Vitamin D is fat-soluble vitamin that has a significant role in our health. Without vitamin D, it would be impossible for our bodies to utilize calcium, have bone growth, maintain bone density, allow for normal functioning of the nervous system, prevent rickets in children and brittle bones. Vitamin D also supports our cell differentiation, directing cells in the right direction as our body produces them.

There are two ways we can reap the benefits of vitamin D. We can consume food or supplements containing vitamin D and our bodies can also make it after being exposed to the sun, specifically the ultraviolet rays from the sun. Even though using a sun screen blocks the ultraviolet rays, which are needed for the vitamin D, it's very important to use, if you plan on being out in the sun for extended period of time, in order to reduce the risk of skin cancer.

The liver and kidneys help convert vitamin D to an active hormone form. Calcium levels in the blood are balanced by Vitamin D by determining their absorption from food in the intestines and re-absorption of calcium in the kidneys. It promotes bone formation, but, if the level of the vitamin gets too high, it could have the reverse effect and bone could begin to deteriorate.

The are many reasons or conditions that may exist that can cause the body to experience a vitamin D deficiency. One reason is a lack of exposure to sunlight. If the kidneys aren't able to convert the vitamin to its active form, this will also result in a D deficiency. If the vitamin isn't being sufficiently absorbed through the gastrointestinal tract, or there's not enough vitamin D being consumed these conditions will also result in deficiencies.

Vitamin D isn't measured as many of our vitamins are, in terms of Recommended Dietary Allowance. It is measured in Adequate Intake, AI and it's the same for male and female alike. The vitamin, itself, is measured in International Units. The AI for ages 19-50 is 200 IUs, for 51-69 it's 400 IUs, and age 70 and up it's 600 IUs. Some of the most major food sources of vitamin D are cod liver oil, cooked salmon, cooked mackerel, canned sardines, milk, margarine, pudding, dry cereal, beef liver, and egg yolk.

Vitamin D deficiency increases with age and the risk of bone loss increases the risk of fractures. It's important to supplement your diet with a natural plant source vitamin D for optimal bone and teeth development. These plant source vitamins are also safe for pregnant and lactating women. The ingredients to look for in a vitamin that will provide all the required nutrients include alfalfa, red raspberry leaves, mullein leaves, eyebright, fenugreek seed, oat straw, thyme, rose hip seed, and sarsaparilla.