Adult men and women should consume 15 micrograms of vitamin D daily, but a specific amount of D-3 is not given, according to a report on SFGate.com, the online news publication of the San Francisco Chronicle. This can be fulfilled by certain foods, exposure to sunlight or a supplement.
Vitamin D-3 is important to the body because it allows growth, strengthens and maintains bones, and helps the immune and nervous systems function. It is critical to bones because it allows them to metabolize calcium. It can be found naturally in salmon, tuna, cheese and eggs. If a person doesn't regularly ingest these foods, taking a vitamin D supplement is necessary to meet the daily amount of 15 micrograms or 600 international units adults need, according to SFGate. People can intake vitamin D-3 naturally by being outside in the sun. The best way to get this vitamin is through food. Consuming enough vitamin D-3 each day keeps bones strong to prevent osteoporosis.