Month: August 2022

Turns out that when your mother told you to stop sitting near the TV or you might need glasses, she was onto something.

Myopia, or nearsightedness, is a growing problem worldwide. While a nearsighted child can see close objects clearly, more distant objects look blurry. Part of this growing problem, according to experts, is that children are spending too much time indoors looking at things close to them rather than going outside and looking at things that are far away.

What is nearsightedness?

Nearsightedness is very common, affecting about 5% of preschoolers, 9% of school-age children, and 30% of teens. But what worries experts is that over the last few decades its global prevalence has doubled — and during the pandemic, eye doctors have noticed an increase in myopia.

Nearsightedness happens when the eyeball is too large from front to back. Genes play a big role, but growing research shows that there are developmental factors. The stereotype of the nerd wearing glasses actually bears out; research shows that the more years one spends in school, the higher the risk of myopia. Studies also show, even more reliably, that spending time outdoors can decrease a child’s risk of developing myopia.

Why would outdoor time make a difference in nearsightedness?

While surprising, this actually makes some sense. As children grow and change, their lifestyles affect their bodies. A child who is undernourished, for example, may not grow as tall as they might have if they had better nourishment. A child who develops obesity during childhood is far more likely to have lifelong obesity. And the eyes of a child who is always looking at things close to him or her might adjust to this — and lose some ability to see far away.

Nearsightedness has real consequences. Not only can it cause problems with everyday tasks that require you to see more than a few feet away, such as school or driving, but people with myopia are at higher risk of blindness and retinal detachment. The problems can’t always be fixed with a pair of glasses.

What can parents do?

• Make sure your child spends time outdoors regularly — every day, if possible. That’s the best way to be sure that they look at things far away. It’s also a great way to get them to be more active, get enough Vitamin D, and learn some important life skills.
• Try to limit the amount of time your child spends close to a screen. These days, a lot of schoolwork is on screens, but children are also spending far too much of their playtime on devices rather than playing with toys, drawing, or other activities. Have some ground rules. The American Academy of Pediatrics recommends no more than two hours of entertainment media a day, and has a great Family Media Plan to help families make this happen.
• Have your child’s vision checked regularly. Most pediatricians do regular vision screening, but it is important to remember that basic screening can miss vision problems. It’s a good idea for your child to have a full vision examination from an ophthalmologist or an optometrist by kindergarten.
• Call your pediatrician or child’s eye doctor if you notice signs of a possible vision problem, such as
  • sitting close to the television or holding devices close to the face
  • squinting or complaining of any difficulty seeing
  • not being able to identify objects far away (when you go for walks, play I Spy and point to some far-away things!)
  • avoiding or disliking activities that involve looking close, like doing puzzles or looking at books, which can be a sign of hyperopia (farsightedness)
  • tilting their head to look at things
  • covering or rubbing an eye
  • one eye that turns inward or outward.

If you have any questions or concerns about your child’s vision, talk to your pediatrician.

Follow me on Twitter @drClaire

About the Author

Claire McCarthy, MD, Senior Faculty Editor, Harvard Health Publishing

Claire McCarthy, MD, is a primary care pediatrician at Boston Children’s Hospital, and an assistant professor of pediatrics at Harvard Medical School. In addition to being a senior faculty editor for Harvard Health Publishing, Dr. McCarthy … See Full Bio View all posts by Claire McCarthy, MD

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

Snuff is a smokeless tobacco similar to chewing tobacco. It rarely makes headlines. But it certainly did when the FDA authorized a brand of snuff to market its products as having a major health advantage over cigarettes. Could this be true? Is it safe to use snuff?

What did the FDA authorize as a health claim?

Here’s the approved language for Copenhagen Classic Snuff:

If you smoke, consider this: switching completely to this product from cigarettes reduces risk of lung cancer.

While the statement is true, this FDA action — and the marketing that’s likely to follow — might suggest snuff is a safe product. It’s not. Let’s talk about the rest of the story.

What is snuff, anyway?

Snuff is a form of tobacco that’s finely ground. There are two types:

• Moist snuff. Users place a pinch or a pouch of tobacco behind their upper or lower lips or between their cheek and gum. They must repeatedly spit out or swallow the tobacco juice that accumulates. After a few minutes, they remove or spit out the tobacco as well. This recent FDA action applies to a brand of moist snuff.
• Dry snuff. This type is snorted (inhaled through the nose) and is less common in the US.

Both types are available in an array of scents and flavors. Users absorb nicotine and other chemicals into the bloodstream through the lining of the mouth. Blood levels of nicotine are similar between smokers and snuff users. But nicotine stays in the blood for a longer time with snuff users.

Why is snuff popular?

According to CDC statistics, 5.7 million adults in the US regularly use smokeless tobacco products — that’s about 2% of the adult population. A similar percentage (1.6%) of high school students use it as well. That’s despite restrictions on youth marketing and sales.

What accounts for its popularity?

• Snuff may be allowed in places that prohibit smoking.
• It tends to cost less than cigarettes: $300 to $1,000 a year versus several thousand dollars a year paid by some smokers.
• It doesn’t require inhaling smoke into the lungs, or exposing others to secondhand smoke.
• Snuff is safer than cigarettes in at least one way — it is less likely to cause lung cancer.
• It may help some cigarette smokers quit.

The serious health risks of snuff

While the risk of lung cancer is lower compared with cigarettes, snuff has plenty of other health risks, including

• higher risk of cancers of the mouth (such as the tongue, gums, and cheek), esophagus, and pancreas
• higher risk of heart disease and stroke
• harm to the developing teenage brain
• dental problems, such as discoloration of teeth, gum disease, tooth damage, bone loss around the teeth, tooth loosening or loss
• higher risk of premature birth and stillbirth among pregnant users.

And because nicotine is addictive, using any tobacco product can quickly become a habit that’s hard to break.

There are also the “ick” factors: bad breath and having to repeatedly spit out tobacco juice.

Could this new marketing message about snuff save lives?

Perhaps, if many smokers switch to snuff and give up smoking. That could reduce the number of people who develop smoking-related lung cancer. It might even reduce harms related to secondhand smoke.

But it’s also possible the new marketing message will attract nonsmokers, including teens, who weren’t previously using snuff. A bigger market for snuff products might boost health risks for many people, rather than lowering them.

The new FDA action is approved for a five-year period, and the company must monitor its impact. Is snuff an effective way to help smokers quit? Is a lower rate of lung cancer canceled out by a rise in other health risks? We don’t know yet. If the new evidence shows more overall health risks than benefits for snuff users compared with smokers, this new marketing authorization may be reversed.

The bottom line

If you smoke, concerns you have about lung cancer or other smoking-related health problems are justified. But snuff should not be the first choice to help break the smoking habit. Commit to quit using safer options that don’t involve tobacco, such as nicotine gum or patches, counseling, and medications.

While the FDA’s decision generated news headlines that framed snuff as safer than smoking, it’s important to note that the FDA did not endorse the use of snuff — or even suggest that snuff is a safe product. Whether smoked or smokeless, tobacco creates enormous health burdens and suffering. Clearly, it’s best not to use any tobacco product.

Until we have a better understanding of its impact, I think any new marketing of this sort should also make clear that using snuff comes with other important health risks — even if lung cancer isn’t the biggest one.

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