Food Sources of Vitamin D

In the 1930s, a vitamin D deficiency disease called rickets was a major public health problem in the United States so a milk fortification program was implemented nearly eliminating this disorder.4,9 Currently, about 98% of the milk supply in the US is fortified with 400 International Units (IU) of vitamin D per quart.

Although milk is fortified with vitamin D, dairy products made from milk, such as cheese and ice creams, are generally not fortified with vitamin D.

There are only a few foods that are good sources of vitamin D,4 so vitamin D supplements are often recommended unless you are exposed to sunlight on your skin regularly. Suggested dietary sources of vitamin D are listed below.

Table 1: Selected food sources of vitamin D10-12

International Units(IU)
per serving
Percent DV
Pure Cod liver oil, 1 Tablespoon (Note: most refined cod liver oils today have the vitamin D removed! Check your label to be certain.)
Salmon, cooked, 3½ ounces
Mackerel, cooked, 3½ ounces
Tuna fish, canned in oil, 3 ounces
Sardines, canned in oil, drained, 1¾ ounces
Milk, nonfat, reduced fat, and whole, vitamin D fortified, 1 cup
Margarine, fortified, 1 Tablespoon
Pudding, prepared from mix and made with vitamin D fortified milk, ½ cup
Ready-to-eat cereals fortified with 10% of the DV for vitamin D, ¾ cup to 1 cup servings (servings vary according to the brand)
Egg, 1 whole (vitamin D is found in egg yolk)
Liver, beef, cooked, 3½ ounces
Cheese, Swiss, 1 ounce
*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for vitamin D is 400 IU for adults.

Sun Exposure as a Vitamin D Source

Exposing yourself to sunlight is the most important source of vitamin D because sunlight is far more likely to provide you with your vitamin D requirement than food is.13 UV rays from the sun trigger vitamin D production in your skin.13-14 Lights from your home are not strong enough to produce vitamin D. Season, geographic latitude, time of day, cloud cover, smog, and sunscreen affect UV ray exposure and vitamin D synthesis.14 For example, sunlight exposure from November through February in Boston is insufficient to produce significant vitamin D synthesis in the skin.

Obviously any point of north of Boston is worse. Complete cloud cover halves the energy of UV rays, and shade reduces it by 60%. Industrial pollution also filters sun exposure and may contribute to the development of rickets if you have insufficient dietary intake of vitamin D.15

Sunscreens with a sun protection factor (SPF) of 8 or greater will block UV rays that produce vitamin D. An initial exposure to sunlight of 10 to15 minutes allows you adequate time for Vitamin D synthesis and should be followed by application of a sunscreen with an SPF of at least 15 to protect the skin. Ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen is usually sufficient to provide adequate vitamin D.14 If you have limited sun exposure it is very important that you include good sources of vitamin D in your diet or supplement with AlgaeCal® Plus.

What is the Recommended Intake for Vitamin D?

The RDA, developed by the Institute of Medicine of the National Academy of Sciences,4 recommends the average daily intake that is sufficient to meet the nutrient requirements of healthy individuals in each age and gender group. An Adequate Intake (AI) is set when there is insufficient scientific data available to establish a RDA.

The Institute of Medicine determined there was insufficient scientific information to establish a RDA for vitamin D. Instead, the recommended intake is listed as an Adequate Intake (AI), which represents the daily vitamin D intake that should maintain bone health and normal calcium metabolism in healthy people. Vitamin D AI for infants, children, and adults, are listed below in International Units.4

Daily Adequate Intake of Vitamin D

Age Children Men Women Pregnancy Lactation
Birth to 13 years 200 IU
14 to 18 years 200 IU 200 IU 200 IU 200 IU 200 IU
19 to 50 years 200 IU 200 IU 200 IU 200 IU 200 IU
51 to 70 years 400 IU 400 IU
71 + years 600 IU 600 IU

According to the Institute of Medicine, food consumption data suggests intakes of vitamin D for both younger and older women are below current recommendations.4 The data suggests more than 50% of younger and older women are not consuming recommended amounts of vitamin D. Their data also shows African American women are particularly prone to consuming low amounts of vitamin D in their diet.

What is the Best Form of Vitamin D Supplement?

Houghton, in a 2006 article appearing in the American Journal of Clinical Nutrition18 points out that vitamin D2, the synthetic variety used for fortification of milk and foods, is inferior to the natural form, vitamin D3 for several reasons. He suggests D2 “should not be regarded as a nutrient suitable for supplementation or fortification.”

Authors Goldberg, and Cantorna, show it is very important to take adequate calcium and magnesium along with vitamin D3 supplementation as the three balance each other.

More Vitamin D May Be Better!

Recent science is showing that levels above the Adequate Intake may provide better health. For example, professor Robert Heaney has reported in April 2006 in the Journal of Nutrition his study showing an additional 2600 IU/day of oral vitamin D3 should be given to older women.15

Vieth reported in the American Journal of Clinical Nutrition a recommendation of 4000 IU per day for adults.16 He also showed that levels of 10,000 IU per day were normal from body exposure to the sun and the only published vitamin D toxicity was at levels exceeding 40,000 IU/day.

The National Institutes of Health indicates Vitamin D may have benefit for some forms of Cancer, Osteoporosis, Alzheimers, Chron’s Disease and other maladies.17

It seems more studies are warranted on proper vitamin D levels. Given that vitamin D3 is safe at very high levels and may provide extraordinary benefits with no known risk, we recommend individuals get reasonable sun exposure, eat foods rich in vitamin D, and supplement with AlgaeCal Plus.

Read more about the latest studies involving calcium and vitamin D reducing the risk of cancer.