Vitamin D3, also known as cholecalciferol, occurs naturally in the body and is particularly important in maintaining bone mineral density and blood calcium levels. Vitamin D, which comprises both vitamin D2 and D3, is not a true vitamin, as it is made in our own bodies with the help of the sun's ultraviolet rays. Few foods naturally contain vitamin D3, and humans receive most of their daily intake through sunlight. However, dietary sources of vitamin D3 are particularly important if you don't spend much time in direct sunlight due to health, lifestyle or geographical reasons.
Fatty Fish
Fish such as salmon, tuna and mackerel are very good sources of vitamin D. Other sources include sardines and shrimp. If you are buying salmon specifically for its vitamin D content, consider purchasing wild salmon. According to research by the Vitamin D, Skin, and Bone Research Laboratory of the Boston University Medical Center, wild salmon contains a significantly larger amount of vitamin D3 than farmed salmon. The study found that farmed salmon, on average, had only 25 percent of the vitamin D content found in wild salmon.
Cod Liver Oil
Cod liver oil can be used to provide some vitamin D3. The recommended intake is 1 or 2 tsp. a day for an adult. Ensure it is a high-quality, natural cod liver oil, with its full natural complements of vitamins A and D. Some processed cod liver oils may have the natural vitamins removed and replaced with synthetic vitamin A and vitamin D2. Small amounts of vitamin D3 are also found in beef liver.
Eggs
Vitamin D3 is stored in the yolk of eggs. In addition to vitamin D3, eggs contain significant levels of the more active hydroxylated metabolite, 25-hydroxy-vitamin D3, according to the Bio-Medicine website.
Fortified Foods
Some foods are fortified with added vitamin D. These foods include some breakfast cereals, some processed milks, infant foods and margarine. Milk is the most common dietary source of vitamin D. According to a 2000 report by the Department of Biochemistry and Biomedical Sciences at the University of California, natural cow's milk contains approximately 35 to 80 international units, or IU, of vitamin D3 per quart. Fortified milk, in comparison, offers significantly higher levels--about 400 IU of chemically synthesized vitamin D3 is added per quart in the United States.
References
- Office of Dietary Supplements: Dietary Supplement Fact Sheet: Vitamin D
- PubMed: An Evaluation of the Vitamin D3 Content in Fish: Is the Vitamin D Content Adequate to Satisfy the Dietary Requirement for Vitamin D? (Boston University Medical Center)
- Vitamin D3 -- Cholecalciferol: Vitamin D Sources
- Bio-Medicine: Raise Eggs' Vitamin D3 Content Sevenfold by Adding More Vitamin D to Chicken Feed
- University of California, Riverside: Vitamin D and Milk
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