Folate and Vitamin B12 Blood Concentrations Vary by Race and Ethnicity; Supplement Users Have Higher Concentrations

For Release: December 15, 1999

Contact: NCHS Press Office (301) 458-4800

E-mail: paoquery@cdc.gov

Series 11, No. 243. Blood Folate and Vitamin B12: United States, 1988-94. 84 pp. (PHS) 99-1693. GPO stock number and price forthcoming [PDF - 718 KB]

A new report from the National Center for Health Statistics, Centers for Disease Control and Prevention shows the distribution of concentrations of serum and red blood cell folate and presents the first national estimates of serum vitamin B12 for the U.S. population. These measurements of the amount of vitamins in the blood are important because of the link between inadequate folate in pregnant women and neural tube defects in newborns and a potential association of folate, B12 and other B vitamins with the risk for cardiovascular disease and certain cancers. Reference data in this report will be used to establish and evaluate nutrition policies such as the impact of the recently enacted food fortification policies.

Major findings in the report show:

• More than one definition of low serum folate is used to estimate the number of people with inadequate folate. Depending on the definition that is used, the prevalence of low serum folate among all women of child-bearing age ranges from 4 to 22 percent. Therefore, the number of women who may be affected ranges from a low of 3.7 million to as many as 14.3 million women.
• For men and women, there are significant differences by race and ethnicity in blood folate concentrations. Non-Hispanic white people have higher mean serum and red blood cell folate than non-Hispanic black people and Mexican Americans. Thus, inadequate folate may be more prevalent among non-Hispanic black people and Mexican Americans and may be related to diet choices and knowledge of and use of supplements.
• Serum vitamin B12 concentrations are also subject to differences by race and ethnicity. Reversing the pattern seen with folate, non-Hispanic white people have lower concentrations of serum B12 than do non-Hispanic black people and Mexican Americans. Also, median serum vitamin B12 is highest in the youngest age groups and decreases across older age groups.
• Recent use of supplements had a significant effect on blood concentrations of these vitamins. Those who reported using a vitamin and/or mineral supplement in the 24 hours prior to testing had higher concentrations of serum folate and serum vitamin B12.

"Blood Folate and Vitamin B12: United States, 1988-94" presents national estimates of serum and red blood cell folate and serum vitamin B12 distributions for persons 4 years of age and over by sociodemographic variables, including sex, age, race, ethnicity, poverty and education levels.

Data were collected in the third National Health and Nutrition Examination Survey through interviews, physical examination and standardized laboratory tests. Data were collected and analyzed by the National Center for Health Statistics in collaboration with the National Center for Environmental Health and the National Center for Chronic Disease Prevention and Health Promotion, all of the Centers for Disease Control and Prevention. The National Center for Environmental Health analyzed the blood specimens collected in the survey.