High habitual dietary alpha-linolenic acid intake is associated with decreased plasma soluble interleukin-6 receptor concentrations in male twins.
BACKGROUND
alpha-Linolenic acid (ALA) is associated with a low risk of cardiovascular disease; however, the underlying mechanism is not completely known.


OBJECTIVE
The objective was to examine whether habitual dietary ALA intake is associated with plasma concentrations of inflammatory biomarkers after control for shared genetic and common environmental factors.


METHODS
We cross-sectionally studied 353 middle-aged male twins. Habitual diet was assessed with the Willett food-frequency questionnaire. Fasting plasma concentrations of interleukin-6 (IL-6) and its soluble receptor (sIL-6R), high-sensitivity C-reactive protein (hsCRP), and tumor necrosis factor-alpha (TNF-alpha) were measured. Linear mixed-effect regression analysis was used to partition the overall association into within- and between-pair associations.


RESULTS
A 1-g increment in habitual dietary ALA intake was associated with 11.0% lower concentrations of sIL-6R (P = 0.004) but not of IL-6 (P = 0.31), TNF-alpha (P = 0.16), or hsCRP (P = 0.36) after adjustment for energy intake, nutritional factors, known cardiovascular disease risk factors, and medications. After further control for shared genetic and common environmental factors by comparison of brothers within a twin pair, a twin with a 1-g higher ALA intake was likely to have 10.9% (95% CI: 3.7%, 17.6%; P = 0.004) lower sIL-6R concentrations than his co-twin with a low intake, whereas ALA intake was not significantly associated with plasma concentrations of IL-6, TNF-alpha, or hsCRP. These results were validated by using 1000 bootstrap samples.


CONCLUSIONS
Habitual dietary ALA intake is inversely associated with plasma sIL-6R concentrations independent of shared genetic and common environmental influences. Lowering sIL-6R may be a mechanism underlying the cardioprotective properties of habitual dietary ALA. This study was registered at clinicaltrials.gov as NCT00017836.
Dai
Jun
J
Department of Applied Health Science, Indiana University, Bloomington, IN, USA. jdai@indiana.edu
Ziegler
Thomas R
TR
Bostick
Roberd M
RM
Manatunga
Amita K
AK
Jones
Dean P
DP
Goldberg
Jack
J
Miller
Andrew
A
Vogt
Gerald
G
Wilson
Peter W
PW
Jones
Linda
L
Shallenberger
Lucy
L
Vaccarino
Viola
V
D002097:C-Reactive Protein / Q000187:drug effects / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000523:psychology; D003863:Depression / Q000453:epidemiology; D004032:Diet; D019587:Dietary Supplements; D002149:Energy Intake; D005227:Fatty Acids / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008019:Life Style; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D019947:Receptors, Interleukin-6 / Q000097:blood* / Q000187:drug effects; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000187:drug effects; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D049629:Waist-Hip Ratio; D017962:alpha-Linolenic Acid / Q000494:pharmacology*
D005227:Fatty Acids; D015850:Interleukin-6; D008055:Lipids; D019947:Receptors, Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D017962:alpha-Linolenic Acid; D002097:C-Reactive Protein
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