TIME public health

You Asked: Should I Use Antibacterial Soap?

Illustration by Peter Oumanski for TIME
Illustration by Peter Oumanski for TIME

Research shows they offer zero health benefits. But by changing the makeup of your skin and body bacteria, antibacterials may be fostering new health concerns—especially for kids.

Whoever said “cleanliness is next to godliness” would think pretty highly of modern-day America. Never before has a population so committed itself to rubbing, scrubbing, sterilizing and disinfecting itself from the grit and grime of the natural world. And for good reason: global trade and travel have allowed viruses to hop from country to country via innocent workers and tourists.

But while our zeal for cleaning is well-intentioned, our efforts are often misguided. In the case of antibacterials, we may be doing ourselves harm.

“Somehow, through marketing or misinformation, we’ve been led to believe that if we get rid of bacteria, we’ll improve our lives and our health,” says Dr. Martin Blaser, director of the Human Microbiome Program at New York University and author of Missing Microbes: How the Overuse of Antibiotics Is Fueling Our Modern Plagues. “In fact the opposite is probably true.”

Microbiologists are fond of pointing out that your body contains more bacteria than anything else; microorganisms populate your skin and gut by the trillions. “We live in a bacterial world,” Blaser says. “And the vast majority of those bacteria are neutral or beneficial. Very few are harmful.”

MORE: Antibiotics Overload Is Endangering Our Children

While much of his research has focused on the dangers associated with antibiotic drugs, Blaser is also concerned about the use of bacteria-killers in the home, especially where infants and children are concerned. “Early life is a critical time to build immunity and metabolism and cognition,” he says. “There’s more and more evidence that bacteria are a part of that development.” Remove some bacteria, and its possible you could be upsetting or altering that development in unpredictable ways.

There could be other consequences. “We’re seeing a greater number of antibiotic-resistant microorganisms over the periods these products have been around,” says Dr. Allison Aiello, an epidemiologist at the Gillings School of Public Health at the University of North Carolina. Aiello says there are known factors, such as antibiotic use in humans and animals, that have led to this uptick. But antimicrobial soaps containing triclosan may also be contributing to the appearance of these heartier organisms outside of healthcare settings, she says.

MORE: Antibiotic-Resistant Bacteria Are Now In Every Part of the World

At this point, there are still many gaps in the data on anti-microbial chemicals. But Aiello says various forms of triclosan—the chemical found in antibacterial hand soaps and body washes—may actually encourage the spread and strength of some bacteria by killing off others. She says there’s also some concern these chemicals may interact with human hormones in damaging ways. Those concerns led the state of Minnesota to ban triclosan from cleaning and personal care products.

“The potential risks definitely outweigh the benefits, which are none,” Aiello says.

You read that right. To date there is no evidence that washing and scrubbing your body and home with antibacterial products does any good.

One study split 1,000 households into two groups. While one of those groups received antibacterial cleaning products, the other got plain soap. Neither the researchers nor the participants knew which type of cleaner they were using.

“In terms of infection rates and sickness, we found absolutely no difference between antibacterial soap and regular soap,” says Dr. Elaine Larson, first author of that household study and director of the Center for Interdisciplinary Research on Antimicrobial Resistance at Columbia University.

Larson—working with Aiello—has reviewed dozens more research efforts that looked into the efficacy of antibacterials. Again, she and her colleagues found no benefit.

This doesn’t mean cleaning is unimportant, she says. Rather, the mechanical force—the act of rubbing your hands together under hot water, or scrubbing a cutting board with a brush—is what dislodges and cleans away harmful microbes; “The idea that soap kills germs is a misconception,” she says. “Soap just helps you wash germs off.” Regardless of the type of soap you’re using, Larson says “the rub is more important.”

Of course, there are times when true sanitization is necessary, Larson says. A doctor performing surgery is one of those times. People who have weakened immune systems may also require special consideration. But even in those circumstances, Larson says an alcohol-based sanitizer—not antibacterial soap—is needed to wipe out potentially harmful germs.

“This mythology has developed that we can sterilize the world, and that that’s a good thing,” Blaser says. “But the question should be, what’s the benefit? With many antibacterials, there isn’t one.”

TIME Research

You Asked: Are the Honeybees Still Disappearing?

You Asked: Are Honeybees Still Disappearing?
Illustration by Peter Oumanski for TIME

Beekeepers continue to grapple with historically high death rates. And now something’s up with the queens.

From almonds to cherries, dozens of food crops are partially or totally dependent on honeybee pollination. And while media attention has waned, there’s still reason to worry about the country’s smallest and most indispensable farm workers.

Bee researchers first reported massive die-offs back in the 1990s. But the plight of the honeybee didn’t truly buzz into the national consciousness until the spring of 2013, when data revealed the average beekeeper had lost 45% of her colonies the previous winter. A mysterious phenomenon known as colony collapse disorder (CCD) further stoked the fires of public interest.

Jump to 2015. While last winter’s bee death data won’t be published for a few more weeks, things appear to be “status quo,” says Dr. Greg Hunt, a honeybee expert at Purdue University. Unfortunately, the status quo is grim. “We’ve been seeing about 30% loss in an average winter,” Hunt says. “The winter before last was particularly bad and got a lot of attention, but things have been bad for a while.”

Dr. Dennis vanEngelsdorp—a University of Maryland entomologist who helps collect and publish the winter death data each spring—says there are three “primary drivers” of honeybee loss: The varroa mite, pesticides and poor nutrition. He doesn’t hesitate when asked to name the largest threat to bees: “I’d get rid of the varroa first.”

Varroa mites, properly (and frighteningly) named Varroa destructor, likely migrated to the U.S. sometime in the 1980s. They attach to a honeybee’s body and suck its blood, which kills many bees and spreads disease to others. The varroa can jump from one colony to another, wiping out whole populations of honeybees, vanEngelsdorp explains. There are treatments that combat the varroa. But many small-scale beekeepers don’t use them. “That’s bad, because they can spread mites to neighboring colonies,” he adds.

Of the two other major bee-killers vanEngelsdorp listed, pesticides have arguably gotten the most press—especially a commonly used category called neonicotinoids. While considered safe for humans, research suggests neonicotinoids may be extremely harmful to bees and many other insects, and so have been banned in some European countries. But the amount these chemicals contribute to bee deaths and colony collapse disorder is still debated. “We don’t find levels of neonicotinoids that are indicative of widespread exposure or harm,” vanEngelsdorp says.

The third problem—poor nutrition—is likely the most confounding of the honeybee’s enemies.

“Bees need a varied diet of different pollens in order to grow into strong, healthy workers,” explains Dr. Heather Mattila, a honeybee biologist at Wellesley College. Unfortunately, a country once filled with meadows of diverse, pollen-packed wildflowers is now blanketed by crops, manicured lawns, and mown fields barren of pollen sources. “A green space can be a green desert if it doesn’t have flowering plants that are bee-friendly,” Mattila adds.

Combine a restricted diet with environmental factors like extremely cold winters and scorching summers, and stressed honeybee colonies are less able to resist the ravages of mites, pesticides, viruses and other potential causes of colony collapse disorder.

To fill nutrition gaps, beekeepers give their wares pollen supplements. Along with tactics like colony splitting, keepers can restore their bee supplies quickly during the spring and summer months. But Hunt says the cost to do this is large—and growing larger. “As long as beekeepers are willing to put more money and hard labor into it, we can come back and rebuild our colonies and numbers,” he explains. “But whether this is all sustainable is an open question.”

Mattila calls this a “Band-Aid,” not a cure. “I think we’re making the best of a tough situation,” she says. Both she and Hunt applaud companies and localities that have started letting wildflowers grow along the sides of highways or under rural power lines—places that used to be mown and sprayed with herbicide. The federal government has also taken steps to protect lands that offer honeybees (and lots of other insects) the sustenance they need. Mattila says every American can help these efforts by planting flowers and avoiding chemical treatments.

But she mentions another emerging concern when it comes to the future of America’s honeybees: The strange, abrupt deaths of many bee queens. “When I started working with bees 18 years ago, we’d replace living queens every two years,” she recalls. “Now queens die after half a summer. Nobody is really clear on why.”

The “Band-Aid” she mentioned might already be coming off.

Read next: You Asked: Do Fruit Flies Come From Inside Fruit?

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TIME medicine

You Asked: Why Is My Hair Falling Out?

You Asked: Why Is My Hair Falling Out?
Illustration by Peter Oumanski for TIME

Drugs can help. But a lasting solution might require lifestyle changes.

First, let’s debunk a few myths: Shampooing, brushing and towel drying your hair aren’t making it fall out. “People associate these things with hair loss because they see the hair come away. But these aren’t the cause,” says Dr. Melissa Piliang, a dermatologist with the Cleveland Clinic. In fact, Piliang says shampooing less frequently may make things worse. “It can lead to dandruff and scalp inflammation, which can exacerbate hair loss,” she says.

Hats and ponytails also get a bum rap. “If a ponytail is worn so tightly it pulls on your eyes, that could damage your hair and lead to breakage,” Piliang acknowledges, adding that tight braiding, extensions and weaves—which yank on small groups of hair follicles—can also cause problems. “But generally wearing a ponytail or a hat won’t cause hair loss,” she says.

Men and women lose their hair for different and interrelated reasons, ranging from genetic factors to a poor diet, says Dr. Adam Friedman, director of dermatologic research at the Montefiore-Albert Einstein College of Medicine in New York. “It’s rare for hair loss to be caused by just one thing,” he says.

To understand these causes, it’s helpful to know how your hair works. Similar to the way your skin’s cells turn over, your hair is constantly sprouting, growing and falling out. Guys with healthy hair shed between 60 to 80 follicles a day, while women lose roughly 100, Friedman says.

When it comes to male- and female-pattern baldness—the most common types of hair loss—certain hairs grow in shorter and shorter over time, and eventually stop growing back at all. This is usually the result of a genetic sensitivity to hormones in the skin, Friedman says. “In men, you see this most in the front and sides of the scalp,” he explains. “In women, it’s more centrally located and diffuse.” Friedman says this is a slow process, one that can take years to become apparent.

For these people, drugs that block the production of skin hormones or keep hairs from falling out—such as minoxidil and finasteride—tend to work well, Friedman says. But both are better at stopping hair loss than they are at regrowing hair. “If you’re bald and want treatment, there’s often not much you can do,” he says. For this reason, it’s imperative that you see a doctor as soon as you notice a problem.

Poor nutrition is another potential contributing factor. Friedman says low levels of iron, vitamin D, some B vitamins and zinc have all been linked to hair loss. While typically not the main cause of your thinning mane, nutrient or vitamin deficiencies can make the problem worse, he says. Fixing your diet or taking supplements can help, but it’s often just one part of a multifaceted solution.

If clumps come out when you shower or you notice thinning in just a few weeks or months, you’re more likely dealing with another common condition called acute telogen effluvium, Piliang says. This rapid hair loss is basically a short-term ramping up of your hair’s normal shedding process.

Any event that puts a lot of stress on your body—like childbirth, surgery or rapid weight loss—can result in this alarming, clumpy hair loss, which tends to start a couple months after the event, Piliang says. The shedding can last for six months and may result in your losing up to 70% of your hair. But typically the hair grows back, she explains.

There are many more explanations for hair loss, including scalp infections, inflammatory diseases like alopecia areata, or systemic diseases like lupus. Treatments vary widely and may include a combination of oral or topical drugs, light therapy, dietary changes, and stress-reducing interventions. You really need an expert’s help to assemble all the puzzle pieces, says Dr. Laurel Schwartz, a dermatologist in private practice at the Philadelphia Institute of Dermatology.

If you’re experiencing skin irritation, redness, scaling or pain, Schwartz recommends seeing someone ASAP to head off risks like permanent hair loss and scarring.

More good advice: Stay away from “miracle” cures marketed online or in late-night TV infomercials. They’re not the answer. “Hair loss is such an emotionally charged experience,” Schwartz says. “And when you’re really upset, you’re willing to try anything.” Time spent experimenting with different over-the-counter or infomercial products is often time (and money) wasted.

Your hair can offer a glimpse of what’s going on in the rest of the body, Schwartz says. “If you notice a problem, discuss it with a doctor to determine the ultimate cause.”

TIME public health

You Asked: Why Do My Boobs Hurt?

You Asked: Why Do My Boobs Hurt?
Illustration by Peter Oumanski for TIME

Most of the time, blame hormones.

From a dull ache to a sharp stab, breasts hurt in a hundred different ways for a hundred different reasons. For many women, those myriad aches and stabs are the results of normal, healthy hormone fluctuations related to their menstrual cycles.

“Pain is most common during that period of a woman’s cycle just before she menstruates, when hormones like estrogen and progesterone peak,” says Karthik Ghosh, MD, director of the breast clinic at Mayo Clinic in Rochester, Minnesota.

You probably already knew that. But when your hormones go haywire, why do your breasts feel beat up? Rising estrogen levels stimulate the breasts’ milk ducts, while spiking progesterone does the same to a woman’s milk glands. Both can result in swelling and pain. Progesterone also causes fluid retention, which can lead to a feeling of heaviness or tenderness, Ghosh says.

With the onset of menstruation, levels of those hormones drop off, Ghosh says. For that reason, breast pain or tenderness tends to subside as soon as a woman starts her period. Because oral contraceptives iron out those hormonal peaks and valleys, women on birth control often don’t experience this monthly ebb and flow of aching. (But when women first start a contraceptive like the pill, some pain is common.)

Many women also experience cysts, which result when pockets of fluid form within the ducts of the breast. These cysts can sometimes be painful, says Dr. Susan Harvey, director of the Johns Hopkins Breast Imaging Section.

Young women in puberty, pregnant women and older women nearing menopause may all experience breast pain due to hormone fluctuations, says Dr. Bonmyong Lee, Harvey’s colleague and an assistant professor of radiology at Johns Hopkins. Particularly during the early stages of menopause, women who may have never had pain or cysts may suddenly start to experience both, Lee says.

Apart from these hormone-related issues, Ghosh says anything that causes chest wall muscle soreness—like starting a new workout—can cause what’s called secondary pain in the breasts. So can a common type of inflammation, called costochondritus, which affects the place where a woman’s ribs and sternum come together. Even an unsupportive brassiere can allow the breasts to pull on the chest wall, leading to pain, Ghosh says.

One condition that tends not to cause pain is cancer. For women who may notice a lump that is sensitive or painful, it’s more likely a benign cyst, Ghosh says. Still, she recommends seeing a doctor if you find a lump, painful or otherwise.

There are several less common or unproven causes of breast pain, from infection to caffeine consumption. So how can you determine whether to worry or brush it off? If the pain is concentrated in one part of your breast and doesn’t subside after a few weeks, see someone, Harvey says. You should also visit a doctor if your skin is flushed or red, which may be a sign of an infection.

“There’s no golden rule when it comes to identifying specific types of breast pain,” Ghosh says. “If it worries you or seems out of the ordinary, see a doctor.”

Read next: Should I Dry Brush My Skin?

 

TIME toxins

You Asked: Should I Dry Brush My Skin?

Illustration by Peter Oumanski for TIME

There may be benefits, but reducing cellulite isn’t one of them.

If you’re wondering what dry brushing is, the practice is exactly what it sounds like: Running a dry, soft-bristle brush over your bare skin. Methodologies vary, but most practitioners and beauty blogs recommend brushing your limbs and torso, always motioning toward your heart. Do this for a few minutes every day, they say, and you’ll increase blood flow and circulation, which will help your body and lymphatic system clear away toxins. Dry brushing is also thought to reduce cellulite and exfoliate, leaving your skin softer, more toned and better hydrated.

Unfortunately, there’s not much research to back up these health claims. “I know dry brushing is popular, but the actual benefits are unclear,” says Dr. Tina Alster, director of the Washington Institute of Dermatologic Laser Surgery and a clinical professor at Georgetown University.

Alster says that rubbing the skin—with a brush, your hand or anything else—will increase blood flow and circulation, giving your skin a flushed, youthful and “slightly swollen” appearance. (The same thing happens if you pinch your cheeks.) But your skin will return to normal very quickly after you’ve stopped brushing it, Alster says. There’s no evidence this temporary surge in blood flow will help your body remove waste or toxins, she adds.

Dry brushing will clear away dead skin cells. But exfoliating isn’t necessary for those in their teens and twenties. “When you’re young, your skin’s outermost layer will automatically turn over without any mechanical help,” Alster explains. Beginning in your thirties and increasing as you age, Alster says your skin’s cells can grow “stickier,” which can lead to accumulation and a dull appearance. “Exfoliation can help remove those stuck-together cells,” she says. “But you want to do it very gently and infrequently, or you may do more harm than good.”

Brushing too frequently or vigorously—or using a brush with rough bristles—could cause “micro-cuts” in your skin that may lead to infection, Alster says. Exfoliating more than once a week could also break down your skin’s protective barriers, leaving your hide less hydrated and prone to irritation, says Dr. Marc Glashofer, a New York-based dermatologist and member of the American Academy of Dermatology. For that reason, Glashofer says people with eczema or dry skin should avoid dry brushing altogether.

Glashofer mentions a common skin condition called keratosis pilaris (KP), which consists of many small rough bumps that tend to show up on the backs of arms and thighs. Dry brushing these areas could theoretically be beneficial, he says, but there’s no evidence yet.

And when it comes to reducing cellulite, both Glashofer and Alster say there’s nothing to back up such claims. “If brushing the skin twice per day would eliminate cellulite, you would have heard a lot more about it and there’d be some scientific proof,” Glashofer says.

Of course, not everything that benefits your body is easily captured by medical research. From meditation to massage, many practices once dismissed by clinicians have recently been linked to meaningful psychological and physical benefits. It’s possible dry brushing may one day fall into this category, but that day hasn’t arrived yet.

“If you like dry brushing and your skin looks good, that’s fine,” Alster says. “But would I encourage it as a dermatologist? Definitely not.”

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TIME Mental Health/Psychology

You Asked: How Many Friends Do I Need?

You Asked: How Many Friends Do I Need?
Illustration by Peter Oumanski for TIME

Maybe just a handful, though quality trumps quantity.

Friends do your health so many favors. They protect your health as much as quitting smoking and a great deal more than exercising, according to a large 2010 review in the journal PLOS One. More research has shown that socially isolated people are more than twice as likely to die from heart disease as those with a solid social circle.

“Strong social relationships support mental health, and that ties into better immune function, reduced stress and less cardiovascular activation,” says Dr. Debra Umberson, a sociologist at the University of Texas, Austin. Umberson says emotional support is just one of a dozen ways friends may safeguard your health and extend your life.

MORE Here’s How Hugs Can Prevent the Flu

Unfortunately, though, many of us don’t have enough of them. According to data from the General Social Survey (GSS), the number of Americans who say they have no close friends has roughly tripled in recent decades. “Zero” is also the most common response when people are asked how many confidants they have, the GSS data show. And adult men seem to be especially bad at keeping and cultivating friendships.

That may seem strange in the era of Facebook, Twitter and boundless digital connectivity. But the “friends” orbiting at the farthest reaches of your digital galaxy aren’t the ones that matter when it comes to your health and happiness.

The vital friendships—the pals you hug and laugh and lament with—are the ones who have the greatest impact on your health and happiness. You need between three and five of them for optimal wellbeing, suggests research from Dr. Robin Dunbar, an evolutionary psychologist at the University of Oxford.

Dunbar’s name comes up a lot when you start digging into the subject of friendship. From his early work studying the brains and social circles of primates, he recognized that the size of a human’s social network might be limited by the size of a certain part of the human brain called the neocortex, a critical site for higher brain functions. After some complicated study, he came up with a figure now known as “Dunbar’s number.”

That number—usually cited as 150, but actually a range between 100 and 200—is the approximate size of a person’s social circle, or the perpetually changing group of friends and family members that you would invite to a large party. While you may have far fewer than 150 of these people in your life, your brain really can’t hold a close connection with more than 150, Dunbar’s research shows. Within that group, he says your closest 15 relationships—including family members or “kin”—seem to be most crucial when it comes to your mental and physical health.

But that’s not to say a brother or sister offers you the same benefits as a close friend, Dunbar says. While your kin are more likely to be there for you when you need help, your good friends tend to fire up your nervous system and trigger the release of feel-good neuropeptides called endorphins. Whether you’re laughing with your pal or feeling him or her touch your shoulder in sympathy, the resulting rush of endorphins seems to “tune” up your immune system, protecting you from disease, Dunbar explains.

So yes, for the sake of your health, you need friends—ideally the really close kind you see face-to-face on a regular basis. But even one very good friend can improve your life in profound ways, says Dr. Mark Vernon, a philosopher, psychotherapist and author of The Meaning of Friendship.

Despite their value in terms of your health and wellbeing, don’t think of them as your personal social doctors. Vernon warns against turning your friends into what he calls “service providers”—that’s not what friendship should be about, he says, even if your pals are good for you.

In the end, Vernon says Ralph Waldo Emerson may have offered the best advice when it comes to making and keeping close pals: “The only way to have a friend is to be one.”

Read next: 5 Types of Friends That Everyone Has

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TIME Exercise/Fitness

You Asked: Should I Do The Insanity Workout?

Illustration by Peter Oumanski for TIME

Expect results—though maybe not the ones you’d hoped for.

The name alone is a challenge—a dare. You’d have to be insane to attempt this workout. Of course, that’s a big part of the appeal. If the exercise is “extreme” or “crazy,” you assume the body benefits will be dramatic. And they may be—just not in the ways you’d expect from checking out the workout’s promotional materials, which emphasize weight loss.

While it’s continually changing, the latest iteration of “INSANITY” is a 60-day program composed of 30-minute bouts of very high-intensity aerobic and resistance exercise, to be completed six days a week. While research has linked physical fitness gains to Insanity-style interval workouts, the evidence that these programs lead to weight loss is anything but rock solid.

“We’ve shown that when it comes to cardiovascular fitness and function, greater intensity leads to greater adaptations,” says Todd Astorino, PhD, associate professor in the department of kinesiology at California State University, San Marcos.

Astorino has studied the health and fitness effects of very rigorous bouts of interval training, often referred to as high-intensity interval training (HIIT). He says there’s little doubt your athletic condition—the ability of your heart and lungs to handle physical activity—would improve if you completed something along the lines of an Insanity workout. He also says your blood sugar levels would likely drop, a change that could help protect you from metabolic diseases like type-2 diabetes. Throw in the body-resistance component of Insanity workouts, and you’ll certainly grow stronger too.

What about weight loss? “The research is very mixed, especially in the long term,” Astorino says. “I think it would help you avoid weight gain. But that’s not the same as losing weight.”

Hundreds of studies have looked into the effect of regular exercise on body weight. While physical activity is unquestionably good for your health, exercise alone doesn’t have a huge impact on the number you see on your bathroom scale, concludes one recent study appearing in the journal Obesity Reviews.

MORE You Asked: Why Are People Addicted To CrossFit?

Another study, this one from Stephen Boutcher, PhD, associate professor at Australia’s University of New South Wales, specifically examined the effect of Insanity-style HIIT training on body fat. Boutcher’s research found “significant” fat reduction—or a little more than 4 pounds of lost body fat after three months of training. That’s significant in science terms, but probably not what you’re expecting when starting a workout program that highlights happy customers who have lost 40, 50, or even 90 pounds.

Boutcher says there’s some evidence HIIT training may help suppress appetite in ways traditional aerobic exercise doesn’t. But to shed lots of weight—the kind of “total-body” transformation you see in product testimonials—you also have to eat a healthy diet, the research suggests. (Read the fine print on the INSANITY website, and you’ll find analogous disclaimers stating a “proper diet” is necessary to achieve and maintain weight loss.)

But for some people, even regular exercise and an improved diet won’t dramatically change the way their bodies look. “Many people are just naturally bigger,” Astorino says. “For them, trying to look physically lean would probably require some very dramatic diet restrictions.”

Of course, none of this touches on the psychological perks of challenging yourself with a butt-whipping exercise regimen. Talk to someone who has run a marathon or finished an Insanity program, and you can hear the sense of accomplishment and pride they feel when they talk about their achievement.

“If you can get through something like this, you’ll have confidence and a good understanding of what your body can tolerate,” Astorino says. Those benefits, along with improved endurance and metabolic health, are nothing to scoff at. But if you’re expecting to transform your body and drop several sizes with INSANITY, the results might not be as crazy as you’d hoped.

Read next: A Workout You Can Do Anywhere

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TIME Apple

How Apple’s New Health App Could Be Used — or Abused

Apple CEO Tim Cook speaks on stage during an Apple special event at the Yerba Buena Center for the Arts on March 9, 2015 in San Francisco.
Stephen Lam—Getty Images Apple CEO Tim Cook speaks on stage during an Apple special event at the Yerba Buena Center for the Arts on March 9, 2015 in San Francisco.

"There are some things you can't figure out by someone tapping into an iPhone”

The biggest news at Monday’s Apple event was the launch of the much anticipated Apple Watch. But the company also announced a new type of software — ResearchKit — that it says will help medical researchers collect health data directly from patients via their various iDevices.

ResearchKit is a software “framework” that hospitals and other health care organizations can use to create diagnostic applications, said Jeff Williams, Apple’s senior VP of operations, at the watch event. An example: Williams demonstrated one app called mPower, designed to measure hand and voice tremors related to Parkinson’s disease.

“With the use of this technology, we feel there’s an unprecedented opportunity to gain insight into what it’s like to live with Parkinson’s 24 hours a day, seven days a week,” says Dr. Todd Sherer, CEO of the Michael J. Fox Foundation for Parkinson’s Research. The foundation collaborated with Sage Bionetworks to help develop the Parkinson’s app featured at Apple’s event. Fox’s foundation has also announced a new data-collection initiative, Fox Insight, which Sherer says his organization hopes to soon pair with the mPower app.

Sherer said identifying qualified patients for clinical trials and other research efforts is another potential benefit of this new technology. “Getting people to participate in clinic-based trials is a challenge for many disease researchers, including those studying Parkinson’s,” he says.

Apple’s Williams mentioned other applications — now available — that can help spot symptoms of diabetes, heart disease and asthma. Williams said these apps were developed with the help of Massachusetts General Hospital, Stanford University, the Dana-Farber Cancer Institute, and other equally august health care organizations.

Apple’s Williams was adamant that any health information you share through ResearchKit will remain confidential. “You choose what studies you want to join, you are in control of what information you provide to which apps,” states information appearing on the Apple site.

While helping health care providers and researchers collect data and recruit qualified participants could lead to meaningful research advancements, some see reasons to be wary. “Two things concern me,” says Dr. David Ross Camidge, director of the Thoracic Oncology Clinical Program at the University of Colorado Cancer Center. For starters, big-name institutions may have more money and resources to develop these sorts of diagnostic apps, Camidge says. He worries patients may be directed away from the most-relevant or appropriate clinical trials to those that have the most funding behind them. “I certainly don’t know if that will be the case, but there seems like room for potential bias and commercialization,” he says.

Also, people tend to be lousy at self-reporting health-related information, Camidge says. A poorly designed app may generate misleading or contradictory patient data that could hinder instead of help the forward progress of some medical research. “I’m sure there are ways it will be very useful,” he adds. But he adds that some things are not so simplistic, cautioning that for conditions like cancer, Alzheimer’s and multiple sclerosis, he says, “There are some things you can’t figure out by someone tapping into an iPhone.”

TIME Diet/Nutrition

Why Full-Fat Dairy May Be Healthier Than Low-Fat

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Danny Kim for TIME

Dodging dairy fat may be bad for your waistline

Skim milk or whole? Non-fat yogurt or full-fat? For decades, public health officials have treated these decisions as no-brainers. Cut the dairy fat, they’ve maintained, and you’ll sidestep calories without missing out on good stuff like calcium and protein. Win-win. But they might have been wrong, a chorus of experts now say.

A recent review published in the European Journal of Nutrition of the existing research on dairy fat came to some surprising conclusions: People who eat full-fat dairy are no more likely to develop cardiovascular disease and type 2 diabetes than people who stick to low-fat dairy. When it comes to weight gain, full-fat dairy may actually be better for you, the review found.

“In terms of obesity, we found no support for the notion that low-fat dairy is healthier,” says Dr. Mario Kratz, first author of the review and a nutrition scientist at the Fred Hutchinson Cancer Research Center in Seattle. Of the 25 studies included in his team’s review, Kratz says 18 reported lower body weights, less weight gain, or a lower risk for obesity among full-fat dairy eaters. The other seven studies were inconclusive. “None of the research suggested low-fat dairy is better,” he says.

More research supports his team’s findings. A 2013 study in the Scandinavian Journal of Primary Health Care tracked the dairy intake and obesity rates of more than 1,500 middle-aged and older adults. Those who frequently ate full-fat butter, milk, and cream had lower obesity rates than those who eschewed dairy fat. “Based on my own research and on the research of others, I believe high-fat dairy is less likely to contribute to obesity that low-fat dairy,” says Dr. Sara Holmberg, first author of the study.

The belief that fat isn’t a health villain has been gaining traction the last few years, especially as data has piled up showing that low-fat diets don’t work. And while national health organizations seem to be softening their stance on fat, they still recommend reaching for low- or non-fat dairy at the supermarket.

Their justification: “Research has shown consistently that nutrient-rich foods—that is, foods that pack a lot of micronutrients into every calorie—are healthier,” says Isabel Maples, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. Maples says reduced-fat dairy provides calcium, potassium, and other good things Americans need in their diet, and does so with fewer calories than full-fat dairy. She says reduced-fat dairy also contains less saturated fat.

Kratz doesn’t disagree with Maples’s comments. But he says they make assumptions about dairy that aren’t backed up by existing evidence. “Data should be weighed more heavily than assumptions,” he says. “And the data don’t support the notion that eating full-fat dairy is worse for your health than reduced-fat or non-fat dairy.”

How could something with more calories be better for your waistline? Some researchers argue that not all calories are equal—especially when it comes to weight gain. Also, focusing on calories-per-serving largely ignores a mammoth factor when it comes to obesity: fullness. Kratz says the fatty acids that are stripped out of reduced-fat dairy may help you feel full sooner and stay full longer—meaning you’ll eat less now and in the coming hours.

Dairy’s fatty acids may also play a role in gene expression and hormone regulation. In simple terms, these acids may crank up how much energy your body burns, or limit the amount of fat your body stores. “We don’t know any of these things for certain,” Kratz adds. “But they could help explain why our findings show full-fat dairy consumption is preferable to low-fat when it comes to a person’s risk for obesity.”

Holmberg, the author of the Scandinavian study, calls dairy “paradoxical,” and says it’s not possible to judge dairy’s health effects based only on its macronutrient content. “It is important to study the effect of real food and not just nutrients,” she adds.

Several more European studies have suggested similar links between full-fat dairy and lower rates of obesity, heart disease, and diabetes. And a just-published review from the journal BMJ concludes that, back in the 1970s—when health regulators established national diet guidelines that encouraged people to avoid fat—there wasn’t evidence to support those warnings. Basically, the foundation for all your “fat is evil” beliefs may have always been weak.

At the same time, none of this means you should gorge yourself on full-fat dairy. “We shouldn’t swing the pendulum too far in the other direction and say, ‘Put butter in everything and eat as much dairy as you want,’ ” Kratz warns. (Compared to many foods—especially vegetables and fruit—dairy contains no fiber, which is critical for digestion, for how the body manages sugar, and which plays an important role in maintaining a healthy weight.)

But if you’re deciding between skim milk and whole milk, the existing research argues you may be better off grabbing the full-fat stuff.

TIME Diet/Nutrition

You Asked: Why Can’t I Eat Raw Meat?

Illustration by Peter Oumanski for TIME

Well, you could. But you’d be rolling the dice.

Sushi restaurants are nearly as rampant as Starbucks stores. So why is raw fish okay to consume, while raw beef, pork and other land animals are typically not on the menu?

For one thing, the parasites and bacteria that set up shop in raw animal meat are different and more dangerous than the ones you’d find in raw fish, says Dr. Robert Tauxe, deputy director of the Division of Foodborne, Waterborne and Environmental Diseases within the Centers for Disease Control and Prevention (CDC).

From salmonella and parasitic E. coli to worms, flukes, and the virus hepatitis E, Tauxe says the creepy crawlies that may inhabit raw meat tend to be more harmful to humans than the microorganisms you’d find in raw fish. “Perhaps it’s because our bodies are more closely related to land animals than to those of fish,” he explains.

The way animals are slaughtered and packaged also has a lot to do with their health risks, says Dr. Eugene Muller, a microbiologist at Framingham State University in Massachusetts. “Parasites and bacteria tend to come from an animal’s gut, not its muscle,” he says. If your butcher nicks open an animal’s intestines, any harmful microorganisms released could contaminate all the meat the butcher is preparing.

Packaged ground beef is particularly likely to house sickness-causing bacteria or parasites, says Dr. Lee-Ann Jaykus, professor of food science at North Carolina State University. That’s because a single package of ground beef could contain meat from dozens of cows, Jaykus says. “One contaminated animal could corrupt dozens of batches,” she explains. For that reason, she advises never eating hamburger that’s red or rare in the center.

Both Muller and Jaykus say whole cuts of beef are less risky because they come from a single animal. “Anything harmful lives on the surface of the meat, not inside the muscle,” Muller says. “So if you like your steak very rare, just searing the outside will likely kill anything harmful.”

Jaykus agrees, but says you have to watch out for something called “mechanically tenderized meat,” which involves puncturing the beef with small needles or blades to make it more tender. She says many restaurants and grocery stores sell meat that’s undergone this process because it improves the texture of cheaper cuts like sirloin or round. “This process can force contaminants into the muscle tissue where searing the outside won’t kill them,” she says. “You don’t see this at high-end steakhouses, but it’s an issue with steaks purchased for home cooking and in some restaurants.”

Most of these concerns and caveats also apply to lamb, pigs, chickens and other land animals—though Muller says pigs and chickens tend to carry some harmful microorganisms you don’t find in cows or sheep. “But I don’t think many people really want to consume raw pig or raw chicken,” he adds.

Fish is a different story. Setting aside the differences between fish and mammals when it comes to the number, type, and frequency of potentially dangerous organisms they may harbor, fish tends not to be ground or mixed. That lowers the likelihood of a single disease-carrying salmon or tuna contaminating others, Jaykus says.

Also, any raw fish you consume at a sushi restaurant are caught in colder waters and frozen before you eat them. “This kills the encysted worms and other parasites,” Tauxe says. Unfortunately, freezing doesn’t kill parasitic E. coli and many of the harmful microorganisms you’d find in meat, Muller says.

With raw fish, oysters and other uncooked seafood, you’re taking a risk, Muller says—though not nearly as big a risk as eating that bloody tenderloin or tartare.

Read next: The 50 Healthiest Foods of All Time (With Recipes)

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