEALTHbeat
September 14, 2005

Dear HEALTHbeat subscriber,

The popular belief is that we need at least eight cups of water a day (along with the water we get from food and other drinks). However, there isn't much scientific evidence for the belief. This issue of HEALTHbeat discusses how much water we really need each day and how excessive water intake can affect the bladder.

Also in this issue, Dr. Celeste Robb-Nicholson, editor in chief of the Harvard Women’s Health Watch, discusses how the radiofrequency dermatological treatment known as Thermage can tighten the skin and reduce wrinkles.

Best wishes,
The Editors
The editors of Harvard Health Publications
Harvard Medical School

In This Issue
1 How much water do you need?
2 Notable from Harvard Medical School:
* Improving Memory:
   Understanding and
   preventing age-related
   memory loss
* Skin Care and Repair
3 Question and answer with Dr. Celeste Robb-Nicholson:
How does Thermage remove wrinkles?

From Harvard Medical School
Better Bladder and Bowel Control

Incontinence is a surprisingly common problem, but one that is rarely discussed. But there are a variety of treatment options available, including exercise programs, medications, and surgery. If you suffer from a lack of bladder or bowel control, this report will explain the many causes of urinary and bowel incontinence, and provide reassurance and treatment options tailored to the specific cause.

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Buy our special health reports online and save $8 off the cover price—that's 33%!

1\ How much water should you drink?

We’ve heard it for decades: Drink at least 8 cups of water a day. Not only can three out of four adults recite this bit of health wisdom, but many even feel guilty if they don’t meet the standard. However, this advice may be based on a misunderstanding. Some trace it to the 1940s, when the National Academy of Sciences published a recommended daily allowance of 1 milliliter of fluid for each calorie burned—a little over 8 cups for a typical 2,000-calorie diet. However, the statement also explained that most of this fluid could be obtained via the liquid contained in foods.

Regardless, the 8-glasses-a-day dictum caught on. Today people frequently consume much more as they tote giant water bottles, buy super-size soft drinks, and follow programs that promise you can lose weight by drinking as much as a quart of fluid at a time.

Also, those who choose to participate in such a diet may forget an important fact if they’re coffee drinkers: Caffeine is a diuretic – it encourages the kidneys to produce urine so effectively that it may contribute to mild dehydration. In moderation, there is little to worry about; but heavy consumers of caffeine may find a faster flow of fluids through their body, requiring a greater consumption of non-caffeinated liquids.

In a 2000 survey conducted for Rockefeller University and the International Bottled Water Association, 2,818 adults in 14 cities reported drinking about 6 cups of water a day—a result that was presented as alarming evidence that Americans are becoming dehydrated. But if you include the sodas, coffee, tea, milk, juice, sports drinks, and alcoholic beverages these respondents drank, their average fluid consumption was 17.6 cups a day—enough to have you urinating every waking hour, even if you don’t have any problem with bladder capacity.

More recently, a kidney specialist at Dartmouth Medical School searched the scientific literature for studies that might support the idea that people need 8 glasses of fluid a day. Not only did he determine that no such evidence exists, but concluded that the research that has been done "strongly suggests that such large amounts are not needed."

Fluids and incontinence

If you have an incontinence problem, the below tips might help improve your symptoms. Unless you engage in strenuous exercise or have a medical condition (such as a propensity toward forming kidney stones) that requires more fluid consumption:

Aim for no more than 6–8 cups of fluid (from all sources) each day.

Don’t drink more than 8 ounces at a time.

Don’t guzzle. The faster your bladder fills, the more likely you are to feel urgency.

Minimize caffeinated and carbonated drinks.

Decrease or eliminate alcohol consumption.

If you are thirsty because it is hot or you have exercised, don’t hesitate to drink water.

For more information on urinary and bowel incontinence, order our special health report, Better Bladder and Bowel Control.


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2\ Notable from Harvard Medical School
** Improving Memory: Understanding and preventing age-related memory loss

If you’re like most people, you may worry that your memory isn’t as sharp as it used to be — that it’s becoming more challenging to learn new things, remember something you just heard, or recall facts. However, memory loss is not an inevitable part of aging. Improving Memory: Understanding and preventing age-related memory loss is a practical guide to the causes of memory loss and the steps you can take to improve your ability to learn and remember for a lifetime.

** Skin Care and Repair

Time and sun are the biggest enemies to healthy skin. Dermatologists continue to fight these challenges with high-tech treatments and advice to patients. Skin Care and Repair will help you protect your skin with advice on how to deal with problems that can arise, including everything from dry skin to cancer. You’ll also learn of the newest cosmetic treatments such as photorejuvenation and laser resurfacing, and will receive sound advice to protect yourself before a problem arises.


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3\ Q&A: How does Thermage remove wrinkles?

Q: Can you tell me anything about a new cosmetic treatment called Thermage?

A: Thermage uses heating and cooling to tighten skin and reduce wrinkles. In 2001, the FDA approved it for treating forehead wrinkles and fine lines around the eyes. It’s also approved for treating sagging jowls and cheeks.

Skin is composed of several layers. The outer layer is the epidermis. Just beneath it is a thicker layer called the dermis. Below the dermis lies a layer of fat, and under that, muscle tissue. The dermis is composed of collagen proteins arranged in parallel layers of fiber called fibrils; these form a matrix that holds skin together. As we age, the fibril layers loosen and become less organized, resulting in sagging skin.

Thermage heats the dermis without damaging the epidermis. A hand-held device delivers radiofrequency energy into dermal tissue while a cooling spray protects the epidermis. When the dermal tissue is heated, the collagen fibrils become disrupted, then contract and thicken, tightening the skin layer below the surface. As the fibril layers heal, they are reshaped and new collagen forms. This tightens the skin even more. Some improvement may be visible immediately, but the full effects probably won’t be evident for a few weeks up to six months.

Thermage takes 30 minutes to two hours, depending upon how much skin area is treated. Unlike more invasive cosmetic surgeries, it doesn’t require a prolonged recovery period, but it can cause swelling for two to three days. Risks include burns, scars, and temporary bumps. A few patients develop small, permanent indentations in the skin, possibly because of heat damage to the fat layer below the dermis. And the procedure is painful. An anesthetic cream applied to the face beforehand helps but doesn’t entirely eliminate the pain. Follow-up studies are needed, but according to the maker of the Thermage system, results may last 24 months or more.

Thermage is expensive — ranging from $2,500 to $4,000 — and it isn’t covered by health insurance. It’s impossible to predict exactly how much it will tighten any individual’s skin. And it doesn’t lift muscle, like a traditional facelift, so it’s not as useful for people with advanced wrinkling or very saggy skin. Thermage is probably best for people in their 30s to 40s who have a few wrinkles or mild skin looseness.

Celeste Robb-Nicholson, M.D., is Editor in Chief of Harvard Women’s Health Watch (


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Harvard Medical School offers special reports on over 50 health topics. Visit our website at to find reports of interest to you and your family.

Copyright 2005 by the President and Fellows of Harvard College.
To view our archive of past HEALTHbeat e-newsletters click here.
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