Vitamin D Replacement Dosage

As of date of publication, the vitamin D replacement dosage is a topic of debate between physicians, researchers and the government. The correct supplementation recommendation has come under fire as these individuals are not able to agree on the suggested blood serum level and the amount of vitamin D necessary to maintain that level. While the Institute of Medicine's Food and Nutrition Board raised the recommended vitamin D levels in 2010, many health care providers do not believe these levels were raised high enough. Vitamin D is an essential fat-soluble vitamin necessary for the absorption of calcium. According to "Scientific American," three-quarters of adolescents and adults in the United States are considered deficient in vitamin D.

Function

Vitamin D is a nutrient necessary for healthy, strong bones. It maintains bones by aiding the body in calcium absorption from food and supplements. A lack of vitamin D can cause you to develop soft, thin and brittle bones. This condition is known as rickets in children and osteomalacia in adults. Vitamin D is needed by the muscles for movement, the nerves to send messages from the brain throughout the body and the immune system to fight off invading microorganisms. Adequate vitamin D levels are thought to protect against osteoporosis, hypertension, cancer and autoimmune disorders.

Sources

There are two forms of vitamin D important to humans: vitamin D-2, or ergocalciferol, and vitamin D-3, or cholecalciferol. Vitamin D-2 is synthesized by plants while vitamin D-3 is synthesized by the skin when exposed to ultraviolet rays from sunlight. Vitamin D is naturally present in very few foods. Fortified foods provide the majority of vitamin D in your diet and can be made with either vitamin D-2 or D-3. Vitamin D-rich foods include cod liver oil; fish such as tuna, salmon and mackerel; beef liver, egg yolks and cheese and mushrooms. Foods fortified with vitamin D include milk, breakfast cereals, orange juice, yogurt, margarine and certain soy beverages. Vitamin D, sometimes called the "sunshine vitamin," is also absorbed through the skin after exposure to sunlight. Sun exposure is a significant source for most people; as little as 10 minutes in the sun can prevent deficiencies. However, depending upon where you live, your access to sunlight may be limited.

Deficiency

According to "Scientific American," there has been a dramatic increase in vitamin D deficiency in the United States. This trend is illustrated in research that measured vitamin D levels between 1988 and 1994 when 45 percent of those examined in the federal government's National Health and Nutrition Examination Survey had a sufficient amount of vitamin D in their blood compared to just 23 percent surveyed a decade later. Most Americans have a vitamin D level lower than 75 nmol/L while normal vitamin D levels are greater than or equal to 50 nmol/L. Vitamin D deficiency is defined as having levels below 30 nmol/L. Vitamin D deficiencies result in soft, porous and bendable bones, muscle weakness and pain.

Recommended Replacement Dosage

The Institute of Medicine announced new dietary reference intakes for vitamin D in late 2010. According to Dr. Joel Fuhrman, it is the consensus of the medical community that the previous 400 IU per day of vitamin D was insufficient. The Institute of Medicine increased the recommended intake level of vitamin D to 600 IU per day for all people under the age of 70 and raised the tolerable upper limit to 4,000 IU from 2,000 IU daily. Additionally, the new definition of vitamin D deficiency is a level equal to or less than 20 nmol/l. However, physicians and researchers believe that supplementation of at least 1,000 IU of vitamin D is necessary for most individuals to meet replacement vitamin D levels.

Controversy

Part of the controversy surrounding the recent change in vitamin D replacement levels concerns the association between low vitamin D status and conditions such as cardiovascular disease, certain cancers, cognitive decline, diabetes, depression, pregnancy complications and autoimmune diseases. Due to a lack of sufficient evidence from controlled trials to conclusively confirm the benefits of vitamin D supplementation outside of overall bone health, the Institute of Medicine did not see fit to raise the daily recommendations any higher than 600 IU of vitamin D per day. Physicians indicate that the increase in the tolerable upper limit is a step in the right direction. Conversely, lowering the vitamin D deficiency level is a potentially dangerous move for certain individuals. As discussed by the Harvard School of Public Health, a complicating factor in determining the appropriate daily amount of vitamin D needed is the exposure to sunlight and the vitamin D produced by the skin which is rapidly absorbed into the blood. While a vitamin D intake of 800 IU per day may be too low for a person with minimal sun exposure, it may be sufficient for someone who receives ample sun exposure.