Ask Tufts Experts

Should I buy sunscreen with the highest SPF available?

Not necessarily, but the American Academy of Dermatology says you shouldn’t go below an SPF of 15, either. An SPF, or Sun Protection Factor, of 15 means that it will take 15 times longer for skin to burn than it would if it were unprotected. A higher SPF does offer greater protection from UVB rays, but once you go above 15, the margin of protection doesn’t increase as much.

When selecting a sunscreen, look for one that provides broad-spectrum coverage, which means it protects against UVB and UVA rays, both harmful. And apply it 15 to 30 minutes before heading outdoors so it’s fully absorbed—and reapply every 2 hours or after swimming or perspiring heavily.

Which cheese is the best source of calcium?

An ounce of grated Parmesan cheese contains 391 milligrams, almost 40 percent of the 1,000-milligram Daily Value. But 1 ounce comes to 5.6 tablespoons (130 calories’ worth), more than anyone is likely to sprinkle over a pasta dish. Per tablespoon, Parmesan cheese contains 70 milligrams—still not bad, especially for a garnish.

Generally speaking, the harder the cheese, the more calcium it contains for its weight. An ounce of Swiss, cheddar, or Muenster contains more than 200 milligrams of calcium, while an ounce of feta or mozzarella has about 145.

Note that along with calcium, harder cheeses contain more saturated fat and calories than soft ones, which is why it’s good to use them judiciously—an ounce to an ounce and a half at a time.