There are 3 main sources that we can gain vitamin D from, including sunlight, food and vitamin d tablets. We are recommended to gain between 400-800 international units (IU) of vitamin D every day, with this increasing after the age of 50 to 800-1000 IU to ensure that we are gaining all of the benefits of vitamin D and of course the benefits of calcium, without suffering from vitamin D deficiency.
Exposure to sunlight is the only way that we can gain vitamin D3 as our body synthesises it from the ultraviolet light (UVB) rays in sunlight. As your skin absorbs ultraviolet B rays from the sun, it is made into a substance called pre-vitamin D3. This then travels to the liver to become vitamin D3 or ?calcidiol' and is carried by special proteins to the kidneys to be turned into vitamin D's biologically active form ?calcitriol'.
Your body has the ability to store the vitamin D for later use. Of course, the amount of vitamin D3 that our bodies can make will depend on how much time we are fully exposed to the sunlight without any sun protection. This will also depend on other factors such as weather conditions (cloud cover) season, time of day and latitude as well as skin age and pigmentation. Gaining vitamin D from sunlight may also be difficult because of increasing concerns about sunlight and skin cancer, even though an SPF (sun protection factor) of 8 could reduce the production of vitamin D by 95%.
Vitamin D is only naturally available in a few foods, with the richest source being fatty fish like mackerel, salmon and tuna. Vitamin D may also be added to milk, some brands of dairy products, soymilk, cereals and orange juice. You will be able to look on food labels to see if anything has added vitamin D, but it is particularly difficult to gain vitamin D from food sources alone.
Considering that gaining vitamin D from sunlight and food alone is quite difficult, vitamin D supplements are becoming increasingly popular to ensure that we can gain all of vitamin D's benefits. Supplements will not only ensure that you are getting enough vitamin D, but this will also have a great effect on your body's absorption of calcium and enhance the benefits we can gain. Before you start taking a vitamin D supplement, make sure that it isn't already included in any other supplements or multivitamins that you are taking.
You can find 2 types of vitamin D tablets: vitamin D2 and vitamin D3, which are both great for bone health. You don't need to take vitamin D supplements at the same time as calcium supplements, as your body has the ability to store this vitamin.