With summertime here it’s a great chance to get your daily dose of vitamin D. Unlike most vitamins and minerals, which must be consumed through food, vitamin D can be manufactured in the body through the action of UV rays from the sun on one’s skin. This is wonderful, given that vitamin D is not super plentiful in food sources. So this summer spend about 15 minutes each day outside, basking in some natural sunlight!
What is Vitamin D?
Vitamin D is a fat-soluble vitamin that plays a part in maintaining strong bones. The main building block of bones is calcium, and since vitamin D aids in the absorption of calcium, it too is essential for bone health. If someone does not get adequate amounts of this vitamin their bones will become soft, brittle or porous, and may develop rickets or osteoporosis.
What Else Does Vitamin D Do?
Vitamin D is also essential for several other functions in the body. It is needed for carrying neural messages from the brain to other parts of the body, and is thus necessary for muscle movement. Vitamin D is needed for a strong immune system, as it helps fight off invading bacteria and viruses. There have also been several studies that indicate a correlation between low vitamin D levels and depression. We do not know which causes which, but we do know that vitamin D does play a part in brain function and positive mood.
What Foods Can I find Vitamin D In?
There are few foods that naturally contain vitamin D, so fortified foods provide most of it in the American diet. The following foods contain vitamin D:
- Fatty fish such as salmon, tuna, and mackerel are among the best sources
- Beef liver, cheese, and egg yolks provide small amounts
- Mushrooms provide some vitamin D (some mushrooms have the vitamin D content boosted by exposing these mushrooms to ultraviolet light)
- Almost all of the U.S. milk supply is fortified with 400 IU of vitamin D per quart. But foods made from milk, like cheese and ice cream, are usually not fortified
- Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and soy beverages; check the labels
How much Vitamin D Do I Need?
The amount of vitamin D an individual needs depends on the person’s age. The following table lists the Food & Nutrition Board’s recommendations in International Units (IU).
| Life Stage | Recommended Amount |
|---|---|
| Birth to 12 months | 400 IU |
| Children 1–13 years | 600 IU |
| Teens 14–18 years | 600 IU |
| Adults | 19–70 years 600 IU |
| Adults 71 years and older | 800 IU |
| Pregnant and breastfeeding women | 600 IU |
I Can Get Vitamin D From The Sun? How Does This Work?
Vitamin D is actually not technically a vitamin, since the body can create it; and it is not one chemical, but many. The natural type is produced in the skin from a form of cholesterol called 7-dehydrocholesterol. Sunlight is key in converting this precursor into vitamin D3 (D2 is created when plant sterols are exposed to UV rays). D3 gets carried to the liver and kidneys, where it is transformed into active vitamin D.
The body manufactures vitamin D when the skin is directly exposed to the sun, providing people with most of their needs for the day. However, cloudy days, shade and dark-colored skin cut down on the amount of vitamin D the skin makes. Also, it is wise to limit sun exposure to avoid developing skin cancer; 10-15 minutes a day should be enough.
