Vitamin D-3, also known as cholecalciferol, is the type of vitamin D produced when your skin is exposed to sunlight. Vitamin D-3 is a fat-soluble vitamin, which means it has the ability to dissolve in fats and oils. It's fat-soluble properties affect how your body processes and stores vitamin D, its potential for toxicity, as well as its absorption through your digestive tract.
There are two major classes of vitamins, differing mainly by your body's ability to store them. Fat-soluble vitamins, in addition to vitamin D include vitamins A, E and K. Your liver and fatty tissues can store fat-soluble vitamins for use in the future. Because vitamin D from your food is fat-soluble, it dissolves in fat droplets, and you need to consume vitamin D-containing foods with a small amount of fat to promote proper absorption.
One of vitamin D-3's most important roles in your body is to maintain the appropriate amount of calcium and phosphorus. It helps increase the amount of calcium you absorb from your small intestine. In children, vitamin D is important for developing bones and teeth. Milk and dairy products are good sources of vitamin D, but you can also find it in fatty fish like salmon, sardines and cod liver oil. Of course, the easiest way to obtain vitamin D-3 is simply through sunlight.
Aside from infants, most people need 15 micrograms of vitamin D daily until about age 70, when your need goes up to 20 micrograms. That's approximately 600 and 800 international units, respectively. The Institute of Medicine states that pregnant and nursing women do not need additional vitamin D. Although severe vitamin D deficiencies are rare, many people suffer from mild deficiency, notes the Linus Pauling Institute. Maintaining healthy vitamin D levels may provide protection from common cancers, autoimmune diseases, hypertension and several autoimmune diseases.
You must carefully balance fat-soluble vitamins in your diet. Because your body can store them, excess intake is possible and can be a potentially life-threatening problem. Colorado State University Extension notes that eating a normal, well-balanced diet shouldn't lead to toxicity of vitamin D-3 in otherwise healthy people. However, taking large doses of vitamin supplements, in addition to eating vitamin D-rich foods, as well as sun exposure, can pose risks.