Vitamin D, also called the sunshine vitamin, is critical for bone and immune health. It boosts bone health by increasing the amount of calcium you absorb from your gut and kidneys. Vitamin D also modulates the activity of the immune system, helping to finely tune it so it reacts against foreign invaders but doesn't promote inflammation. However, up to 75% of people are low or marginally low in vitamin D and there are lots of misunderstandings about this important vitamin. Here are five things you really need to know about vitamin D. 1. Food Isn't a Good Source of Vitamin D You might think you can meet your vitamin D needs through diet alone, but that's hard to do. Except for fatty fish, like salmon, cod liver oil, egg yolks, and foods fortified with vitamin D, most foods contain little or no vitamin D. Your body gets most of its vitamin D from sun exposure.When ultraviolet light rays hit your skin, your skin makes a vitamin D precursor from cholesterol. Your liver and kidneys activate this precursor to form vitamin D, also known as calcitriol. That's why sun exposure is so important for meeting your vitamin D requirements. 2. Vegans, Vegetarians or Dairy-Sensitive have challenges As mention in the previous item, the list of foods that contain vitamin D is short and almost entirely animal based. If you are Vegan, Vegetarian or Dairy sensitive and don’t eat fish, eggs, or dairy, it’s even harder to get vitamin D from your food. This means you’re getting even less vitamin D than the average person. And to make this even more challenging, most of vitamin D3 supplements in the market are also animal-based. X Gold Health Vitamin D3 is sustainably sourced from wild-harvested lichen with no animal byproducts of any kind. 3. Vitamin D Absorption is Low in the Absence of Dietary Fat If you take a vitamin D supplement, take it with a meal that contains fat. If you do, you'll absorb about 50% of the vitamin D from the supplement. If you don't, you'll only absorb about 25%. Vitamin D is a fat-soluble vitamin, and absorption is low in the absence of fat. So, for better results, take your supplement with a meal.Dr. Dawson-Hughes, director of the Bone Metabolism Laboratory at Tufts University, demonstrated the importance of fat for vitamin D absorption in a recent study in The Journal of the Academy of Nutrition and Dietetics. In the study, 50 healthy men and women took a large dose of vitamin D3 — 50,000 international units — with breakfast, and then provided blood samples throughout the day.Some of the subjects took the vitamin with a fat-free breakfast consisting of egg whites, fruit, toast and cranberry juice. The rest ate the same breakfast, but with either olive oil or corn oil mixed in so that it accounted for 30 percent of the calories. They tested two kinds of fat — monounsaturated (olive oil) and polyunsaturated (corn oil) — to...