What is Vitamin D?
Unique in the fact that the body can synthesize all it needs with help from the sun, Vitamin
D is a one-of-a-kind nutrient. By simply exposing oneself to enough sun each day there is
no need to consume Vitamin D at all from foods.
The most important function Vitamin D plays within the human body is its role in helping to
maintain normal blood levels of calcium and phosphorus. By assisting the body with calcium
absorption, Vitamin D helps to create and maintain strong bones. Without adequate levels
of Vitamin D, the bones can become thin, brittle and misshapen.
Essentially, Vitamin D functions as a hormone, that is, a chemical substance which is formed
in one organ or part of the body and is carried in the blood to another organ where it
alters the function of another organ. Vitamin D is used by various body parts such as the
brain, heart, intestines, kidneys and even the reproductive organs. Research also suggests
that Vitamin D may play a role in maintaining a healthy immune system.
Recommended Daily Intake
Because there is insufficient scientific information available to establish a Recommended
Daily Allowance for Vitamin D, the table below lists the Adequate Intake (AI) level,
which represents the amount of Vitamin D that is needed to maintain bone health and normal
calcium metabolism.
When looking at food and dietary supplement labels, you may notice that the AI’s for
Vitamin D are listed as either micrograms (μg) or International Units (IU). For reference,
1 μg = 40 IU.
| Age |
Children (μg/day) |
Men (μg/day) |
Women (μg/day) |
Pregnancy (μg/day) |
Lactation (μg/day) |
| Birth to 13 years |
5 (=200 IU) |
|
|
|
|
| 14 to 18 years |
|
5 (=200 IU) |
5 (=200 IU) |
5 (=200 IU) |
5 (=200 IU) |
| 19 to 50 years |
|
5 (=200 IU) |
5 (=200 IU) |
5 (=200 IU) |
5 (=200 IU) |
| 51 to 70 years |
|
10 (=400 IU) |
10 (=400 IU) |
|
|
| 71+ years |
|
15 (=600 IU) |
15 (=600 IU) |
|
|
Sources of Vitamin D
Fortified foods are common sources of vitamin D. In the 1930’s, rickets was a major public
health problem in the United States. A milk fortification program was implemented to combat
rickets, and it nearly eliminated this disorder in the U.S. About 98% to 99% of the milk
supply in the U.S. is fortified with 10 micrograms (400 International Units or IU) of
vitamin D per quart. One cup of vitamin D fortified milk supplies one-half of the
recommended daily intake of adults between the ages of 19 and 50.
The following chart displays the Vitamin D content of various foods.
The following table lists foods that provide large quantities of Vitamin D, ranked by
International Units per Serving.
| Food, Standard Amount |
Vitamin D (IU) |
% Daily Value |
Calories |
| Cod Liver Oil, 1 Tbsp |
1360 |
340 |
123 |
| Salmon, cooked, 3½ oz |
360 |
90 |
201 |
| Mackerel, cooked, 3½ oz |
345 |
90 |
256 |
| Tuna fish, canned in oil, 3 oz |
200 |
50 |
198 |
| Sardines, canned in oil, 1¾ oz |
250 |
70 |
103 |
| Milk, nonfat, reduced fat, and whole, fortified, 1 cup |
98 |
25 |
86-138 |
| Margarine, fortified, 1 Tbsp |
60 |
15 |
102 |
| Pudding, made w/ vitamin D fortified milk, ½ cup |
50 |
10 |
197 |
| Egg, 1 whole (vitamin D found in egg yolk) |
20 |
6 |
72 |
| Liver, beef, cooked, 3½ oz |
15 |
4 |
220 |
| Cheese, Swiss, 1 oz |
12 |
4 |
106 |
Vitamin D Under/Over
The following table describes some of the symptoms that signify a lack of Vitamin D (Deficiency) and an
overabundance of Vitamin D (Toxicity).
| Deficiency Symptions |
|
Toxicity Symptons |
|
Blood/Circulatory System
|
| |
|
Raised blood calcium |
|
Bones/Teeth
|
| Abnormal growth, bowing of legs, soft bones, joint pain |
|
Calcification of tooth soft tissue; thinning of enamal on teeth |
|
Nervous System
|
| Muscle spasms |
|
Excessive thirst, irritability, headaches, nausea, weakness, loss of appetite |
|
Other
|
| |
|
Kidney stones, stones in arteries |
