British Journal of Nutrition

Short Communication

Vitamin A status is associated with T-cell responses in Bangladeshi men

Shaikh M. Ahmada1a2, Marjorie J. Haskella1, Rubhana Raqiba2 and Charles B. Stephensena1a3 c1

a1 Department of Nutrition, Program in International and Community Nutrition, University of California, Davis, CA, USA

a2 Immunology Laboratory, Laboratory Sciences Division, International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B), Dhaka, Bangladesh

a3 USDA Western Human Nutrition Research Center, University of California, 430 West Health Sciences Drive, Davis, CA 95616, USA

Abstract

Recommendations for vitamin A intake are based on maintaining liver stores of ≥ 0·070 μmol/g, which is sufficient to maintain normal vision. We propose that higher levels may be required to maintain normal immune function. To test this hypothesis, we conducted an 8-week residential study among thirty-six healthy Bangladeshi men with low vitamin A stores. Subjects were randomised to receive vitamin A (240 mg in four doses) or placebo during study weeks 2 and 3. Vitamin A stores were estimated by isotopic dilution at week 8. Total T-cells, the naive T-cells:memory T-cells ratio and mitogen-induced lymphocyte proliferation were positively and significantly correlated with vitamin A stores (P < 0·05). Mitogen-stimulated IL-2, IL-4 and TNFα increased significantly (P < 0·05) in the vitamin A but not placebo group after supplementation, while IL-10 production was significantly and negatively correlated with vitamin A stores (P < 0·05). Segmented linear regression analysis revealed that naive T-cell counts and T-cell blastogenesis were positively associated with vitamin A stores above but not below 0·070 μmol/g liver. These data show that increasing vitamin A stores above the level that maintains normal vision enhances some measures of T-cell-mediated immunity, suggesting a difference in requirements for maintaining vision and immune function.

(Received December 01 2008)

(Revised February 25 2009)

(Accepted March 03 2009)

(Online publication April 01 2009)

Correspondence:

c1 Corresponding author: Dr Charles B. Stephensen, fax +1 530 752 5295, email cstephen@whnrc.usda.gov

Footnotes

Abbreviations: ICDDR,B, International Centre for Diarrhoeal Disease Research, Bangladesh; IFNγ, interferon γ; PBMC, peripheral blood mononuclear cells; PHA, phytohaemagglutinin; SI, stimulation index; Th1, T helper type 1; Th2, T helper type 2

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