Dissertation/Thesis Abstract

Foods and Nutrients Associated with Vitamin B12 Biomarkers among Vegetarian and Non-Vegetarian Participants of the Adventist Health Study-2 Calibration Study
by Damayanti, Didit, Dr.P.H., Loma Linda University, 2014, 148; 3721154
Abstract (Summary)

In the United States, the prevalence of vitamin B12 deficiency is 3-26%, depending on the diagnostic criteria used. Although the value placed on vitamin B12 concentrations in the blood has focused on the vitamin's role in preventing anemia, the prevention of low and marginal vitamin B12 status also is important because these conditions can lead to serious neurologic and neuropsychiatric abnormalities in adults and the elderly, even without associated anemia. Besides malabsorption, adherence to a vegetarian diet may contribute to inadequate vitamin B12 intake.

The objectives of this study were to examine: 1) the association between dietary factors (B12 from supplements, fortified foods, and foods from animal sources) and biomarkers of vitamin B12 status (holotranscobalamin or holoTC and serum vitamin B12 concentrations) among vegetarian and non-vegetarian participants of the Adventist Health Study-2 (AHS-2) Calibration Study after adjusting for confounding variables; and 2) to identify which nutrients and demographic characteristics are associated with homocysteine concentration after adjusting for confounding factors.

A cross-sectional analysis was conducted using secondary data from the calibration study (n=1,011) of the Adventist Health Study 2. Descriptive statistics, correlations, and multiple linear regressions were used for analyses. Study participants had a median age of 58 years (age range 29 to 94 years), approximately 50% were white, and 66% were females.

Study results showed that supplements containing vitamin B12 were positively associated (p<0.001) with plasma vitamin B12 concentrations, particularly in the upper tertile. Vitamin B12 from fortified foods and milk substitutes was positively associated with plasma B12 concentrations in all subjects, and B12 from milk substitutes was positively associated with holoTC in non-vegetarians but not in lacto-ovo vegetarians. Among those who did not use B12 supplements, B12 from fortified foods was positively associated (p=0.004) with holoTC and serum B12 (p=0.033), while B12 from milk substitutes was positively associated (p=0.001) with holoTC and serum B12 (p=0.007).

Age (p <0.001 for all subjects) and gender (p<0.001) were significant demographic characteristics associated with homocysteine concentrations within this population. Total folate intake from diet and supplements (p<0.001) were strongly inversely associated with homocysteine independent of confounding factors, followed by total vitamin B12 (p=0.001), and B6 intake (p<0.001) among all subjects. Intake of vitamin B12 was significantly inversely associated with homocysteine in non-vegetarians, but serum vitamin B12 and holoTC were significantly inversely associated with homocysteine in all subjects.

In conclusion, B12 from supplements, fortified foods, and milk substitutes may improve the vitamin B12 status of the population. Besides age and gender, intake of total folate, and vitamins B12 and B6 were inversely associated with homocysteine levels.

Indexing (document details)
Advisor: Haddad, Ella
Commitee: Beeson, William Lawrence, Jaceldo-Siegl, Karen
School: Loma Linda University
Department: Nutrition
School Location: United States -- California
Source: DAI-B 77/01(E), Dissertation Abstracts International
Subjects: Nutrition
Keywords: Dietary intake, Holotranscobalamin, Homocysteine, Serum B12, Vegetarians, Vitamin B12
Publication Number: 3721154
ISBN: 978-1-339-02486-8
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