Low levels of Vitamin D have been found to have a strong correlation between poor heart health and earlier death, even when several other factors are controlled for. In the US, poor diet has led to Vitamin D deficiency actually being quite common—especially in older children.
When you can’t get outside daily, it’s important to take a multivitamin. Your body needs 15-20 minutes (depending on altitude and how far north you are) of full skin sunlight daily, and unless you walk around during fall in a bikini, you’re probably not getting that.
Food can also be a source of Vitamin D, but your diet would have to be pretty healthy to get all the Vitamin D you need daily from it. Low levels of Vitamin D are all it takes to increase your risk for adverse health effects. Besides heart health, it’s also been correlated to obesity and other overall health problems. In the winter, it might contribute to SAD (Seasonal Affective Disorder). If you get depressed during the winter, your Vitamin D levels might be low! Sit in a window, eat your veggies, and take your vitamins!
Have you noticed the importance of Vitamin D in your own health? i.e., starting a multivitamin or getting some sun improved how you felt during winter?