The Vitamin D Health Initiative™
"Over 3 out of every 4 Americans now have Vitamin D levels below what we believe is necessary for optimal health." - published in Archives of Internal Medicine, March 23
The Vitamin D Health Initiative™ was established to help get the word out about the current deficiency crisis, and the positive impact proper Vitamin D supplementation can have on your health. By helping get the word out, you can help make a huge impact on the health of our nation.
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Vitamin D Deficiency In America
Vitamin D deficiency is considered by many to be an epidemic seriously impacting the health of our nation.
A new study finds that over the past 20 years American's vitamin D levels are dramatically declining. The report was published in the March 23 issue of the Archives of Internal Medicine. Dr. Adit Ginde, an assistant professor of surgery at the University of Colorado Denver School of Medicine and the lead researcher on the study found a marked increase in vitamin D deficiency over the past two decades.
"Over three out of every four Americans now have vitamin D levels below what we believe is necessary for optimal health. African-Americans and Hispanics are at particularly high risk Ė nearly all have suboptimal levels."
Data was collected from 18,883 people between 1988 and 1994, and 13,369 people collected between 2001 and 2004 and examined their vitamin D levels. All the data came from the Third National Health and Nutrition Examination Survey.
According to findings of the Archives of Internal Medicine, and of the people studied 45 percent of people had 30 nanograms per milliliter or more of vitamin D, the blood level a growing number of doctors consider sufficient for overall health; a decade later, just 23 percent of 13,369 of those surveyed had at least that amount.
The greatest drops in vitamin D levels were seen among African Americans, where levels of vitamin D of less than 10 nanograms per milliliter rose from 9 percent to 29 percent, and levels of more than 30 nanograms per milliliter or higher dropped from 12 percent to 3 percent, the researchers found.
Increased Vitamin D Deficiency in Population on the Rise
"Increases in vitamin D deficiency in the population may have reduced the overall health of the population," Ginde said. "Since sunlight is the bodyís major source of vitamin D, increases in sunscreen, sun avoidance, and overall decreased outdoor activity, while successful in reducing skin cancers, has probably reduced vitamin D levels in the population."
Ten minutes of sunlight on exposed arms and legs two to three times per week would significantly improve vitamin D production, but must be weighed against the risk for skin cancer, Ginde noted. Vitamin D supplementation is another way to increase levels. However, current recommended doses of vitamin D supplements are outdated and inadequate, he added.
Right now, recommended levels of vitamin D supplements are 200 international units per day from birth to age 50, 400 international units (IU) per day from age 51 to 70, and 600 international units per day for adults aged 71 and older. These recommendations are primarily for improving bone health.
Vitamin D the Under Appreciated Public Health Issue
"Vitamin D is an important and under appreciated public health issue and may be responsible for some racial differences in health outcomes," Ginde said. "Most Americans could use more vitamin D. Higher doses of vitamin D supplementation than currently recommended, at least 1,000 to 2,000 IU daily, are likely needed to raise vitamin D levels for many people."
Dr. Michael F. Holick, director of the Vitamin D Laboratory at Boston University, and world renown vitamin D expert noted that the recommended levels of vitamin D are under review and likely to be increased.
Holick believes that by mid-2010 the Institute of Medicine will offer new recommendations. "It's pretty clear that you need a minimum of 1,400 and up to 2,000 IU a day, and if you are obese, you probably need at least one and a half to two times as much, because the fat sequesters the vitamin D," he said.
The fact is people are staying out of the sun and drinking less milk, which are the main reasons for the decreasing vitamin D levels in the population.
Holick believes one way to combat the problem is to increase vitamin D supplementation in foods. New recommendations that increase vitamin D levels will let the food industry increase vitamin D levels in foods and add vitamin D to more foods, he said.
"We are in desperate need to have a marked increase in the adequate intake recommendation, and hopefully, that will be 1,000 to 2,000 Ius per day and raise the safe upper limit to at least 10,000 IUs a day,"
Holick said. "The plan would be to increase the amount per serving and increase the number of foods fortified with vitamin D."
Groups at Risk of Vitamin D Inadequacy
Obtaining sufficient vitamin D from natural food sources alone can be difficult. For many people, consuming vitamin D-fortified foods and being exposed to sunlight are essential for maintaining a healthy vitamin D status. In many groups, dietary supplements might be required to meet the daily need for vitamin D.
Breast Fed Infants
Vitamin D requirements cannot be met by human milk alone, which provides only about 25 IU/L. A recent review of reports of nutritional rickets found that a majority of cases occurred among young, breastfed African Americans. The sun is a potential source of vitamin D, but AAP advises keeping infants out of direct sunlight and having them wear protective clothing and sunscreen.
As noted earlier, AAP recommends that exclusively and partially breastfed infants be supplemented with 400 IU of vitamin D per day.
Americans aged 50 and older are at increased risk of developing vitamin D insufficiency. 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. As many as half of older adults in the United States with hip fractures could have serum 25(OH)D levels <12 ng/mL (<30 nmol/L).
People With Limited Sun Exposure
Homebound individuals, people living in northern latitudes (such as New England and Alaska), women who wear long robes and head coverings for religious reasons, and people with occupations that prevent sun exposure are unlikely to obtain adequate vitamin D from sunlight.
People With Dark Skin
Greater amounts of the pigment melanin result in darker skin and reduce the skinís ability to produce vitamin D from exposure to sunlight. Some studies suggest that older adults, especially women, with darker skin are at high risk of developing vitamin D insufficiency. However, one group with dark skin, African Americans, generally has lower levels of 25(OH)D yet develops fewer osteoporotic fractures than Caucasians.
People With Fat Malabsorption
As a fat-soluble vitamin, vitamin D requires some dietary fat in the gut for absorption. Individuals who have a reduced ability to absorb dietary fat might require vitamin D supplements. Fat malabsorption is associated with a variety of medical conditions including pancreatic enzyme deficiency, Crohnís disease, cystic fibrosis, celiac disease, surgical removal of part of the stomach or intestines, and some forms of liver disease.
People Who Are Obese
Individuals with a body mass index (BMI) =30 typically have a low plasma concentration of 25(OH)D; this level decreases as obesity and body fat increase. Obesity does not affect skinís capacity to synthesize vitamin D, but greater amounts of subcutaneous fat sequester more of the vitamin and alter its release into the circulation. Even with orally administered vitamin D, BMI is inversely correlated with peak serum concentrations, probably because some vitamin D is sequestered in the larger pools of body fat.
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Vitamin D Disease and Deficiency
Nutrient deficiencies are usually the result of dietary inadequacy, impaired absorption and use, increased requirement, or increased excretion.
A vitamin D deficiency can occur when usual intake is lower than recommended levels over time, exposure to sunlight is limited, the kidneys cannot convert vitamin D to its active form, or absorption of vitamin D from the digestive tract is inadequate.
Vitamin D Information
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement.
It is also produced by your body when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two chemical processes in the body for activation.
The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25- dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol.
Vitamin D is essential for promoting calcium absorption in the gut and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany.
It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts. Without sufficient vitamin D, bones can become thin, brittle, or misshapen.
Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Vitamin D has other roles in human health, including modulation of neuromuscular and immune function and reduction of inflammation.
Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D.
Sources of Vitamin D In Food
Very few foods in nature contain vitamin D. The flesh of fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Small amounts of vitamin D are found in beef liver, cheese, and egg yolks.
Vitamin D in these foods is primarily in the form of vitamin D3 (cholecalciferol) and its metabolite 25(OH)D3. Some mushrooms provide vitamin D2 (ergocalciferol) in variable amounts.
Fortified foods provide most of the vitamin D in the American diet. For example, almost all of the U.S. milk supply is fortified with 100 IU/cup of vitamin D (25% of the Daily Value or 50% of the AI level for ages 14-50 years). In the 1930s, a milk fortification program was implemented in the United States to combat rickets, then a major public health problem. This program virtually eliminated the disorder at that time.
Other dairy products made from milk, such as cheese and ice cream, are generally not fortified. Ready-to-eat breakfast cereals often contain added vitamin D, as do some brands of orange juice, yogurt, and margarine. In the United States, foods allowed to be fortified with vitamin D include cereal flours and related products, milk and products made from milk, and calcium-fortified fruit juices and drinks. Maximum levels of added vitamin D are specified by law.
Ultraviolet (UV) B radiation with a wavelength of 290-315 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3. In other words, sunlight is a great way to get your Vitamin D.
Unfortunately, there are many factors that regulate how much vitamin D you will be able to produce naturally. Season, geographic latitude, time of day, cloud cover, smog, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D synthesis.
The UV energy above 42 degrees north latitude (a line approximately between the northern border of California and Boston) is insufficient for cutaneous vitamin D synthesis from November through February; in far northern latitudes, this reduced intensity lasts for up to 6 months.
Latitudes below 34 degrees north (a line between Los Angeles and Columbia, South Carolina) allow for cutaneous production of vitamin D throughout the year. However, during the summer months Americanís are staying out of the heat and not getting enough sun.
Complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60%. UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D.
Sunscreens with a sun protection factor of 8 or more appear to block vitamin D-producing UV rays, although in practice people generally do not apply sufficient amounts, cover all sun-exposed skin, or reapply sunscreen regularly. Skin likely synthesizes some vitamin D even when it is protected by sunscreen as typically applied.
The factors that affect UV radiation exposure and research to date on the amount of sun exposure needed to maintain adequate vitamin D levels make it difficult to provide general guidelines.
It has been suggested by some vitamin D researchers, for example, that approximately 5-30 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis and that the moderate use of commercial tanning beds that emit 2-6% UVB radiation is also effective. Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement.
2 Forms Of Vitamin D In Dietary supplements
In supplements and fortified foods, vitamin D is available in two forms, D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D2 is manufactured by the UV irradiation of ergosterol in yeast, and vitamin D3 is manufactured by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol.
The two forms have traditionally been regarded as equivalent based on their ability to cure rickets, but evidence has been offered that they are metabolized differently.
Vitamin D3 could be more than three times as effective as vitamin D2 in raising serum 25(OH)D concentrations and maintaining those levels for a longer time, and its metabolites have superior affinity for vitamin D-binding proteins in plasma. Many supplements are being reformulated to contain vitamin D3 instead of vitamin D2.