Patti Neighmond

It's been clear for many years that vitamin D helps keep bones strong, but studies have been inconclusive and conflicting about the vitamin's value in protecting against certain cancers, including colorectal cancer.

Colorectal cancer is the second-leading cause of cancer death in the United States, most frequently diagnosed among adults over 65. To catch those typically slow-growing malignancies early, when they can often be cured, most doctors' groups recommend colorectal cancer screening starting at age 50.

But the American Cancer Society this week changed its advice and is recommending that screening start five years earlier.

Though Americans spend an estimated $80 billion to $100 billion each year in hopes of easing their aching backs, the evidence is mounting that many pricey standard treatments — including surgery and spinal injections — are often ineffective and can even worsen and prolong the problem.

Research has shown that sharp reductions in the amount of food consumed can help fish, rats and monkeys live longer. But there have been very few studies in humans.

Now, some researchers have found that when people severely cut calories, they can slow their metabolism and possibly the aging process.

Eventually it happens to everyone. As we age, even if we're healthy, the heart becomes less flexible, more stiff and just isn't as efficient in processing oxygen as it used to be. In most people the first signs show up in the 50s or early 60s. And among people who don't exercise, the underlying changes can start even sooner.

After Virginia Harrod was diagnosed with stage 3 breast cancer in 2014, she had a double mastectomy. Surgeons also removed 16 lymph nodes from under her armpit and the area around her breast, to see how far the cancer had spread and to determine what further treatment might be needed. Then she underwent radiation therapy.

Marian Smith somehow missed getting a flu shot this year, which is unlike her — in the past, she always got one.

The 58-year-old Washington D.C. resident says it was easier to remember to get it when the vaccine was provided at a clinic at work. But now the clinic is a bus ride away, and getting the shot wasn't at the top of her mind.

"Of course, I could get it right here at the grocery store," Smith tells NPR, as she rushes to pick up her lunch. "But I just didn't get it — I don't know, I can't tell you why."

Kids who vape and use other forms of e-cigarettes are likely to try more harmful tobacco products like regular cigarettes, but e-cigarettes do hold some promise for helping adults quit.

That's according to the National Academies of Science, Engineering and Medicine, which published a comprehensive public health review of more than 800 studies on e-cigarettes on Tuesday.

With the death of biologist Mathilde Krim on Monday, at the age of 91 at her home in New York, the world lost a pioneering scientist, activist and fundraiser in AIDS research. She is being widely praised this week for her clarity, compassion and leadership.

Amid the panic, confusion and discrimination of the HIV epidemic's earliest days, Krim stood out — using science and straight talk, in the 1980s and beyond, to dispel fear, stigma, and misinformation among politicians and the public.

Where you live — in a city versus a rural area — could make a difference in how old you tend to be when you first have sex, what type of birth control you use and how many children you have.

These are the findings from federal data collected using the National Survey of Family Growth, which analyzed responses from in-person interviews with more than 10,000 U.S. women, ages 18 to 44, between 2011 and 2015.

Enough already with the activity trackers and fitness apps. They're so 2017. If you're tired of tech and of exercising solo and are ready to simplify your routine — maybe even join a group exercise class — you'll be in good company this new year.

Editor's Note: This encore story, originally published in September, seems especially relevant this week, as we all relax (aka sit! binge-watch! eat!) for the holidays.

Count the number of hours you sit each day. Be honest.

It's long been known that hormonal contraception, like any medicine, carries some risks. But doctors and women have hoped that the newer generations of low-dose contraceptive pills, IUDs and implants eliminated the breast cancer risk of earlier, higher-dose formulations.

Now a big study from Denmark suggests the elevated risk of getting breast cancer — while still very small for women in their teens, 20s and 30s – holds true for these low-dose methods, too.

As the months grow colder and darker, many people find themselves somewhat sadder and even depressed.

Bright light is sometimes used to help treat the symptoms of seasonal affective disorder, or SAD. Researchers are now testing light therapy to see if it also can help treat depression that's part of bipolar disorder.

Research investigating a popular form of surgery aimed at easing chronic shoulder pain doesn't fix the problem, a careful, placebo-controlled study suggests.

In the condition known as shoulder impingement, certain movements, such as reaching up to get something off a shelf, for example, or even scratching your own back, can be painful and get worse during a night of tossing and turning.

A study published Tuesday in the journal Clinical Psychological Science finds that increased time spent with popular electronic devices — whether a computer, cell phone or tablet — might have contributed to an uptick in symptoms of depression and suicidal thoughts over the last several years among teens, especially among girls.

For most people, buying a "fragrance-free" or "hypoallergenic" moisturizer that turns out to be neither might be frustrating, but not harmful. But for people with sensitive skin or conditions like eczema or psoriasis, it can be a big problem.

"I will start to itch and I have to get it off my body right away," says 62-year-old Kathryn Walter, who lives in Ann Arbor, Mich.

Walter has a severe case of eczema and chooses moisturizers that claim to be free of fragrance and allergy-causing additives. But more often than not, Walter ends up with a product that clearly isn't.

Ariana Marciano is adding to her collection of about 75 tattoos at Body Electric, a tattoo and piercing studio on trendy Melrose Avenue in Hollywood. "I think they're so cool and I think they're visually really nice to look at," she says. There's a ram's head, an elk, a green-and-peach praying mantis, a love bug and a moth. Today she's getting a ladybug.

"I love bugs," Marciano, 23, says. "I think they're kind of overlooked." In about 20 minutes, a small ladybug with dots on its back and a bit of rusty orange takes its place on her elbow.

Count the number of hours you sit each day. Be honest.

"If you commute an hour in the morning and hour after work — that's two hours, and if you sit at an eight-hour-a-day desk job that's 10," says epidemiologist Loretta DiPietro of the Milken Institute School of Public Health at George Washington University.

"Then you come home at, say, 6 p.m., eat dinner and crash into your recliner for another three to four hours," says DiPietro. "That's 13 to 14 hours of sitting."

Walk down the aisle of your local pharmacy or grocery store and you'll be bombarded by a dizzying array of bleaching products, from gels and strips to paint-on bleach.

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