Month: July 2022

Driving along the freeway recently, a billboard caught my eye. In bold letters it proclaimed:

Milk hydrates better than water.

Wait, could this be true? And if so, should I be rehydrating with milk after a workout? And should we all have milk, rather than water, in our water bottles?

What’s behind the claim?

Unsurprisingly, the ad is sponsored by the milk industry. And while I’d never heard this claim before, the studies behind the idea aren’t particularly new or compelling. The website supporting this ad cites three small studies dating back more than a decade:

• A 2007 study enrolled 11 volunteers (five men, six women) who exercised until they were markedly dehydrated on several occasions. Each time they rehydrated with a different drink, and their urine output was measured over the following five hours. After drinking milk, the study volunteers produced less urine (and therefore retained more fluid) than with water or a sports drink (Powerade). Therefore, milk was considered to provide better hydration.
• A study published in 2016 described seven men with marked dehydration following exercise who drank fat-free milk, water, or Powerade. The results were similar.
• A 2016 study enrolled 72 healthy, well-hydrated men who drank various fluids and then had their urine production measured over the next four hours. The drinks used in this study were water, whole milk, skim milk, beer, Dioralyte (an oral rehydration solution used after fluid loss from diarrhea), tea, coffee, diet cola, regular cola, orange juice, and Powerade. The researchers found that fluid retention was best after drinking either type of milk or the oral rehydration solution; results for the other drinks were similar to water.

Sounds like milk is a winner, right? Maybe. But there are other things to consider.

The study details matter

The findings of these studies aren’t definitive. As with all research, there are important limitations. For example:

• The small number of participants in these studies means that just a few people could have an outsized impact on the results.
• Two of the three studies involved significant dehydration by intensely exercising in a warm environment, leading to several pounds of fluid loss. Therefore, the results may not apply to people engaged in more typical daily activities or workouts. In addition, the studies equated better hydration with less urine production in the hours after drinking various fluids. This is only one way to define hydration, and not clearly the best one.
• The advantage of milk reported in these studies may be too small or too temporary to matter much. For example, in the study of 72 people, milk drinkers produced about 37 ounces of urine over four hours while water drinkers produced 47 ounces. Does the 10-ounce difference have a meaningful health impact? If the study participants had been monitored for a longer period, would this difference disappear?
• The amount of milk consumed in the study of seven men would contain more than 1,000 calories. That may be acceptable for an elite athlete after hours of intensive exercise in the heat, but counterproductive and costly for someone working out for 30 minutes to help maintain or lose weight. Tap water is free and has no calories!

Hyping hydration: Many claims, little evidence

The billboard promoting milk reflects our relatively recent focus on hydration for health. This is promoted — or perhaps created — by advertisers selling sports drinks, energy drinks and, yes, water bottles. But does drinking “plenty of water” translate to weight loss, athletic performance, and glowing appearance? Does monitoring urine color (darker could indicate dehydration) and downing the oft-recommended eight glasses of water daily make a difference in our health? On the strength of evidence offered so far, I’m not convinced.

But wait, there’s more! Emotional support water bottles, a trend popularized recently in Australia, offer one part public expression of your commitment to health and one part security blanket. (Yes, it’s a thing: #emotionalsupportwaterbottle has more than 80 million views on TikTok.) And then there’s intravenous hydration on demand for healthy (and often wealthy) people convinced that intravenous fluids will improve their looks, relieve their hangovers, help with jet lag, or remedy and prevent an assortment of other ailments.

Is this focus on hydration actually helpful?

Before water bottles were everywhere and monitoring fluid intake became commonplace, medically important dehydration wasn’t a problem for most healthy people who were not rapidly losing fluids due to heat, intense exercise, diarrhea, or the like.

The fact is, drinking when thirsty is a sound strategy for most of us. And while there are important exceptions noted below, you probably don’t need fluids at hand at all times or to closely monitor daily fluid intake to be healthy. There are far more important health concerns than whether you drink eight glasses of water each day.

When is dehydration a serious problem?

Weather, exercise, or illness can make dehydration a major problem. Particularly susceptible are people who work or exercise outside in hot and humid environments, those at the extremes of age, people experiencing significant fluid loss (as with a diarrheal illness), and those without reliable access to fluids. If significant dehydration occurs, replacing lost fluids is critically important, and may even require a medical setting where intravenous fluids can be provided quickly.

The bottom line

Despite the claims of milk ads and the iffy studies justifying them, the idea of replacing water with milk for rehydration may not convince everyone: the taste, consistency, and extra calories of milk may be hard to get past.

As for me, until there’s more convincing evidence of an actual health advantage of milk over water for routine hydration, I’ll stick with water. But I’ll forego the water bottle.

Follow me on Twitter @RobShmerling

About the Author

Robert H. Shmerling, MD,

Senior Faculty Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Robert H. Shmerling is the former clinical chief of the division of rheumatology at Beth Israel Deaconess Medical Center (BIDMC), and is a current member of the corresponding faculty in medicine at Harvard Medical School. … See Full Bio View all posts by Robert H. Shmerling, MD

A visit with a surgeon can be overwhelming. You may feel anxious about your planned surgery. Many questions could be swirling in your head during a rushed visit. While surgeons have a reputation as technical specialists, bedside manner may be lacking at times.

It sounds simple, but setting the right expectations — on both sides — can ease your anxiety and help you feel more comfortable during a visit with your surgeon. So what exactly does this mean? And how can you accomplish it?

Tell your story

Tell your story to help set clear goals. Beyond simply stating what hurts or what is not working, be sure to include details such as

• how your current condition limits what you enjoy doing
• your daily activities
• how your condition affects your relationship with your social circle and family
• upcoming plans or goals such as travel, or life events like vacations or weddings.

Sharing details like these helps you collaborate to define a successful outcome for surgery.

Listen with your goals in mind

When explaining surgical options, surgeons are obligated to discuss key information, including risks, potential complications, and likely outcomes. Encourage your surgeon to put these facts into context based on what is important to you.

• Ask questions about how surgery will affect things you enjoy doing, such as playing pickleball, taking walks, cooking, reading, or listening to music.
• Ask what you should realistically expect during recovery and once you have recovered. For example, if you have a vacation or travel planned, be sure to discuss how surgery will affect your plans.

Define success before your surgery

Once you are confident that you have told your story and feel like you and your surgeon have set appropriate expectations, take the next step. Ask whether this discussion affects your surgeon’s approach to surgery, and explore how you each define surgical success.

Often, both surgeon and patient agree on a definition of success: for example, remove the entire tumor. But this simple definition may leave room for misalignment. Let’s say a surgeon is able to entirely remove a thyroid tumor, but now the patient speaks in a hoarse voice. While technically successful, this surgery may feel like a failure unless the person understood and accepted the risk that it could affect how they speak.

This highlights the importance of setting expectations. In this example, clear speech after surgery might be your expectation as a patient. Your surgeon must balance explaining how surgical risks might affect that expectation with the reality of treating the condition. Surgery is more likely to feel successful if both sides discuss and align their expectations.

Give yourself time when possible

Processing information about surgery can take time. A surgeon may have to provide realistic expectations that do not align with your initial expectations and hopes.

Some surgeries are urgent, others are not. If you do not need to make an immediate decision, be open with your surgeon. Let them know that you need time to consider the surgeon’s definition of success and your own. Reflecting on the discussion can reduce the stress and anxiety you’re likely to feel during an initial visit.

The bottom line: Making the most of your appointment

Communication goes two ways during a good pre-surgery visit. Do your best to tell your story and emphasize details of your life that are important. When listening, ensure that your surgeon acknowledges these details and describes how surgery may affect your life, as opposed to simply stating technical facts about the surgery. Setting expectations together will help you achieve a common goal and establish a strong surgeon-patient relationship that is essential for a positive surgical outcome.

About the Author

James Naples, MD,

Contributor; Editorial Advisory Board Member, Harvard Health Publishing

Dr. James Naples is a physician at Beth Israel Deaconess Medical Center, and a clinical instructor at Harvard Medical School in Boston, MA. He earned his medical degree from the University of Connecticut School of Medicine, … See Full Bio View all posts by James Naples, MD

We can feel groggy when our sleep schedule is thrown off even just a little. So what happens when shift work requires people to regularly stay awake through the night and sleep during the day — and how can they protect their health and well-being?

What is shift work disorder?

Mounting evidence, including several new studies, paints a worrisome picture of the potential health fallout of nontraditional shift work schedules that affect 15% to 30% of workers in the US and Europe, including factory and warehouse workers, police officers, nurses, and other first responders.

So-called shift work disorder mainly strikes people who work the overnight or early morning shift, or who rotate their shifts, says Eric Zhou, an assistant professor in the Division of Sleep Medicine at Harvard Medical School. It is characterized by significant problems falling and staying asleep, or sleeping when desired. That’s because shift work disrupts the body’s normal alignment with the 24-hour sleep-wake cycle called the circadian rhythm.

“People who work 9-to-5 shifts are typically awake when the sun is up, which is aligned with their body’s internal circadian clock. But for shift workers, their work hours and sleep hours are misaligned with the natural cues to be awake or asleep,” Zhou says. “They’re working against the universe’s natural inclinations — not just their body’s.”

What’s the connection between shift work and health?

A 2022 research review in the Journal of Clinical Sleep Medicine links shift work to higher risks for serious health problems, such as heart attack and diabetes. This research suggests adverse effects can include metabolic syndrome (a cluster of conditions that raises the risks for heart disease, diabetes, and stroke), accidents, and certain types of cancer.

“The research is consistent and powerful,” Zhou says. “Working and sleeping during hours misaligned with natural light for extended periods of time is not likely to be healthy for you.”

How do new studies on shift work boost our understanding?

New research continues to add to and strengthen earlier findings, teasing out specific health effects that could stem from shift work.

• Shift workers on rotating schedules eat more erratically and frequently than day workers, snack more at night, and consume fewer healthier foods with potentially more calories, a study published online in Advances in Nutrition suggests. This analysis reviewed 31 prior studies involving more than 18,000 participants, comparing workers’ average food intake over 24 hours.
• Disrupting the circadian rhythm through shift work appears to increase the odds of colorectal cancer, a malignancy with strong ties to lifestyle factors, according to a 2023 review of multiple studies published online in the Journal of Investigative Medicine. Contributors to this higher risk may include exposure to artificial light at night, along with complex genetic and hormonal interactions, study authors said.

“Cancer understandably scares people, and the World Health Organization recognizes that shift work is a probable carcinogen,” Zhou says. “The combination of chronically insufficient and poor-quality sleep is likely to get under the skin. That said, we don’t fully understand how this happens.”

How can you protect your sleep — and your health?

If you work overnight or early morning shifts, how can you ensure you sleep more soundly and restfully? Zhou offers these evidence-based tips.

Time your exposure to bright and dim light. Graveyard shift workers whose work schedule runs from midnight through 8 a.m., for example, should reduce their light exposure as much as possible after leaving work if they intend to go right to sleep once they return home. “These measures could take the form of wearing blue light–blocking glasses or using blackout shades in your bedroom,” he says.

Make enough time for sleep on days off. “This is often harder than it sounds, because you’ll want to see your family and friends during nonwork hours,” Zhou says. “You need to truly protect your opportunity for sleep.”

Maintain a consistent shift work schedule. “Also, try to minimize the consecutive number of days you spend working challenging shifts,” he says.

Talk to your employer. Perhaps your boss can schedule you for fewer overnight shifts. “You can also ask your doctor to make a case for you to be moved off these shifts or have more flexibility,” Zhou says.

Look for practical solutions that allow you to get more restful sleep. “People engaged in shift work usually have responsibilities to their job as well as their family members, who often operate under a more typical 9-to-5 schedule,” he notes. “The goal is to preserve as strong a circadian rhythm as possible under the abnormal schedule shift work requires.”

About the Author

Maureen Salamon, Executive Editor, Harvard Women's Health Watch

Maureen Salamon is executive editor of Harvard Women’s Health Watch. She began her career as a newspaper reporter and later covered health and medicine for a wide variety of websites, magazines, and hospitals. Her work has … See Full Bio View all posts by Maureen Salamon