Anemia
Anemia occurs when the body has a low number of red blood cells (RBCs). These cells carry oxygen throughout the body. Fewer RBCs limit the body’s oxygen level.
Risk factors
Risk factors for anemia include:
- Low dietary iron and folate (vitamin B) intake
- Serious illnesses including internal bleeding, kidney disease, cancer, diabetes, HIV/AIDS, and liver disease
- Low vitamin D levels
Sunlight exposure and risk
Dr. John Cannell of the Vitamin D Council presented data on oxygen-carrying capacity of athletes from the mid-1950s. The data showed that the blood’s ability to carry oxygen peaks in late summer, suggesting that UVB during the summer increased RBC count.
Vitamin D and anemia
Vitamin D levels
There are a number of studies linking lower vitamin D levels and higher anemia risk:
- In an Australian study of people with noncholestatic chronic liver disease, lower vitamin D levels were associated with anemia.
- Pregnant women in Tanzania with low vitamin D levels were compared to those with adequate vitamin D levels. The women with low levels had a much higher risk of anemia.
- In the United States, 41% of patients with chronic kidney disease had anemia. Lower vitamin D levels were associated with lower hemoglobin levels and anemia.
- A study in Los Angeles found a link between vitamin D deficiency and anemia.
- A U.S. study compared people with and without anemia. Those with anemia were more likely to have low vitamin D levels.
- Another study reported a direct connection between vitamin D levels and maximum oxygen consumption.
How vitamin D works
It is not known how vitamin D affects red blood cells.
Prevention
There are no reported studies of vitamin D preventing anemia. However, based on results for other diseases, vitamin D levels above 30–40 ng/mL (75–100 nmol/L) may increase RBCs and oxygen in the blood.
Treatment
According to studies, RBCs rebuild more quickly in people who have higher vitamin D levels. These studies also used iron and other agents to stimulate RBCs. Anyone with anemia should seek medical care.
Acknowledgements
This evidence summary on anemia was written by: William B. Grant, Ph.D. Sunlight, Nutrition, and Health Research Center (SUNARC) P.O. Box 641603 San Francisco, CA 94164-1603, USA www.sunarc.org wbgrant@infionline.net
Complete bibliography of research used in this summary
The research we have cited in our summary is listed below, with links to PubMed abstracts and full-text for those who wish to explore further.
References
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