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Title: Obesity is associated with increased red blood cell folate despite lower dietary intakes and serum concentrations

Author
item BIRD, JULIA - University Of Massachusetts
item RONNENBERG, ALAYNE - Cha University
item CHOI, SANG-WOON - University Of Massachusetts
item DU, FANGLING - Shandong Academy Of Agricultural Sciences
item MASON, JOEL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item LIU, ZHENHUA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2014
Publication Date: 11/12/2014
Citation: Bird, J.K., Ronnenberg, A.G., Choi, S., Du, F., Mason, J.B., Liu, Z. 2014. Obesity is associated with increased red blood cell folate despite lower dietary intakes and serum concentrations. Journal of Nutrition. 145(1):79-86. https://doi.org/10.3945/jn.114.199117.

Interpretive Summary: Although obesity is prevalent worldwide, few studies have investigated whether obesity interacts with status of the B vitamin, folate. Based on data from the nationally representative NHANES survey, this study examined the association between a measure of obesity (body mass index [BMI],) factors associated with obesity such as elevated blood sugar levels and high blood triglyceride levels, and blood measures of folate status. Nearly 4,000 adults from the NHANES survey were used as the study population. The results demonstrated that folate concentrations in blood serum were lower in obese groups compared to the desirable BMI and overweight categories, which paralleled lower dietary intakes in this group. In contrast, red blood cell (RBC) folate, which is thought to better reflect the amount of the vitamin in bodily tissues, increased incrementally with BMI. An inverse relationship was observed between BMI and serum folate, but a positive relation was observed between BMI and RBC folate. Waist circumference, serum triglycerides, and fasting plasma sugar each displayed significant positive relationships with RBC folate, although relationships with serum folate were not significant or consistent. We conclude that obesity is associated with decreased serum folate levels but positively associated with RBC folate levels. This study does not determine whether there is a cause and effect relationship between adiposity and measures of folate status, but these relationships nevertheless need to be considered when examining the folate status of a population since they raise questions as to what measure of folate status is more accurate in populations containing people with various degrees of adiposity.

Technical Abstract: Although obesity is prevalent worldwide, few studies have investigated whether obesity interacts with status of the B vitamin, folate. Based on data from the nationally representative NHANES survey, this study examined the association between a measure of obesity (body mass index [BMI],) factors associated with obesity such as elevated blood sugar levels and high blood triglyceride levels, and blood measures of folate status. Nearly 4,000 adults from the NHANES survey were used as the study population. The results demonstrated that folate concentrations in blood serum were lower in obese groups compared to the desirable BMI and overweight categories, which paralleled lower dietary intakes in this group. In contrast, red blood cell (RBC) folate, which is thought to better reflect the amount of the vitamin in bodily tissues, increased incrementally with BMI. An inverse relationship was observed between BMI and serum folate, but a positive relation was observed between BMI and RBC folate. Waist circumference, serum triglycerides, and fasting plasma sugar each displayed significant positive relationships with RBC folate, although relationships with serum folate were not significant or consistent. We conclude that obesity is associated with decreased serum folate levels but positively associated with RBC folate levels. This study does not determine whether there is a cause and effect relationship between adiposity and measures of folate status, but these relationships nevertheless need to be considered when examining the folate status of a population since they raise questions as to what measure of folate status is more accurate in populations containing people with various degrees of adiposity.