Energy restriction with different protein quantities and source: implications for innate immunity.
OBJECTIVE
Physical age, energy restriction (ER), and weight loss have been reported to suppress indices of innate immunity, which may increase the risk of illness. To evaluate these interactions, we recruited older, postmenopausal women (50 to 80 years) to fill one of the following 9-week ER (1250 kcal/d) groups: beef [n = 14; reported intakes 46% carbohydrate (CHO):24% protein (PRO):30% fat], chicken (n = 15; 51% CHO:25% PRO:24% fat), or CHO (n = 14; 59% CHO:17% PRO:24% fat), or a non-intervention control (n = 11).


METHODS
Fasting blood was collected before and after ER to determine leukocyte phenotype, neutrophil oxidative burst capacity, natural killer cell activity, stimulated interleukin-2 and interferon-gamma production, and blood zinc and iron concentrations.


RESULTS
No significant effects of ER (8.6% weight loss) or PRO quantity and source were found for the majority of indices of innate immunity. Small but significant (p < 0.05) declines in interleukin-2 production were found in the chicken and CHO groups only; however, the clinical significance of this finding is not known.


CONCLUSIONS
In the present study, 9 weeks of moderate ER did not suppress immunity in postmenopausal women. Also, contrary to our hypothesis, differential zinc and iron intakes did not significantly alter immunity.
McFarlin
Brian K
BK
Department of Health and Human Performance, University of Houston, 104U Garrison, Houston, TX 77204-6015, USA. bmcfarlin@uh.edu
Flynn
Michael G
MG
Mahon
Anne K
AK
Stewart
Laura K
LK
Timmerman
Kyle L
KL
Lyle
Roseann M
RM
Campbell
Wayne W
WW
D000368:Aged; D000369:Aged, 80 and over; D004038:Diet, Reducing; D004044:Dietary Proteins / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004306:Dose-Response Relationship, Immunologic; D002149:Energy Intake / Q000276:immunology / Q000502:physiology*; D005260:Female; D006801:Humans; D007113:Immunity, Innate; D019266:Iron, Dietary / Q000008:administration & dosage / Q000276:immunology; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy / Q000276:immunology*; D017698:Postmenopause; D015431:Weight Loss; D015032:Zinc / Q000008:administration & dosage / Q000276:immunology
D004044:Dietary Proteins; D019266:Iron, Dietary; D015032:Zinc