Here is an extensive information on Vitamin D. Please visit the link to see the tables information much better. As you can see Cod liver oil blows other Vitamin D sources by a mile. Cod liver oil has 1360 IU of Vitmain D versus the next Vitmain D source of 360 IU.
http://ods.od.nih.gov/factsheets/vitamind.aspWhat is vitamin D?
Vitamin D is a fat soluble vitamin that is found in food and can also be made in your body after exposure to ultraviolet (UV) rays from the sun. Sunshine is a significant source of vitamin D because UV rays from sunlight trigger vitamin D synthesis in the skin [1-2].
Vitamin D exists in several forms, each with a different level of activity. Calciferol is the most active form of vitamin D. Other forms are relatively inactive in the body. The liver and kidney help convert vitamin D to its active hormone form [3]. Once vitamin D is produced in the skin or consumed in food, it requires chemical conversion in the liver and kidney to form 1,25 dihydroxyvitamin D, the physiologically active form of vitamin D. Active vitamin D functions as a hormone because it sends a message to the intestines to increase the absorption of calcium and phosphorus [3].
The major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus [3-4]. By promoting calcium absorption, vitamin D helps to form and maintain strong bones. Vitamin D also works in concert with a number of other vitamins, minerals, and hormones to promote bone mineralization. Without vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults, two forms of skeletal diseases that weaken bones [5-6].
Research also suggests that vitamin D may help maintain a healthy immune system and help regulate cell growth and differentiation, the process that determines what a cell is to become [3,7,8].
What are the sources of vitamin D?
Food Sources
Fortified foods are common sources of vitamin D [4]. In the 1930s, rickets was a major public health problem in the United States (U.S.). A milk fortification program was implemented to combat rickets, and it nearly eliminated this disorder in the U.S. [4,9]. About 98% to 99% of the milk supply in the U.S. is fortified with 10 micrograms (ìg) (equal to 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 for adults between the ages of 19 and 50, one-fourth of the recommended daily intake for adults between the ages of 51 and 70, and approximately 15% of the recommended daily intake for adults age 71 and over.
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 and contain only small amounts. Some ready-to-eat breakfast cereals may be fortified with vitamin D, often at a level of 10% to 15% of the Daily Value*. There are only a few commonly consumed foods that are good sources of vitamin D [4]. Suggested dietary sources of vitamin D are listed in Table 1.
Table 1: Selected food sources of vitamin D [10-12]
Food International Units(IU) per serving Percent DV*
Cod liver oil, 1 Tablespoon 1,360 340
Salmon, cooked, 3½ ounces 360 90
Mackerel, cooked, 3½ ounces 345 90
Tuna fish, canned in oil, 3 ounces 200 50
Sardines, canned in oil, drained, 1¾ ounces 250 70
Milk, nonfat, reduced fat, and whole, vitamin D fortified, 1 cup 98 25
Margarine, fortified, 1 Tablespoon 60 15
Pudding, prepared from mix and made with vitamin D fortified milk, ½ cup 50 10
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) 40 10
Egg, 1 whole (vitamin D is found in egg yolk) 20 6
Liver, beef, cooked, 3½ ounces 15 4
Cheese, Swiss, 1 ounce 12 4
*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) 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 (10 μg) for adults. Most food labels do not list vitamin D content unless a food has been fortified with this nutrient. The percent DV (%DV) listed on the table above tells you the percent of the DV provided in one serving. A food providing 5% of the DV or less is a low source while a food that provides 10-19% of the DV is a good source and a food that provides 20% or more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet. For foods not listed in this table, please refer to the U.S. Department of Agriculture’s Nutrient Database Web site: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl.
Sun exposure
Sun exposure is perhaps the most important source of vitamin D because exposure to sunlight provides most humans with their vitamin D requirement [13]. UV rays from the sun trigger vitamin D synthesis in skin [13-14]. 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. Complete cloud cover halves the energy of UV rays, and shade reduces it by 60%. Industrial pollution, which increases shade, also decreases sun exposure and may contribute to the development of rickets in individuals with 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, but it is still important to routinely use sunscreen to help prevent skin cancer and other negative consequences of excessive sun exposure. An initial exposure to sunlight (10 -15 minutes) allows 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]. It is very important for individuals with limited sun exposure to include good sources of vitamin D in their diet.
What is the recommended intake for vitamin D?
Recommendations for vitamin D are provided in the Dietary Reference Intakes (DRIs) developed by the Institute of Medicine (IOM) of the National Academy of Sciences [4]. Dietary Reference Intakes is the general term for a set of reference values used for planning and assessing nutrient intake for healthy people. Three important types of reference values included in the DRIs are Recommended Dietary Allowances (RDA), Adequate Intakes (AI), and Tolerable Upper Intake Levels (UL). The RDA recommends the average daily intake that is sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals in each age and gender group [4]. An AI is set when there is insufficient scientific data available to establish a RDA. AIs meet or exceed the amount needed to maintain a nutritional state of adequacy in nearly all members of a specific age and gender group. The UL, on the other hand, is the maximum daily intake unlikely to result in adverse health effects [4].
The IOM 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.
AIs for vitamin D may be listed on food and dietary supplement labels as either micrograms (μg) or International Units (IU). The biological activity of 1 μg vitamin D is equal to 40 IUs [4]. AIs for vitamin D for infants, children, and adults, are listed in table 2 in micrograms and IUs [4].
Table 2: Adequate Intake for vitamin D for infants, children, and adults [4]
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)
According to the IOM's report on the Dietary Reference Intakes for vitamin D, food consumption data suggest that median intakes of vitamin D for both younger and older women are below current recommendations [4]. Median intake refers to a statistical mid-point. Half of the population surveyed consumed more than the median intake while half consumed less. In this case, data suggest that more than 50% of younger and older women are not consuming recommended amounts of vitamin D.
In 2002, the vitamin D intakes of 1,546 non-Hispanic African American women and 1,426 non-Hispanic white women of reproductive age (15 to 49 years) were estimated by analyzing intake of milk and fortified cereals, two common dietary sources of vitamin D [16]. Blood levels of vitamin D were also examined in these groups. Data examined were from the National Health and Nutrition Examination Survey (NHANES) III survey, which interviewed people from randomly selected households all across the U.S. The prevalence of hypovitaminosis D, a term used to describe low blood levels of vitamin D, was 42.4% among African American women and 4.2% among white women. In both groups, blood levels of vitamin D were higher when milk or fortified cereals were consumed more than 3 times per week. Among African American women, the risk of hypovitaminosis D decreased as milk and fortified cereal intake increased. These numbers suggest that large numbers of African American women may not consume recommended amounts of vitamin D. More frequent intake of vitamin D fortified milk and fortified cereals may help prevent hypovitaminosis D in this group.
When can vitamin D deficiency occur?
# Nutrient deficiencies are usually the result of dietary inadequacy, impaired absorption and utilization, increased requirement, or increased excretion (loss). A deficiency of vitamin D can occur [9]: when usual intake is below recommended levels
# when there is limited exposure to sunlight
# when the kidney cannot convert vitamin D to its active hormone form
# when someone cannot adequately absorb vitamin D from the digestive tract
Vitamin D deficient diets are associated with milk allergy, lactose intolerance, and strict vegetarianism. Infants fed only breast milk also receive insufficient amounts of vitamin D unless they also receive appropriate levels of vitamin D supplementation [17].
The classic vitamin D deficiency diseases are rickets and osteomalacia. In children, vitamin D deficiency causes rickets. Rickets is a bone disease characterized by a failure to properly mineralize bone tissue. Rickets results in soft bones and skeletal deformities [15]. Rickets was first described in the mid-17th century by British researchers [15,18]. In the late 19th and early 20th century, German physicians noted that consuming 1 to 3 teaspoons (3 teaspoons is equal to 1 tablespoon) of cod liver oil per day could reverse rickets [18]. The most common causes of rickets are vitamin D deficiency from a vitamin D deficient diet, lack of sunlight, or both. The recommendation to fortify milk with vitamin D made rickets a rare disease in the U.S. for many years. However, rickets has recently reemerged, in particular among African American infants and children [15,18]. In 2003, a report from Memphis, Tennessee, described 21 cases of rickets among infants, 20 of whom were African-American [18].
Prolonged exclusive breastfeeding without vitamin D supplementation is one of the most significant causes of the reemergence of rickets. Additional causes include extensive use of sunscreens and increased use of day-care, resulting in decreased outdoor activity and sun exposure among children [15,18].
Rickets is more prevalent among immigrants from Asia, Africa, and Middle Eastern countries for a variety of reasons [15]. Among immigrants, vitamin D deficiency has been associated with iron deficiency, leading researchers to question whether or not iron deficiency may impair vitamin D metabolism [15]. Immigrants from these regions are also more likely to follow dress codes that limit sun exposure. In addition, darker pigmented skin converts UV rays to vitamin D less efficiently than lighter skin [15].
In adults, vitamin D deficiency can lead to osteomalacia, which results in muscular weakness in addition to weak bones [5-6,9]. Symptoms of bone pain and muscle weakness may indicate vitamin D deficiency, but symptoms may be subtle and go undetected in the initial stages. A deficiency is accurately diagnosed by measuring the concentration of a specific form of vitamin D in blood [9,14].
Who may need extra vitamin D to prevent a deficiency?
It can be difficult to obtain enough vitamin D from natural food sources. For many people, consuming vitamin D fortified foods and adequate sunlight exposure are essential for maintaining a healthy vitamin D status. In some groups, dietary supplements may be needed to meet the daily need for vitamin D.
Infants who are exclusively breastfed
In infants, vitamin D requirements cannot be met by human (breast) milk alone [4,19], which usually provides approximately 25 IU vitamin D per liter [20]. Sunlight is a potential source of vitamin D for infants, but the American Academy of Pediatrics (AAP) advises that infants be kept out of direct sunlight and wear protective clothing and sunscreen when exposed to sunlight [21]. The American Academy of Pediatrics (AAP) recommends a daily supplement of 200 IU vitamin D for breastfed infants beginning within the first 2 months of life unless they are weaned to receive at least 500 ml (about 2 cups) per day of vitamin D-fortified formula [20]. Children and adolescents who are not routinely exposed to sunlight and do not consume at least 2, 8-fluid ounce servings of vitamin D-fortified milk per day are also at higher risk of vitamin D deficiency and may need a dietary supplement containing 200 IU vitamin D [20].
Formula fed infants usually consume recommended amounts of vitamin D because the 1980 Infant Formula Act requires that infant formulas be fortified with vitamin D. The minimal level of fortification required is 40 IU vitamin D per 100 calories of formula. The maximum level of vitamin D fortification allowed is 100 IU per 100 calories of formula [22]. This range of fortification produces a standard 20 calorie per ounce formula providing between 265 and 660 IU vitamin D per liter.
Older adults
Americans age 50 and older are believed to be at increased risk of developing vitamin D deficiency [14]. As people age, skin cannot synthesize vitamin D as efficiently and the kidney is less able to convert vitamin D to its active hormone form [4,23-26]. It is estimated that as many as 30% to 40% of older adults with hip fractures are vitamin D insufficient [13]. Therefore, older adults may benefit from supplemental vitamin D.
Persons with limited sun exposure
Homebound individuals, people living in northern latitudes such as in New England and Alaska, women who wear robes and head coverings for religious reasons, and individuals working in occupations that prevent sun exposure are unlikely to obtain much vitamin D from sunlight. It is important for people with limited sun exposure to consume recommended amounts of vitamin D in their diets or consider vitamin D supplementation [27-29].
Persons with greater skin melanin content
Melanin is the pigment that gives skin its color. Greater amounts of melanin result in darker skin. The high melanin content in darker skin reduces the skin's ability to produce vitamin D from sunlight. It is very important for African Americans and other populations with dark-pigmented skin to consume recommended amounts of vitamin D. Some studies suggest that older adults, especially women, in these groups are at even higher risk of vitamin D deficiency [16,30]. Individuals with darkly pigmented skin who are unable to get adequate sun exposure and/or consume recommended amounts of vitamin D may benefit from a vitamin D supplement.
Persons with fat malabsorption
As a fat soluble vitamin, vitamin D requires some dietary fat for absorption. Individuals who have a reduced ability to absorb dietary fat may require vitamin D supplements [31]. Symptoms of fat malabsorption include diarrhea and oily stools [31]. Fat malabsorption is associated with a variety of medical conditions [9]:
Pancreatic enzyme deficiencyis characterized by insufficient secretion of pancreatic enzymes. Pancreatic enzymes are essential for fat absorption, and a deficiency of these enzymes can result in fat malabsorption.
Crohn's Disease is an inflammatory bowel disease that affects the small intestines. People with Crohn's disease often experience diarrhea and fat malabsorption.
Cystic Fibrosis (CF) is a hereditary disorder that causes the body to secrete a thick, sticky mucus. This mucus clogs the pancreas and lungs. People with CF often experience fat malabsorption.
Sprue, often referred to as Celiac Disease (CD), is a genetic disorder. People with CD are intolerant to a protein called gluten. In CD, gluten can trigger damage to the small intestines, where most nutrient absorption occurs. People with CD often experience fat malabsorption. They need to follow a gluten free diet to avoid malabsorption and other symptoms of CD.
Liver disease includes a wide variety of disorders that impair liver function. Some people with liver disease experience fat malabsorption.
Surgical removal of part or all of the stomach or intestines can impair digestion and absorption of many nutrients. Fat malabsorption can occur after this type of surgery.