Month: June 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

In today’s fast-paced world, our waking hours are filled with decisions — often surrounding what to eat. After a long day, dinner could well be fast food or takeout. While you may worry about the toll food choices take on your waistline or blood pressure, as a liver specialist, I also want to put fatty liver disease on your radar.

One variant, officially called nonalcoholic fatty liver disease (NAFLD), now affects one in four adults globally. Sometimes it progresses to extensive scarring known as cirrhosis, liver failure, and higher risk for liver cancer. The good news? Fatty liver disease can be prevented or reversed.

What is fatty liver disease?

Fatty liver disease is a condition caused by irritation to the liver. Liver tissue accumulates abnormal amounts of fat in response to that injury. Viral hepatitis, certain medicines (like tamoxifen or steroids, for example), or ingesting too much alcohol can all cause fatty liver disease.

However, NAFLD has a different trigger for fat deposits in the liver: a group of metabolic risk factors. NAFLD is most common in people who have high blood pressure, high cholesterol, insulin resistance (prediabetes), or type 2 diabetes. It is also common among people who are overweight or obese, though it is possible to develop NAFLD even if your body mass index (BMI) is normal.

What helps prevent or reverse NAFLD?

Diet can play a huge role. Because NAFLD is so closely tied to metabolic health, eating more healthfully can help prevent or possibly even reverse it. A good example of a healthful eating pattern is the Mediterranean diet.

Overweight or obesity is a common cause of NAFLD. A weight loss program that includes activity and healthy eating can help control blood pressure, cholesterol, and blood sugar. Among the many healthful diet plans that help are the DASH diet and the Mediterranean diet. Talk to your doctor or a nutritionist if you need help choosing a plan.

To vigorously study any diet as a treatment for fatty liver disease, researchers must control many factors. Currently, no strong evidence supports one particular diet over another. However, the research below highlights choices to promote a healthy liver.

Avoid fast food

A recent study in Clinical Gastroenterology and Hepatology linked regular fast-food consumption (20% or more of total daily calories) with fatty liver disease — especially in people who had type 2 diabetes or obesity. Fast foods tend to be high in saturated fats, added sugar, and other ingredients that affect metabolic health.

Steer clear of soft drinks and added sugars

Soft drinks with high-fructose corn syrup, or other sugar-sweetened beverages, lead directly to large increases in liver fat deposits, independent of the total calories consumed. Read labels closely for added sugars, including corn syrup, dextrose, honey, and agave.

Instead of sugary drinks, sip plain water. Black coffee or with a splash of cream is also a good pick; research suggests coffee has the potential to decrease liver scarring.

Avoid alcohol

Alcohol directly damages the liver, lacks nutritional value, and may affect a healthy microbiome. If you have NAFLD, it’s best to avoid any extra cause for liver injury. We simply do not know what amount of alcohol is safe for those with fatty liver disease — even social drinking may be too much.

Eat mostly whole foods

Vegetables, berries, eggs, poultry, grass-fed meats, nuts, and whole grains all qualify, but cutting out red meat may be wise. An 18-month trial enrolled 294 people with abdominal obesity and lipid imbalances such as high triglycerides. Regular activity was encouraged, and participants were randomly assigned to one of three diets: standard healthy dietary guidelines, a traditional Mediterranean diet, or a green-Mediterranean diet. (The green-Med diet nixed red and processed meats and added green tea and a dinner replacement shake rich in antioxidants called polyphenols.)

All three groups lost some weight, although the Mediterranean diet groups lost more weight and kept it off for a longer period. Both Mediterranean diet groups also showed reduced liver fat at the end of 18 months, but liver fat decreased twice as much in the green-Med group as in the traditional Mediterranean diet group.

Healthy fats are part of a healthy diet

We all need fat. Dietary fats help your body absorb vitamins and are vital in the protection of nerves and cells. Fats also help you feel satisfied and full, so you’re less likely to overeat. Low-fat foods often substitute sugars and starches, which affect blood sugar regulation in our bodies. But all fat is not created equal.

It’s clear that Mediterranean-style diets can help decrease liver fat, thus helping to prevent or possibly reverse NAFLD. These diets are high in healthful fats, such as monounsaturated fats found in olive oil and avocados and omega-3 fats found in walnuts and oily fish like salmon and sardines.

With so many choices, it’s hard to know where to start in the healthy eating journey. Let’s strive to eat whole foods in their natural state. Our livers will thank us for it.

About the Author

Kathleen Viveiros, MD, Contributor

Dr. Kathleen Viveiros is a clinical hepatologist at Brigham and Women’s Hospital who sees patients in Boston and in Foxborough and Westwood, MA. She is an instructor in medicine at Harvard Medical School. Her professional interests … See Full Bio View all posts by Kathleen Viveiros, MD

Low energy, brain fog, and lung problems are a few of the lingering aftereffects reported by some people who have had COVID-19. Could gut troubles also fall among the constellation of chronic symptoms that people with long-haul COVID experience? And if so, what do experts suggest to help ease this?

What happens to the gut during a COVID infection?

As we head into the fourth year since COVID-19 became a global health emergency, hundreds of millions of people around the globe have been infected with the virus that causes it. Since 2020, we’ve known that the virus particles that cause lung illness also infect the gastrointestinal (GI) tract: the esophagus, stomach, small intestines, and colon. This can trigger abdominal pain and diarrhea, which often — but not always — clear up as people recover.

We know chronic gut problems such as irritable bowel syndrome (IBS) sometimes occur even after illness caused by microorganisms like Campylobacter and Salmonella are cured. Could this happen with COVID-19?

What is long COVID?

While most people who get COVID-19 will survive, medical science is becoming aware of a group of people suffering from lasting declines in health. Well-reported long COVID aftereffects include tiredness, breathing difficulty, heart rhythm changes, and muscle pain. But few people, even in the medical field, are aware that long COVID symptoms may include chronic diarrhea and abdominal pain.

Why might the gut be involved in long COVID?

It is not clear why chronic gut symptoms might occur after a COVID-19 infection. One possible insight is a well-known syndrome called post-infectious irritable bowel syndrome (IBS) that may occur after a stomach flu (gastroenteritis).

Long after the bug causing the illness is gone, a change in gut-brain signaling may occur. A complex network of nerves connects the gut and the brain, and controls communication between different parts of the gut. These nerves tell body organs to produce digestive juices, alert you to the need to go to the bathroom, or prevent you from having another serving of stuffing at the Thanksgiving table.

The nerve network of the gut is so complicated that it is sometimes called the second brain. When the nerves are working well, you won’t notice a thing: you eat without pain, you move your bowels with ease, you have no GI worries. But what if the nerves are not working well? Then, even if the process of digestion remains normal, you may frequently have symptoms like pain or a distressing change in your bowel movements, such as diarrhea or constipation.

Once known as functional GI disorders, these health problems are now called disordered gut-brain interactions (DGBIs). When viruses and bacteria infect the gut, experts believe they may prompt a change in gut-brain signaling that can cause a DGBI like IBS to develop.

What to do if you’re noticing long-lasting gut problems after COVID-19 infection

We still do not know conclusively if COVID-19 can cause a long-term change in gut-brain messaging that leads to IBS or other disordered gut-brain interactions. But increasing evidence suggests that GI distress lasting six months or longer might be a symptom of long COVID. While we wait for more evidence, some GI specialists, including myself, recommend trying approaches that help relieve irritable bowel syndrome and other DGBIs.

If you are suffering from chronic abdominal pain and a change in your bowel movements after having had COVID-19, talk to your primary care doctor. Many health conditions have similar symptoms, including viral or bacterial infections, inflammation, or even cancers. A thorough exam can help to rule out certain conditions.

If the problem persists, do not suffer alone or feel embarrassed to act! Seek help if severe pain or changes in bowel movements are harming your quality of life or affecting daily activities. Talk with your doctor about the possibility that your chronic gut symptoms might be a form of long COVID. Find out if they can recommend helpful treatments or suggest a referral to a GI specialist. As research continues, new information may be available.

About the Author

Christopher D. Vélez, MD, Contributor

Dr. Christopher Vélez is an attending gastroenterologist in the Center for Neurointestinal Health of Massachusetts General Hospital's division of gastroenterology and the MGH department of medicine. He focuses on neurogastroenterology and motility disorders of the esophagus, … See Full Bio View all posts by Christopher D. Vélez, MD

Be honest: just how much television are you watching? One study has estimated that half of American adults spend two to three hours each day watching television, with some watching as much as eight hours per day.

Is time spent on TV a good thing or a bad thing? Let's look at some of the data in relation to your risks for cognitive decline and dementia.

Physical activity does more to sharpen the mind than sitting

First, the more time you sit and watch television, the less time you have available for physical activity. Getting sufficient physical activity decreases your risk of cognitive impairment and dementia. Not surprisingly, if you spend a lot of time sitting and doing other sedentary behaviors, your risk of cognitive impairment and dementia will be higher than someone who spends less time sitting.

Is television actually bad for your brain?

Okay, so it's better to exercise than to sit in front of the television. You knew that already, right?

But if you're getting regular exercise, is watching television still bad for you? The first study suggesting that, yes, television is still bad for your brain was published in 2005. After controlling for year of birth, gender, income, and education, the researchers found that each additional hour of television viewing in middle age increased risk for developing Alzheimer's disease 1.3 times. Moreover, participating in intellectually stimulating activities and social activities reduced the risk of developing Alzheimer's.

Although this study had fewer than 500 participants, its findings had never been refuted. But would these results hold up when a larger sample was examined?

Television viewing and cognitive decline

In 2018, the UK Biobank study began to follow approximately 500,000 individuals in the United Kingdom who were 37 to 73 years old when first recruited between 2006 and 2010. The demographic information reported was somewhat sparse: 88% of the sample was described as white and 11% as other; 54% were women.

The researchers examined baseline participant performance on several different cognitive tests, including those measuring

• prospective memory (remembering to do an errand on your way home)
• visual-spatial memory (remembering a route that you took)
• fluid intelligence (important for problem solving)
• short-term numeric memory (keeping track of numbers in your head).

Five years later, many participants repeated certain tests. Depending on the test, the number of participants evaluated ranged from 12,091 to 114,373. The results of this study were clear. First, at baseline, more television viewing time was linked with worse cognitive function across all cognitive tests.

More importantly, television viewing time was also linked with a decline in cognitive function five years later for all cognitive tests. Although this type of study cannot prove that television viewing caused the cognitive decline, it suggests that it does.

Further, the type of sedentary activity chosen mattered. Both driving and television were linked to worse cognitive function. But computer use was actually associated with better cognitive function at baseline, and a lower likelihood of cognitive decline over the five-year study.

Television viewing and dementia

In 2022, researchers analyzed this same UK Biobank sample with another question in mind: Would time spent watching television versus using a computer result in different risks of developing dementia over time?

Their analyses included 146,651 people from the UK Biobank, ages 60 and older. At the start of the study, none had been diagnosed with dementia.

Over 12 years, on average, 3,507 participants (2.4%) were diagnosed with dementia. Importantly, after controlling for participant physical activity:

• time spent watching television increased the risk of dementia
• time spent using the computer decreased the risk of dementia.

These changes in risk were not small. Those who watched the most television daily — more than four hours — were 24% more likely to develop dementia. Those who used computers interactively (not passively streaming) more than one hour daily as a leisure activity were 15% less likely to develop dementia.

Studies like these can only note links between behaviors and outcomes. It's always possible that the causation works the other way around. In other words, it's possible that people who were beginning to develop dementia started to watch television more and use the computer less. The only way to know for sure would be to randomly assign people to watch specific numbers of hours of television each day while keeping the amount of exercise everyone did the same. That study is unlikely to happen.

The bottom line

If you watch more than one hour of TV daily, my recommendation is to turn it off and do activities that we know are good for your brain. Try physical exercise, using the computer, doing crossword puzzles, dancing and listening to music, and participating in social and other cognitively stimulating activities.

About the Author

Andrew E. Budson, MD, Contributor; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Andrew E. Budson is chief of cognitive & behavioral neurology at the Veterans Affairs Boston Healthcare System, lecturer in neurology at Harvard Medical School, and chair of the Science of Learning Innovation Group at the … See Full Bio View all posts by Andrew E. Budson, MD