Vitamin D: One Size Doesn't Fit All
This study suggests current optimal or "normal" vitamin D levels may not be applicable to African Americans
Getting adequate vitamin D from a combination of sun exposure and diet plays a role in keeping bones and muscles strong, lessening risk of heart disease and diabetes, and warding off cancer, allergies, and asthma. Many people get their vitamin D blood levels tested, and take supplements if levels are low, though health experts are now questioning whether everyone with "low" vitamin D levels truly is deficient.
Dialing in on "D"eficiency
To better understand normal and deficient vitamin D levels, researchers studied the relationship between a hormone (parathyroid) and vitamin D in African American and white 50-to-79-year-old adults. Parathyroid hormone is produced in the body to help regulate calcium balance, and as vitamin D levels go up, parathyroid hormone levels go down.
The bottom of the normal vitamin D range is considered the level above which parathyroid hormone levels cannot be lowered any further. Current guidelines set this number at 30 ng per ml, meaning a person would not be considered low in vitamin D until his or her blood level dropped below 30 ng per ml.
The study suggests the "normal" vitamin D level may be different for African Americans and whites.
In other words, adequate vitamin D blood levels may begin around 20 ng per ml for African Americans, and around 30 ng per ml for whites.
What's normal for you?
This study suggests current optimal or "normal" vitamin D levels in whites may not be applicable to African Americans, or black people from any location. This is important: for African Americans, one study even suggests harm with higher vitamin D levels. Among 340 African Americans with type 2 diabetes, those with the highest D levels were more likely to have plaque build up in their arteries, a risk factor for heart attack and stroke. That study's author, Dr. Barry Freedman pointed out, "We need to determine whether we should be targeting the same vitamin D level in blacks as whites, and better understand the cardiovascular effects of supplementing vitamin D in African-Americans."
In the meantime
Here are some tips to guide your vitamin "D"ecisions:
(Osteoporos Int 2012; 23:2283-91; J Clin Endocrinol Metab 2010; 95:76-83)
Suzanne Dixon, MPH, MS, RD, an author, speaker, and internationally recognized expert in chronic disease prevention, epidemiology, and nutrition, has taught medical, nursing, public health, and alternative medicine coursework. She has delivered over 150 invited lectures to health professionals and consumers and is the creator of a nutrition website acclaimed by the New York Times and Time magazine. Suzanne received her training in epidemiology and nutrition at the University of Michigan, School of Public Health at Ann Arbor.