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Amazing Vitamin D |
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Vitamin D, while classified as a vitamin, is actually a hormone. It is required throughout life and can greatly benefit the formation of bone. Its presence allows our bodies to absorb calcium, which we know strengthens our bones. Adequate vitamin D helps protect us from rickets, osteomalacia and osteoporosis, conditions where bones are weak and more likely to break. Vitamin D and may well have other positive benefits to the immune system and can help suppress degenerative diseases, hypertension and certain cancers.
Unfortunately, it is nearly absent in our natural food supply. One study suggested that at least 30% of the population is deficient, and this deficiency has been shown to contribute to heart disease, cancer, chronic pain, and depression. To reduce the risk of these diseases many doctors and researchers are recommending intakes of vitamin D that are higher than the current government dietary recommendations.
What are good sources of vitamin D?
- Sun Exposure--vitamin D comes almost exclusively from sun exposure. The skin absorbs Ultraviolet (UV) B radiation and converts it to vitamin D3. UVB does not penetrate glass or windows. With changes in season, geographic latitude, time of day, pollution, and use of sunscreen, UVB exposure may also be limited. While this is still a great way to get vitamin D, there are valid health concerns that cause many people to limit their exposure to UV rays.
- Food-flesh of fish (salmon, mackerel, tuna) and fish liver oils are the best sources. Smaller amounts of vitamin D are found in egg yolks, beef liver, and cheese.
- Fortified Foods-provide most of the vitamin D in the American diet. Milk began fortification in the 1930's, which virtually eliminated rickets at the time. Also look for fortified cereals, some brands of orange juice, yogurt and margarine. Cheese and ice cream are generally not fortified.
Who is at most risk for vitamin D deficiency?
- Breastfed infants-vitamin D requirements can't be met by human milk alone.
- Adults over 50-skin synthesizes less vitamin D.
- Limited Sun Exposure-those who are restricted to indoor environments, wear long robes or head coverings, live in northern climates.
- Dark Skin-the pigment melanin in darker skin reduces the skin's ability to produce vitamin D from exposure to sun.
- Fat Malabsorption-can be associated with a variety of medical conditions and some gastric bypass surgeries.
- Obese-greater amounts of subcutaneous fat restrict vitamin D's release into the circulation.
How much vitamin D is necessary for adults?
This is a topic that has been under great debate lately. The current governmental guidelines recommend:
- Adults up to 50 years--------- 200 IU (International Units)
- Adults 50-70 years------------ 400 IU
- Adults older than 70--------- 600 IU * An upper limit of 2000 IU for safety has been set by the government, as vitamin D toxicity is possible.
** New research is showing that these levels may not be appropriate and that anywhere from 1000-1700 IU of vitamin D may be necessary to prevent a deficiency.
The best way to know if you need more vitamin D is to have your healthcare provider check your D3 levels. If you need to increase your uptake, eat more of the foods listed above, talk to your physician about a supplement or try to get about 15 minutes of sun exposure twice a week.
Information for this article has been taken from the NIH factsheets on vitamin D. For more information, check out the National Institute of Health.
Article written May 2009
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