It’s true – you’re much more likely to die of a heart attack during the winter, than in the summer. But a surprising new study found that it’s not the cold weather, or shoveling snow that puts you at risk. In fact, cold weather might not be a factor at all!

Dr. Bryan Schwartz is a cardiovascular researcher at Good Samaritan Hospital in Los Angeles. His study found that people are 26 to 36 percent more likely to die during the winter from a stroke, heart attack, heart failure, or other circulatory disease.  But he was surprised that the numbers held steady across the board, whether people lived in snowy areas, mild conditions or the hottest desert.

So, what’s the real reason winter is so deadly? Researchers point to two factors: First, winter days are shorter, so people are more likely to feel down and discouraged.  And chemical changes connected to depression can increase stress on your cardiovascular system. People who are depressed are also less likely to exercise, and take their prescription meds.  And are more likely to eat high-fat, high-calorie comfort foods.

To make up for the darker days of winter, experts suggest getting more vitamin D in your diet. Say, by having an egg for breakfast every day, or adding more fish to your diet – like salmon, tuna, or mackerel – which are loaded with vitamin D. That’ll lower your heart attack risk by 45 percent!

The other risk factor for winter heart attacks: The flu! Flu season peaks during the winter.  And it can worsen chronic medical conditions, like asthma, diabetes, and congestive heart failure. That’s because the flu virus triggers inflammation, which disrupts healthy blood-flow. Experts say that at least 90,000 heart-attack deaths could be prevented each year, if we all got a flu shot!