It's time now for our science news roundup from Short Wave, NPR's science podcast. I'm joined by Regina Barber and Emily Kwong. Hi all.
REGINA BARBER, BYLINE: Hey, Juana.
SUMMERS: All right, so I know you guys have brought us three science stories that caught your attention this week. What is in the mix this time?
KWONG: Yeah. We have a new lead on why some people don't seem to get the flu.
BARBER: A study on how much vigorous exercise you really need.
KWONG: And how food fortification helps people around the world get their nutrients.
SUMMERS: OK, I want to start off with this flu story because I'm not a person who really gets the flu. I don't think I've actually ever had it before. What about you guys?
SUMMERS: I might have just jinxed myself.
KWONG: Good for you (laughter). The flu heard you.
BARBER: Like, message us next week.
SUMMERS: So it sounds like this story is kind of about people like me who...
SUMMERS: ...Don't get the flu. And so scientists seem to have a clue now as to why.
BARBER: Yeah. So scientists found a lot of this one small protein in the noses and mouths of people who reported never getting flu symptoms, and that seems likely to protect them from the flu virus. And this study was published in the journal PNAS.
SUMMERS: How'd they find this out?
KWONG: Yeah. Scientists found a special group of participants for this study, 19 health care workers - so 19 people who had a ton of close contact with sick patients but never once had flu-like symptoms themselves. These folks also had never had a flu vaccine in their lives.
BARBER: And guess who the first study participant was.
SUMMERS: OK. I'm not going to get this right. Was it the surgeon general?
BARBER: Nope, nope. It was one of the researchers' moms.
SUMMERS: (Laughter) I love that.
MARIAM FERRER GARCIA: I always tell her that she has a superpower.
BARBER: Mariam Ferrer Garcia is a virologist who worked on this study. She's based at the FISABIO Foundation in Spain, and she always wondered why her mom, who's this retired nurse, managed to never get the flu. So Mariam and her team collected mouthwash samples from healthy health care workers in search of a reason. And they found high levels of this protein called dermcidin. It seems to block the flu virus before it even gets into cells. But this is not what dermcidin was known for.
SUMMERS: OK. Hold up for a second. Scientists already knew that some people had this protein?
KWONG: Yes, dermcidin is found in human sweat, where it blocks bacteria and fungus from infecting our skin. But what scientists didn't know is that dermcidin is an antiviral too.
BARBER: Yeah. So compared to healthy people who have definitely had the flu before to these, like, flu-resistant health care workers, they had a much higher level of dermcidin in their saliva and nasal passageways.
SUMMERS: OK. Let me see if I understand this. So the amount of this protein is ramped up in some people even before a person is exposed to the flu?
KWONG: Yeah. Scientists don't know exactly why some people have different levels of dermcidin. But Mariam says that measuring the amount could help identify people who may be at risk for getting very sick from the flu and then making sure those folks get a flu vaccine for sure. Scientists also want to explore how to use dermcidin as an antiviral and as a preventative treatment.
BARBER: Like in a nasal spray or something?
KWONG: Yeah, a nasal spray or even eye drops with dermcidin that could protect someone.
KWONG: The researchers also found that dermcidin blocked measles, one of the viruses that cause the common cold, and multiple strains of the flu, including a strain that's already resistant to current antivirals.
SUMMERS: Interesting. All right. Let's move on to topic two, which is about vigorous exercise. You guys both know that I'm a runner, but sometimes it's more of a jog than a sprint. Is that OK?
BARBER: I almost only jog (laughter). But, Juana, if you're getting at least 15 to 20 minutes of this vigorous exercise a week, then, yeah, you're doing great.
KWONG: Yeah. Researchers discovered this by looking at survey data showing the exercise habits of over 96,000 people in the U.K. And they found that people who put in just a few minutes of vigorous exercise a day were less likely to develop serious conditions such as heart and kidney disease, Type II diabetes and dementia.
SUMMERS: OK. So I have questions for you guys. And the first one is this. What actually counts as vigorous exercise?
KWONG: It's a really good question, yeah. So do you have a heart rate monitor?
SUMMERS: I do. I've got a little heart rate monitor...
KWONG: Well, it depends on your age, but generally speaking, the American Heart Association defines vigorous exercise as your body reaching 70- to 85% of your max heart rate. It's different for different ages and health levels.
BARBER: I spoke to the lead researcher of this study, Minxue Shen, and he said that even small things could count as vigorous exercise, like going up the stairs quickly or carrying heavy groceries or short bursts of cycling or running, which is really a good reminder for people who can't do, like, a ton of cardio.
SUMMERS: And this was surprising to the scientists?
BARBER: It was, at least, to Minxue.
MINXUE SHEN: We are very surprised. We expected the higher intensity activity to be beneficial, but we were struck by how much more important intensity was than total volume.
KWONG: Because the American Heart Association suggests 75 minutes of vigorous exercise a week, and then along comes this study saying, maybe you don't need that much.
BARBER: And it's also worth noting that the American Heart Association says that you can alternatively do 150 minutes of moderate exercise. But this study suggests it's best to prioritize these short bursts of intensity during that workout.
SUMMERS: Interesting. What do people in the sports world, though, have to say about all of this?
BARBER: Yeah. So that's what I thought, too. And one expert I talked to wasn't that surprised. In fact, he says that during workouts...
ELI FRIEDMAN: If you look at, like, the collective time that people are actually engaged in that high intensity, it's not a lot.
BARBER: This is Dr. Eli Friedman from Cedars-Sinai in Los Angeles. He trains athletes, so he wasn't surprised, but he also wanted to caution that, even though vigorous exercise is important, he doesn't want people to be discouraged from doing less intense exercise. Any exercise is good. And that this study - it shows pushing yourself a little, even for a few seconds, can go a long way.
SUMMERS: OK. I'm going to keep that on the back of my head when I go to the gym tomorrow.
KWONG: Yeah. Let's go sprint after this...
BARBER: I literally sprinted for, like, 30 seconds after I did this story.
SUMMERS: All right. Last thing. Today, you've also brought us a report about food fortification, and I do not know what that is. Please help.
KWONG: Yeah. It is so technical sounding, but fortified foods are pretty common. You've probably had iodized salt in a salt shaker.
KWONG: That's fortified with iodine. There's bread fortified with folic acid and breakfast cereal fortified with iron.
SUMMERS: You're thinking of something like Wheaties?
BARBER: Yeah. I just ate fortified cereal this morning. It was, like, cinnamon Chex.
BARBER: And basically, fortified foods contain carefully calculated boosts of essential vitamins and minerals because billions of people around the world are not getting enough micronutrients. And over time, a micronutrient deficiency has serious health consequences.
MDUDUZI MBUYA: From susceptibility to disease to impaired growth and development for young children, especially.
KWONG: Mduduzi Mbuya is the coauthor of a new study in the Lancet Global Health, which measured the impact of large-scale food fortification programs in 185 countries, and his team found that based on the best available data, these programs prevent 7 billion nutrient gaps worldwide. So this is basically evidence that these programs do have a massive impact.
BARBER: And they estimate that even more nutrient gaps could be prevented if food fortification programs had higher compliance. This involves manufacturers consistently fortifying staple foods at the levels required by national standards.
KWONG: As an example, a nutrient gap in folic acid has been linked to neural tube defects in infants, and that's why California now requires manufacturers to add folic acid to corn masa flour, which is used to make tortillas. Yeah. Alabama will follow suit with a similar law in June.
SUMMERS: All right. So I think my takeaway from all of this is that I've really got to start eating my vegetables and tortillas.
SUMMERS: We've been talking with Emily Kwong and Regina Barber, from NPR's science podcast Short Wave, which you can follow on the NPR app or wherever you get your podcasts. Thanks to both of you.
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