Dr. Oz: 4 Warning Signs You Should Never Ignore
For some diseases, the red flags are changing. Here's what to watch out for now.
While doctors have thought for years that a D deficiency can increase the risk of respiratory infections, a 2013 Finnish study found that people with the lowest vitamin D levels were 2.6 times more likely to develop pneumonia than those with the highest, suggesting that the vitamin is essential to a strong immune system. All it takes to reach your daily quota of D is ten to 15 minutes in the sun three times per week. Note that simply opening the curtains isn't enough—the UVB rays your body needs can't penetrate windows.