In Real Life, SPF 100 Sunscreens May Work Better Than SPF 50

In Real Life, SPF 100 Sunscreens May Work Better Than SPF 50

Sunscreens with a rating of SPF 100 may be more effective than ones rated SPF 50, according to a randomized trial, even though the Food and Drug Administration says that any SPF above 50 offers no additional protection.

The study, in the Journal of the American Academy of Dermatology, included 199 men and women given two tubes of sunscreen, one marked “right” and one “left.” They applied the cream to the indicated side of the face and neck, and then went about their normal activities on a sunny day at a ski resort. One of the tubes contained SPF 50 cream, the other SPF 100.

The next day, a dermatologist rated the severity of burn on a 5-point scale from none to most severe. On average, the score was more than twice as high for the SPF 50 side of the face as for the SPF 100.


The reason may be that in practice, people almost never put on enough sunscreen.

“If you look at the laboratory results, you don’t see much of difference between 100 and 50,” said the senior author, Dr. Darrell S. Rigel, a professor of dermatology at New York University. “But in the real world, the higher SPFs are much more forgiving, and since people are under-applying sunscreen, they’re much more likely to protect.”


This article was originally published in The New York Times.  Read the original article.

Exercise may help make heart younger

Exercise may help make heart younger

In a new study performed in mice, researchers from the Harvard Department of Stem Cell and Regenerative Biology (HSCRB)Massachusetts General Hospital (MGH)Harvard Medical School (HMS), and the Harvard Stem Cell Institute (HSCI) uncovered one explanation for why exercise might be beneficial: It stimulates the heart to make new muscle cells, both under normal conditions and after a heart attack.

Just published in the journal Nature Communications, the findings have implications for public health, physical education, and the rehabilitation of cardiac patients.

The human heart has a relatively low capacity to regenerate itself. Young adults can renew around 1 percent of their heart muscle cells every year, and that rate decreases with age. Losing those cells is linked to heart failure, so interventions that increase cell formation have the potential to help prevent it.

The two first authors on the study were Ana Vujic of HSCRB and Carolin Lerchenmüller of MGH and HMS. Vujic said, “We wanted to know whether there is a natural way to enhance the regenerative capacity of heart muscle cells. So we decided to test the one intervention we already know to be safe and inexpensive: exercise.”

To test its effects, the researchers gave one group of healthy mice voluntary access to a treadmill. When left to their own devices, the mice ran about 5 kilometers each day. The other healthy group had no such gym privileges, and remained sedentary.

To measure heart regeneration in the mouse groups, the researchers administered a labeled chemical that was incorporated into newly made DNA as cells prepared to divide. By following the labeled DNA in the heart muscle, the researchers could see where cells were being produced. They found that the exercising mice made more than 4.5 times the number of new heart muscle cells as did the mice without treadmill access.

The results were significant, but were they relevant? To find out, the researchers brought the experiment a little closer to home.

“We also wanted to test this in the disease setting of a heart attack, because our main interest is healing,” said Vujic.

After experiencing heart attacks, mice with treadmill access still ran 5 kilometers a day, voluntarily. Compared with their sedentary counterparts, the exercising mice showed an increase in the area of heart tissue where new muscle cells are made.

The conclusion was that in mice, exercise means regenerating heart tissue — a lot of it.

The two senior authors behind the study were Richard Lee, Harvard professor of stem cell and regenerative biology and a principal faculty member of HSCI, and Anthony Rosenzweig, Paul Dudley White Professor of Medicine at HMS, chief of the cardiology division at MGH, and a principal faculty member of HSCI.

“Maintaining a healthy heart requires balancing the loss of heart muscle cells due to injury or aging with the regeneration or birth of new heart muscle cells. Our study suggests exercise can help tip the balance in favor of regeneration,” said Rosenzweig.

“Our study shows that you might be able to make your heart younger by exercising more every day,” said Lee.

It’s all very well to say that exercise is good for the heart, but how does that actually work? The researchers plan to pinpoint which biological mechanisms link exercise with increased regenerative activity in the heart.

“If we can turn on these pathways at just the right time, in the right people, then we can improve recovery after a heart attack,” said Lee.


This article was originally published in Harvard’s Wyss Institute. Read the original article.