Dr. Adit Ginde, a University of Colorado-Denver surgery professor, says if you want to beat the flu or a cold in the winter, don’t necessarily think of orange juice–or anything else infused with vitamin C. Think instead of the vitamin D that comes from the sun’s rays. It appears to do the body’s immune system good, writes The Denver Post, which notes that Ginde’s report, a collaboration with Harvard Medical School, is the largest analysis on the subject thus far.

The study of 19,000 people finds that those with lower levels of vitamin D in their blood are about 40 percent more likely to have a respiratory infection. But don’t count good ol’ orange juice out just yet–even if one company is facing a marketing disaster of New Coke proportions.

Tropicana Pure Premium orange juice redesigned its packages early this year only to face an uproar. The new design appeared “generic” and bland, writes The New York Times, so Tropicana will bring back its old image: an orange from which a straw protrudes.